Internet Engineering Task Force W. Wang
Internet-Draft Zhejiang Gongshang University
Intended status: Standards Track E. Haleplidis
Expires: August 1, 2013 University of Patras
K. Ogawa
NTT Corporation
C. Li
Hangzhou H3C Tech. Co., Ltd.
J. Halpern
Ericsson
January 28, 2013
ForCES Logical Function Block (LFB) Library
draft-ietf-forces-lfb-lib-10
Abstract
This document defines basic classes of Logical Function Blocks (LFBs)
used in the Forwarding and Control Element Separation (ForCES). The
basic LFB classes are defined according to ForCES FE model and ForCES
protocol specifications, and are scoped to meet requirements of
typical router functions and considered as the basic LFB library for
ForCES. The library includes the descriptions of the LFBs and the
XML definitions.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 1, 2013.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Table of Contents
1. Terminology and Conventions . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Scope of the Library . . . . . . . . . . . . . . . . . . 8
3.2. Overview of LFB Classes in the Library . . . . . . . . . 10
3.2.1. LFB Design Choices . . . . . . . . . . . . . . . . . 10
3.2.2. LFB Class Groupings . . . . . . . . . . . . . . . . . 11
3.2.3. Sample LFB Class Application . . . . . . . . . . . . 12
3.3. Document Structure . . . . . . . . . . . . . . . . . . . 13
4. Base Types . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.1. Data Types . . . . . . . . . . . . . . . . . . . . . . . 14
4.1.1. Atomic . . . . . . . . . . . . . . . . . . . . . . . 14
4.1.2. Compound Struct . . . . . . . . . . . . . . . . . . . 15
4.1.3. Compound Array . . . . . . . . . . . . . . . . . . . 15
4.2. Frame Types . . . . . . . . . . . . . . . . . . . . . . . 16
4.3. MetaData Types . . . . . . . . . . . . . . . . . . . . . 16
4.4. XML for Base Type Library . . . . . . . . . . . . . . . . 17
5. LFB Class Description . . . . . . . . . . . . . . . . . . . . 43
5.1. Ethernet Processing LFBs . . . . . . . . . . . . . . . . 43
5.1.1. EtherPHYCop . . . . . . . . . . . . . . . . . . . . . 44
5.1.2. EtherMACIn . . . . . . . . . . . . . . . . . . . . . 46
5.1.3. EtherClassifier . . . . . . . . . . . . . . . . . . . 48
5.1.4. EtherEncap . . . . . . . . . . . . . . . . . . . . . 50
5.1.5. EtherMACOut . . . . . . . . . . . . . . . . . . . . . 52
5.2. IP Packet Validation LFBs . . . . . . . . . . . . . . . . 53
5.2.1. IPv4Validator . . . . . . . . . . . . . . . . . . . . 53
5.2.2. IPv6Validator . . . . . . . . . . . . . . . . . . . . 55
5.3. IP Forwarding LFBs . . . . . . . . . . . . . . . . . . . 57
5.3.1. IPv4UcastLPM . . . . . . . . . . . . . . . . . . . . 57
5.3.2. IPv4NextHop . . . . . . . . . . . . . . . . . . . . . 59
5.3.3. IPv6UcastLPM . . . . . . . . . . . . . . . . . . . . 61
5.3.4. IPv6NextHop . . . . . . . . . . . . . . . . . . . . . 63
5.4. Redirect LFBs . . . . . . . . . . . . . . . . . . . . . . 65
5.4.1. RedirectIn . . . . . . . . . . . . . . . . . . . . . 65
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5.4.2. RedirectOut . . . . . . . . . . . . . . . . . . . . . 66
5.5. General Purpose LFBs . . . . . . . . . . . . . . . . . . 67
5.5.1. BasicMetadataDispatch . . . . . . . . . . . . . . . . 67
5.5.2. GenericScheduler . . . . . . . . . . . . . . . . . . 69
6. XML for LFB Library . . . . . . . . . . . . . . . . . . . . . 71
7. LFB Class Use Cases . . . . . . . . . . . . . . . . . . . . . 100
7.1. IPv4 Forwarding . . . . . . . . . . . . . . . . . . . . . 100
7.2. ARP processing . . . . . . . . . . . . . . . . . . . . . 102
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 105
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 106
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 107
10.1. LFB Class Names and LFB Class Identifiers . . . . . . . . 107
10.2. Metadata ID . . . . . . . . . . . . . . . . . . . . . . . 109
10.3. Exception ID . . . . . . . . . . . . . . . . . . . . . . 109
10.4. Validate Error ID . . . . . . . . . . . . . . . . . . . . 110
11. Security Considerations . . . . . . . . . . . . . . . . . . . 112
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 113
12.1. Normative References . . . . . . . . . . . . . . . . . . 113
12.2. Informative References . . . . . . . . . . . . . . . . . 113
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 114
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1. Terminology and Conventions
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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2. Definitions
This document follows the terminology defined by the ForCES protocol
in [RFC5810] and by the ForCES FE model in [RFC5812]. The
definitions below are repeated for clarity.
Control Element (CE) - A logical entity that implements the ForCES
protocol and uses it to instruct one or more FEs on how to process
packets. CEs handle functionality such as the execution of
control and signaling protocols.
Forwarding Element (FE) - A logical entity that implements the
ForCES protocol. FEs use the underlying hardware to provide per-
packet processing and handling as directed/controlled by one or
more CEs via the ForCES protocol.
ForCES Network Element (NE) - An entity composed of one or more
CEs and one or more FEs. To entities outside an NE, the NE
represents a single point of management. Similarly, an NE usually
hides its internal organization from external entities.
LFB (Logical Function Block) - The basic building block that is
operated on by the ForCES protocol. The LFB is a well defined,
logically separable functional block that resides in an FE and is
controlled by the CE via ForCES protocol. The LFB may reside at
the FE's datapath and process packets or may be purely an FE
control or configuration entity that is operated on by the CE.
Note that the LFB is a functionally accurate abstraction of the
FE's processing capabilities, but not a hardware-accurate
representation of the FE implementation.
FE Model - The FE model is designed to model the logical
processing functions of an FE, which is defined by the ForCES FE
model document [RFC5812]. The FE model proposed in this document
includes three components; the LFB modeling of individual Logical
Functional Block (LFB model), the logical interconnection between
LFBs (LFB topology), and the FE-level attributes, including FE
capabilities. The FE model provides the basis to define the
information elements exchanged between the CE and the FE in the
ForCES protocol [RFC5810].
FE Topology - A representation of how the multiple FEs within a
single NE are interconnected. Sometimes this is called inter-FE
topology, to be distinguished from intra-FE topology (i.e., LFB
topology).
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LFB Class and LFB Instance - LFBs are categorized by LFB Classes.
An LFB Instance represents an LFB Class (or Type) existence.
There may be multiple instances of the same LFB Class (or Type) in
an FE. An LFB Class is represented by an LFB Class ID, and an LFB
Instance is represented by an LFB Instance ID. As a result, an
LFB Class ID associated with an LFB Instance ID uniquely specifies
an LFB existence.
LFB Metadata - Metadata is used to communicate per-packet state
from one LFB to another, but is not sent across the network. The
FE model defines how such metadata is identified, produced and
consumed by the LFBs. It defines the functionality but not how
metadata is encoded within an implementation.
LFB Component - Operational parameters of the LFBs that must be
visible to the CEs are conceptualized in the FE model as the LFB
components. The LFB components include, for example, flags,
single parameter arguments, complex arguments, and tables that the
CE can read and/or write via the ForCES protocol (see below).
LFB Topology - Representation of how the LFB instances are
logically interconnected and placed along the datapath within one
FE. Sometimes it is also called intra-FE topology, to be
distinguished from inter-FE topology.
Data Path - A conceptual path taken by packets within the
forwarding plane inside an FE. Note that more than one data path
can exist within an FE.
ForCES Protocol - While there may be multiple protocols used
within the overall ForCES architecture, the term "ForCES protocol"
and "protocol" refer to the Fp reference points in the ForCES
Framework in [RFC3746]. This protocol does not apply to CE-to-CE
communication, FE-to-FE communication, or to communication between
FE and CE managers. Basically, the ForCES protocol works in a
master-slave mode in which FEs are slaves and CEs are masters.
This document defines the specifications for this ForCES protocol.
LFB Port - A port refers to an LFB input port or output port. See
Section 3.2 of [RFC5812] for more detailed definitions.
Physical Port - A port refers to a physical media input port or
output port of an FE. A physical port is usually assigned with a
physical port ID, abbreviated with a PHYPortID. This document
mainly deals with physical ports with Ethernet media.
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Logical Port - A conceptually virtual port at data link layer (L2)
or network layer (L3). A logical port is usually assigned with a
logical port ID, abbreviated with a LogicalPortID. The logical
ports can be further categorized with a L2 logical port or a L3
logical port. An L2 logical port can be assigned with a L2
logical port ID, abbreviated with a L2PortID. An L3 logical port
can be assigned with a L3 logical port ID, abbreviated with a
L3PortID. MAC layer VLAN ports belongs to L2 logical ports as
well as logical ports.
LFB Class Library - The LFB class library is a set of LFB classes
that has been identified as the most common functions found in
most FEs and hence should be defined first by the ForCES Working
Group. The LFB Class Library is defined by this document.
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3. Introduction
[RFC5810] specifies Forwarding and Control Element Separation
(ForCES) framework. In the framework, Control Elements (CEs)
configure and manage one or more separate Forwarding Elements (FEs)
within a Network Element (NE) by use of a ForCES protocol. [RFC5810]
specifies the ForCES protocol. [RFC5812] specifies the Forwarding
Element (FE) model. In the model, resources in FEs are described by
classes of Logical Function Blocks (LFBs). The FE model defines the
structure and abstract semantics of LFBs, and provides XML schema for
the definitions of LFBs.
This document conforms to the specifications of the FE model
[RFC5812] and specifies detailed definitions of classes of LFBs,
including detailed XML definitions of LFBs. These LFBs form a base
LFB library for ForCES. LFBs in the base library are expected to be
combined to form an LFB topology for a typical router to implement IP
forwarding. It should be emphasized that an LFB is an abstraction of
functions rather than its implementation details. The purpose of the
LFB definitions is to represent functions so as to provide
interoperability between separate CEs and FEs.
More LFB classes with more functions may be developed in future time
and documented by IETF. Vendors may also develop proprietary LFB
classes as described in the FE model [RFC5812].
3.1. Scope of the Library
It is intended that the LFB classes described in this document are
designed to provide the functions of a typical router. [RFC1812]
specifies that a typical router is expected to provide functions to:
(1) Interface to packet networks and implement the functions
required by that network. These functions typically include:
* Encapsulating and decapsulating the IP datagrams with the
connected network framing (e.g., an Ethernet header and
checksum),
* Sending and receiving IP datagrams up to the maximum size
supported by that network, this size is the network's Maximum
Transmission Unit or MTU,
* Translating the IP destination address into an appropriate
network-level address for the connected network (e.g., an
Ethernet hardware address), if needed, and
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* Responding to network flow control and error indications, if
any.
(2) Conform to specific Internet protocols including the Internet
Protocol (IPv4 and/or IPv6), Internet Control Message Protocol
(ICMP), and others as necessary.
(3) Receive and forward Internet datagrams. Important issues in
this process are buffer management, congestion control, and
fairness.
* Recognizes error conditions and generates ICMP error and
information messages as required.
* Drops datagrams whose time-to-live fields have reached zero.
* Fragments datagrams when necessary to fit into the MTU of the
next network.
(4) Choose a next hop destination for each IP datagram, based on the
information in its routing database.
(5) Usually support an interior gateway protocol (IGP) to carry out
distributed routing and reachability algorithms with the other
routers in the same autonomous system. In addition, some
routers will need to support an exterior gateway protocol (EGP)
to exchange topological information with other autonomous
systems. For all routers, it is essential to provide ability to
manage static routing items.
(6) Provide network management and system support facilities,
including loading, debugging, status reporting, statistcs query,
exception reporting and control.
The classical IP router utilizing the ForCES framework constitutes a
CE running some controlling IGP and/or EGP function or static route
setup and FEs implementing using Logical Function Blocks (LFBs)
conforming to the FE model[RFC5812] specifications. The CE, in
conformance to the ForCES protocol[RFC5810] and the FE model
[RFC5812] specifications, instructs the LFBs on the FE how to treat
received/sent packets.
Packets in an IP router are received and transmitted on physical
media typically referred to as "ports". Different physical port
media will have different ways for encapsulating outgoing frames and
decapsulating incoming frames. The different physical media will
also have different attributes that influence its behavior and how
frames get encapsulated or decapsulated. This document will only
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deal with Ethernet physical media. Other future documents may deal
with other type of media. This document will also interchangeably
refer to a port to be an abstraction that constitutes a PHY and a MAC
as described by the LFBs like EtherPHYCop, EtherMACIn, and
EtherMACOut.
IP packets emanating from port LFBs are then processed by a
validation LFB before being further forwarded to the next LFB. After
the validation process the packet is passed to an LFB where IP
forwarding decision is made. In the IP Forwarding LFBs, a Longest
Prefix Match LFB is used to look up the destination information in a
packet and select a next hop index for sending the packet onward. A
next hop LFB uses the next hop index metadata to apply the proper
headers to the IP packets, and direct them to the proper egress.
Note that in the process of IP packets processing, in this document,
we are adhering to the weak-host model [RFC1122] since that is the
most usable model for a packet processing Network Element.
3.2. Overview of LFB Classes in the Library
It is critical to classify functional requirements into various
classes of LFBs and construct a typical but also flexible enough base
LFB library for various IP forwarding equipments.
3.2.1. LFB Design Choices
A few design principles were factored into choosing how the base LFBs
looked like. These are:
o If a function can be designed by either one LFB or two or more
LFBs with the same cost, the choice is to go with two or more LFBs
so as to provide more flexibility for implementers.
o An LFB should take advantage of its independence as much as
possible and have minimal coupling with other LFBs. The coupling
may be from LFB attributes definitions as well as physical
implementations.
o Unless there is a clear difference in functionality, similar
packet processing in the base LFB library should not be
represented simultaneously as two or more LFBs. For instance, it
should not be simultaneously defined with two different LFBs for
the same next hop processing. Or else, it may add extra burden on
implementation to achieve interoperability.
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3.2.2. LFB Class Groupings
The document defines groups of LFBs for typical router function
requirements:
(1) A group of Ethernet processing LFBs are defined to abstract the
packet processing for Ethernet as the port media type. As the
most popular media type with rich processing features, Ethernet
media processing LFBs was a natural choice. Definitions for
processing of other port media type like POS or ATM may be
incorporated in the library in future version of the document or
in a future separate document. The following LFBs are defined
for Ethernet processing:
* EtherPHYCop (Section 5.1.1)
* EtherMACIn (Section 5.1.2)
* EtherClassifier (Section 5.1.3)
* EtherEncap (Section 5.1.4)
* EtherMACOut (Section 5.1.5)
(2) A group of LFBs are defined for IP packet validation process.
The following LFBs are defined for IP validation processing:
* IPv4Validator (Section 5.2.1)
* IPv6Validator (Section 5.2.2)
(3) A group of LFBs are defined to abstract IP forwarding process.
The following LFBs are defined for IP forwarding processing:
* IPv4UcastLPM (Section 5.3.1)
* IPv4NextHop (Section 5.3.2)
* IPv6UcastLPM (Section 5.3.3)
* IPv6NextHop (Section 5.3.4)
(4) A group of LFBs are defined to abstract the process for redirect
operation, i.e., data packet transmission between CE and FEs.
The following LFBs are defined for redirect processing:
* RedirectIn (Section 5.4.1)
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* RedirectOut (Section 5.4.2)
(5) A group of LFBs are defined for abstracting some general purpose
packet processing. These processing processes are usually
general to many processing locations in an FE LFB topology. The
following LFBs are defined for redirect processing:
* BasicMetadataDispatch (Section 5.5.1)
* GenericScheduler (Section 5.5.2)
3.2.3. Sample LFB Class Application
Although Section 7 will present use cases for LFBs defined in this
document, this section shows a simple sample LFB class application in
advance so that readers can get a quick overlook of the LFB classes
with the usage.
Figure 1 shows a simple LFB processing path for Ethernet packets
entered from Ethernet physical ports.
+-----+ +------+
| |EtherPHYIn | | from some LFB(s) which
| |<---------------|Ether |<---------- generate Ethernet
| | |MACOut| packets
| | | LFB |
|Ether| +------+
|PHY | +------+
|Cop | | |
|LFB |EtherPHYOut | Ether| to some LFB(s) which
| |--------------->| MACIn|----------> may classify Ethernet
| | | LFB | packets and do IP layer
| | | | processing
+-----+ +------+
Figure 1: A simple sample LFB use case
In the figure, Ethernet packets from outer networks enter via the
EtherPHYCop LFB(Section 5.1.1), which describes Ethernet copper
interface property(like the link speed) at physical layer. After
physical layer process, Ethernet packets are delivered to EtherMACIn
LFB(Section 5.1.2) to describe its MAC layer processing
functions(like locality check). The packets after EtherMACIn LFB may
require further processing to implement various functions(like IP
layer forwarding),therefore some LFBs may follow the EtherMACIn LFB
in topology to describe followed processing functions.
Meanwhile, packets generated by some LFB(s) may need to be submitted
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to outer physical networks. The process is described in the figure
by an EtherMACOut LFB(Section 5.1.5) at MAC layer and the EtherPHYCop
LFB at physical layer.
3.3. Document Structure
Base type definitions, including data types, packet frame types, and
metadata types are presented in advance for definitions of various
LFB classes. Section 4 (Base Types section) provides a description
on the base types used by this LFB library. To enable extensive use
of these base types by other LFB class definitions, the base type
definitions are provided as a separate library.
Within every group of LFB classes, a set of LFBs are defined for
individual function purposes. Section 5 (LFB Class Descriptions
section) provides text descriptions on the individual LFBs. Note
that for a complete definition of an LFB, a text description as well
as a XML definition is required.
LFB classes are finally defined by XML with specifications and schema
defined in the ForCES FE model[RFC5812]. Section 6 (XML LFB
Definitions section) provides the complete XML definitions of the
base LFB classes library.
Section 7 provides several use cases on how some typical router
functions can be implemented using the base LFB library defined in
this document.
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4. Base Types
The FE model [RFC5812] has specified predefined (built-in) atomic
data-types as below:
char, uchar, int16, uint16, int32, uint32, int64, uint64, string[N],
string, byte[N], boolean, octetstring[N], float16, float32, float64.
Note that, unlike SNMP information model SMI([RFC2578]), the FE model
has not defined specific atomic data type for counting purpose. This
document follows not to define specific counter types. To describe
LFB elements for packet statistics which actually require counters on
packets, an unsigned integer, like an uint32 or an uint64 is adopted.
This document states that any LFB element defined for counter purpose
is specified to monotonically increase until it reaches a maximum
value, when it wraps around and starts increasing again from zero.
This document also states that it is implementation's issue how the
unsigned integer element might be maintained to cope with issues like
counter discontinuities when a counter wraps or is reset by any
reasons. If a CE is expected to understand more meanings of the
counter element than stated above, a private definition on the
element between CE and FE may be required.
Based on the atomic data types and with the use of type definition
elements in the FE model XML schema, new data types, packet frame
types, and metadata types can be defined.
To define a base LFB library for typical router functions, a set of
base data types, frame types, and metadata types should be defined.
This section provides a brief description of the base types and a
full XML definition of them as well.
The base type XML definitions are provided with a separate XML
library file named "BaseTypeLibrary". Users can refer to this
library by the statement:
4.1. Data Types
Data types defined in the base type library are categorized by types
of atomic, compound struct, and compound array.
4.1.1. Atomic
The following data types are defined as atomic data types and put in
the base type library:
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Data Type Name Brief Description
-------------- -----------------
IPv4Addr IPv4 address
IPv6Addr IPv6 address
IEEEMAC IEEE MAC address
LANSpeedType LAN speed by value types
DuplexType Duplex types
PortStatusType The possible types of port status, used for
both administrative and operative status.
VlanIDType The type of VLAN ID
VlanPriorityType The type of VLAN priority
SchdDisciplineType Scheduling discipline type
4.1.2. Compound Struct
The following compound struct types are defined in the base type
library:
Data Type Name Brief Description
-------------- -----------------
EtherDispatchEntryType Entry type for Ethernet dispatch table
VlanInputTableEntryType Entry type for VLAN input table
EncapTableEntryType Entry type for Ethernet encapsulation table
MACInStatsType Statistics type for EtherMACIn LFB
MACOutStatsType Statistics type for EtherMACOut LFB
EtherClassifyStatsType Entry type for statistics table in
EtherClassifier LFB.
IPv4PrefixInfoType Entry type for IPv4 prefix table
IPv6PrefixInfoType Entry type for IPv6 prefix table
IPv4NextHopInfoType Entry type for IPv4 next hop table
IPv6NextHopInfoType Entry type for IPv6 next hop table
IPv4ValidatorStatsType Statistics type in IPv4validator LFB
IPv6ValidatorStatsType Statistics type in IPv6validator LFB
IPv4UcastLPMStatsType Statistics type in IPv4UcastLPM LFB
IPv6UcastLPMStatsType Statistics type in IPv6UcastLPM LFB
QueueStatsType Entry type for queue depth table
MetadataDispatchType Entry type for metadata dispatch table
4.1.3. Compound Array
Compound array types are mostly created based on compound struct
types for LFB table components. The following compound array types
are defined in this base type library:
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Data Type Name Brief Description
-------------- -----------------
EtherClassifyStatsTableType Type for Ethernet classifier statistics
information table.
EtherDispatchTableType Type for Ethernet dispatch table
VlanInputTableType Type for VLAN input table
EncapTableType Type for Ethernet encapsulation table
IPv4PrefixTableType Type for IPv4 prefix table
IPv6PrefixTableType Type for IPv6 prefix table
IPv4NextHopTableType Type for IPv4 next hop table
IPv6NextHopTableType Type for IPv6 next hop table
MetadataDispatchTableType Type for Metadata dispatch table
QueueStatsTableType Type for Queue depth table
4.2. Frame Types
According to FE model [RFC5812], frame types are used in LFB
definitions to define packet frame types both an LFB expects at its
input port and the LFB emits at its output port. The
element in the FE model is used to define a new frame type.
The following frame types are defined in the base type library:
Frame Name Brief Description
-------------- ----------------
EthernetII An Ethernet II frame
ARP An ARP packet frame
IPv4 An IPv4 packet frame
IPv6 An IPv6 packet frame
IPv4Unicast An IPv4 unicast packet frame
IPv4Multicast An IPv4 multicast packet frame
IPv6Unicast An IPv6 unicast packet frame
IPv6Multicast An IPv6 multicast packet frame
Arbitrary Any type of packet frames
4.3. MetaData Types
LFB Metadata is used to communicate per-packet state from one LFB to
another. The element in the FE model is used to define
a new metadata type.
The following metadata types are currently defined in the base type
library.
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Metadata Name Metadata ID Brief Description
------------ ---------- -------------
PHYPortID 1 Metadata indicating a physical port ID
SrcMAC 2 Metadata indicating a source MAC address
DstMAC 3 Metadata indicating a destination MAC
address.
LogicalPortID 4 Metadata of a logical port ID
EtherType 5 Metadata indicating an Ethernet type
VlanID 6 Metadata of a VLAN ID
VlanPriority 7 Metadata of a VLAN priority
NextHopIPv4Addr 8 Metadata representing a next hop IPv4
address.
NextHopIPv6Addr 9 Metadata representing a next hop IPv6
address.
HopSelector 10 Metadata indicating a hop selector
ExceptionID 11 Metadata indicating exception types for
exceptional cases during LFB processing.
ValidateErrorID 12 Metadata indicating error types when a
packet passes validation process.
L3PortID 13 Metadata indicating ID of an L3 logical
port.
RedirectIndex 14 Metadata that CE sends to RedirectIn LFB,
indicating an associated packet a group
output port index of the LFB.
MediaEncapInfoIndex 15 A search key a packet uses to look up a
table in related LFBs to select an
encapsulation media.
4.4. XML for Base Type Library
EthernetAll
Packet with any Ethernet type
EthernetII
Packet with Ethernet II type
ARP
ARP packet
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IPv4
IPv4 packet
IPv6
IPv6 packet
IPv4Unicast
IPv4 unicast packet
IPv4Multicast
IPv4 multicast packet
IPv6Unicast
IPv6 unicast packet
IPv6Multicast
IPv6 multicast packet
Arbitrary
Any type of packet
IPv4Addr
IPv4 address
byte[4]
IPv6Addr
IPv6 address
byte[16]
IEEEMAC
IEEE MAC address
byte[6]
LANSpeedType
LAN speed type
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uint32
LAN_SPEED_NONE
Nothing connected
LAN_SPEED_10M
10M Ethernet
LAN_SPEED_100M
100M Ethernet
LAN_SPEED_1G
1G Ethernet
LAN_SPEED_10G
10G Ethernet
LAN_SPEED_40G
40G Ethernet
LAN_SPEED_100G
100G Ethernet
LAN_SPEED_400G
400G Ethernet
LAN_SPEED_1T
1T Ethernet
LAN_SPEED_OTHER
Other LAN speed type
LAN_SPEED_AUTO
LAN speed by auto negotiation
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DuplexType
Duplex mode type
uint32
Auto
Auto negotiation
HalfDuplex
Half duplex
FullDuplex
Full duplex
PortStatusType
Type for port status, used for both administrative and
operative status.
uchar
Disabled
Port disabled
Up
Port up
Down
Port down
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MACInStatsType
Data type defined for statistics in EtherMACIn LFB.
NumPacketsReceived
Number of packets received
uint64
NumPacketsDropped
Number of packets dropped
uint64
MACOutStatsType
Data type defined for statistics in EtherMACOut LFB.
NumPacketsTransmitted
Number of packets transmitted
uint64
NumPacketsDropped
Number of packets dropped
uint64
EtherDispatchEntryType
Data type defined for entry of Ethernet dispatch
table in EtherClassifier LFB.
LogicalPortID
Logical port ID
uint32
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EtherType
The Ethernet type of the Ethernet packet.
uint16
Reserved
A reserved bit space mainly for purpose of padding
and packing efficiency.
uint16
LFBOutputSelectIndex
Index for a packet to select an instance in the
group output port of EtherClassifier LFB to output.
uint32
EtherDispatchTableType
Data type defined for Ethernet dispatch table in
EtherClassifier LFB. The table is composed of an array
of entries with EtherDispatchEntryType data type.
EtherDispatchEntryType
VlanIDType
Data type for VLAN ID
uint16
VlanPriorityType
Data type for VLAN priority
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uchar
VlanInputTableEntryType
Data type for entry of VLAN input table in EtherClassifier
LFB. Each entry of the table contains an incoming port ID,
a VLAN ID and a logical port ID. Every input packet is
assigned with a new logical port ID according to the
packet incoming port ID and the VLAN ID.
IncomingPortID
The incoming port ID
uint32
VlanID
The VLAN ID
VlanIDType
Reserved
A reserved bit space mainly for purpose of padding
and packing efficiency.
uint16
LogicalPortID
The logical port ID
uint32
VlanInputTableType
Data type for the VLAN input table in EtherClassifier
LFB. The table is composed of an array of entries with
VlanInputTableEntryType.
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VlanInputTableEntryType
EtherClassifyStatsType
Data type for entry of statistics table in EtherClassifier
LFB.
EtherType
The Ethernet type of the Ethernet packet.
uint16
Reserved
A reserved bit space mainly for purpose of padding
and packing efficiency.
uint16
PacketsNum
Packets number
uint64
EtherClassifyStatsTableType
Data type for statistics table in EtherClassifier LFB.
EtherClassifyStatsType
IPv4ValidatorStatsType
Data type for statistics in IPv4validator LFB.
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badHeaderPkts
Number of packets with bad header
uint64
badTotalLengthPkts
Number of packets with bad total length
uint64
badTTLPkts
Number of packets with bad TTL
uint64
badChecksumPkts
Number of packets with bad checksum
uint64
IPv6ValidatorStatsType
Data type for statistics in IPv6validator LFB.
badHeaderPkts
Number of packets with bad header
uint64
badTotalLengthPkts
Number of packets with bad total length.
uint64
badHopLimitPkts
Number of packets with bad hop limit.
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uint64
IPv4PrefixInfoType
Data type for entry of IPv4 longest prefix match
table in IPv4UcastLPM LFB. The destination IPv4 address
of every input packet is used as a search key to look up
the table to find out a next hop selector.
IPv4Address
The destination IPv4 address
IPv4Addr
Prefixlen
The prefix length
uchar
ECMPFlag
The ECMP flag
boolean
False
ECMP false, indicating the route
does not have multiple next hops.
True
ECMP true, indicating the route
has multiple next hops.
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DefaultRouteFlag
Default route flag
boolean
False
Default route false, indicating the
route is not a default route.
True
Default route true, indicating the
route is a default route.
Reserved
A reserved bit space mainly for purpose of padding
and packing efficiency.
uchar
HopSelector
The HopSelector produced by the prefix matching LFB,
which will be output to downstream LFB to find next
hop information.
uint32
IPv4PrefixTableType
Data type for IPv4 longest prefix match table in
IPv4UcastLPM LFB. Entry of the table is
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of IPv4PrefixInfoType data type.
IPv4PrefixInfoType
IPv4UcastLPMStatsType
Data type for statistics in IPv4UcastLPM LFB.
InRcvdPkts
Number of received input packets.
uint64
FwdPkts
Number of forwarded packets.
uint64
NoRoutePkts
Number of packets with no route found.
uint64
IPv6PrefixInfoType
Data type for entry of IPv6 longest prefix match
table in IPv6UcastLPM LFB. The destination IPv6 address
of every input packet is used as a search key to look up
the table to find out a next hop selector.
IPv6Address
The destination IPv6 address
IPv6Addr
Prefixlen
The prefix length
uchar
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ECMPFlag
ECMP flag
boolean
False
ECMP false
True
ECMP true
DefaultRouteFlag
Default route flag
boolean
False
Default false
True
Default route true
Reserved
A reserved bit space mainly for purpose of padding
and packing efficiency.
uchar
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HopSelector
The HopSelector produced by the prefix matching LFB,
which will be output to downstream LFB to find next
hop information.
uint32
IPv6PrefixTableType
Data type for IPv6 longest prefix match table in
IPv6UcastLPM LFB. Entry of the table is
of IPv6PrefixInfoType data type.
IPv6PrefixInfoType
IPv6UcastLPMStatsType
Data type for statistics in IPv6UcastLPM LFB
InRcvdPkts
Number of received input packets
uint64
FwdPkts
Number of forwarded packets
uint64
NoRoutePkts
Number of packets with no route found.
uint64
IPv4NextHopInfoType
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Data type for entry of IPv4 next hop information table
in IPv4NextHop LFB. The table uses a hop selector
received from upstream LFB as a search key to look up
index of the table to find the next hop information.
L3PortID
The ID of the logical output port that is to pass
onto downstream LFB, indicating what port to the
neighbor is as defined by L3.
uint32
MTU
Maximum Transmission Unit for outgoing port
uint32
NextHopIPAddr
The next hop IPv4 address
IPv4Addr
MediaEncapInfoIndex
The index passed onto a downstream encapsulation
LFB, used there as a search key to lookup further
encapsulation information.
uint32
LFBOutputSelectIndex
The index for the IPv4NextHop LFB to choose an
instance in the group output port of the LFB to
output.
uint32
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IPv4NextHopTableType
Data type for IPv4 next hop table in IPv4NextHop LFB.
Entry of the table is of IPv4NextHopInfoType data type.
IPv4NextHopInfoType
IPv6NextHopInfoType
Data type for entry of IPv6 next hop information table
in IPv6NextHop LFB. The table uses a hop selector
received from upstream LFB as a search key to look up
index of the table to find the next hop information.
L3PortID
The ID of the logical output port that is to pass
onto downstream LFB, indicating what port to the
neighbor is as defined by L3.
uint32
MTU
Maximum Transmission Unit for outgoing port
uint32
NextHopIPAddr
The next hop IPv6 address
IPv6Addr
MediaEncapInfoIndex
The index passed onto a downstream encapsulation
LFB, used there as a search key to lookup further
encapsulation information.
uint32
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LFBOutputSelectIndex
The index for the IPv6NextHop LFB to choose an instance
in the group output port of the LFB to output.
uint32
IPv6NextHopTableType
Data type for IPv6 next hop table in IPv6NextHop LFB.
Entry of the table is of IPv6NextHopInfoType data type.
IPv6NextHopInfoType
EncapTableEntryType
Data type for entry of Ethernet encapsulation table in
EtherEncap LFB. The LFB uses the MediaEncapInfoIndex
received from upstream LFB as index of the table to
find encapsulation information of every packet.
DstMac
Destination MAC address for Ethernet encapsulation of
the packet.
IEEEMAC
SrcMac
Source MAC address for Ethernet encapsulation of the
packet.
IEEEMAC
VlanID
The VLAN ID assigned to the packet
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VlanIDType
Reserved
A reserved bit space mainly for purpose of padding
and packing efficiency.
uint16
L2PortID
The L2 logical output port ID for the packet.
uint32
EncapTableType
Data type for Ethernet encapsulation table in Etherencap
LFB. Entry of the table is of EncapTableEntryType data
type.
EncapTableEntryType
MetadataDispatchType
Data type for entry of metadata dispatch table used in
BasicMetadataDispatch LFB. The LFB uses a metadata value
as a search key to look up the table to find an index of
the LFB group output port to output the packet.
MetadataValue
The value of the dispatch metadata
uint32
OutputIndex
Index of a group output port for outgoing packets.
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uint32
MetadataDispatchTableType
Data type for metadata dispatch table used in
BasicMetadataDispatch LFB. Metadata value of
the table is also defined as a content key field.
MetadataDispatchType
MetadataValue
SchdDisciplineType
Scheduling discipline type
uint32
RR
Round Robin scheduling discipline
QueueStatsType
Data type for entry of queue statistics table in
GenericScheduler LFB.
QueueID
The input queue ID
uint32
QueueDepthInPackets
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Current queue depth in packets
uint32
QueueDepthInBytes
Current queue depth in bytes
uint32
QueueStatsTableType
Data type for queue statistics table in GenericScheduler
LFB. Entry of the table is of QueueStatsType data type.
QueueStatsType
PHYPortID
Metadata indicating physical port ID
1
uint32
SrcMAC
Metadata indicating source MAC address
2
IEEEMAC
DstMAC
Metadata indicating destination MAC address.
3
IEEEMAC
LogicalPortID
Metadata of logical port ID
4
uint32
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EtherType
Metadata indicating Ethernet type
5
uint16
VlanID
Metadata of VLAN ID
6
VlanIDType
VlanPriority
Metadata of VLAN priority
7
VlanPriorityType
NextHopIPv4Addr
Metadata representing a next hop IPv4 address
8
IPv4Addr
NextHopIPv6Addr
Metadata representing a next hop IPv6 address
9
IPv6Addr
HopSelector
Metadata indicating a hop selector
10
uint32
ExceptionID
Metadata indicating exception types for exceptional cases
during packet processing.
11
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uint32
AnyUnrecognizedExceptionCase
Any unrecognized exception case
ClassifyNoMatching
Exception case: no matching of tables in
EtherClassifier LFB.
MediaEncapInfoIndexInvalid
Exception case: the MediaEncapInfoIndex value of
the packet is invalid and cannot be allocated in
the EncapTable in EtherEncap LFB.
EncapTableLookupFailed
Exception case: the packet fails lookup of the
EncapTable table in EtherEncap LFB even though the
MediaEncapInfoIndex is valid.
BadTTL
Exception case: packet with expired TTL
IPv4HeaderLengthMismatch
Exception case: packet with header length more
than 5 words.
RouterAlertOptions
Exception case: packet IP head includes router
alert options.
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IPv6HopLimitZero
Exception case: packet with the hop limit to zero.
IPv6NextHeaderHBH
Exception case: packet with next header set to
Hop-by-Hop.
SrcAddressExecption
Exception case: packet with exceptional source
address.
DstAddressExecption
Exception case: packet with exceptional destination
address.
LPMLookupFailed
Exception case: packet failed the LPM table lookup
in a prefix match LFB.
HopSelectorInvalid
Exception case: HopSelector for the packet is
invalid.
NextHopLookupFailed
Exception case: packet failed lookup of a next hop
table even though HopSelector is valid.
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FragRequired
Exception case: packet fragmentation is required
MetadataNoMatching
Exception case: there is no matching when looking
up the metadata dispatch table in
BasicMetadataDispatch LFB.
ValidateErrorID
Metadata indicating error types when a packet passes
validation process.
12
uint32
AnyUnrecognizedValidateErrorCase
Any unrecognized validate error case.
InvalidIPv4PacketSize
Error case: packet length reported by the link
layer is less than 20 bytes.
NotIPv4Packet
Error case: packet is not IP version 4
InvalidIPv4HeaderLengthSize
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Error case: packet with header length field in
the header less than 5 words.
InvalidIPv4LengthFieldSize
Error case: packet with total length field in the
header less than 20 bytes.
InvalidIPv4Checksum
Error case: packet with invalid checksum.
InvalidIPv4SrcAddr
Error case: packet with invalid IPv4 source
address.
InvalidIPv4DstAddr
Error case: packet with invalid IPv4 destination
address.
InvalidIPv6PacketSize
Error case: packet size is less than 40 bytes.
NotIPv6Packet
Error case: packet is not IP version 6
InvalidIPv6SrcAddr
Error case: packet with invalid IPv6 source address.
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InvalidIPv6DstAddr
Error case: packet with invalid IPv6 destination
address.
L3PortID
Metadata indicating ID of an L3 logical port
13
uint32
RedirectIndex
Metadata that CE sends to RedirectIn LFB, indicating
the index of the LFB group output port.
14
uint32
MediaEncapInfoIndex
A search key a packet uses to look up a table to select
an encapsulation media.
15
uint32
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5. LFB Class Description
According to ForCES specifications, LFB (Logical Function Block) is a
well defined, logically separable functional block that resides in an
FE, and is a functionally accurate abstraction of the FE's processing
capabilities. An LFB Class (or type) is a template that represents a
fine-grained, logically separable aspect of FE processing. Most LFBs
are related to packet processing in the data path. LFB classes are
the basic building blocks of the FE model. Note that [RFC5810] has
already defined an 'FE Protocol LFB' which is a logical entity in
each FE to control the ForCES protocol. [RFC5812] has already
defined an 'FE Object LFB'. Information like the FE Name, FE ID, FE
State, LFB Topology in the FE are represented in this LFB.
As specified in Section 3.1, this document focuses on the base LFB
library for implementing typical router functions, especially for IP
forwarding functions. As a result, LFB classes in the library are
all base LFBs to implement router forwarding.
In this section, the terms "upstream LFB" and "downstream LFB" are
used. These are used relative to an LFB to an LFB that is being
described. An "upstream LFB" is one whose output ports are connected
to input ports of the LFB under consideration such that output
(typically packets with metadata) can be sent from the "upstream LFB"
to the LFB under consideration. Similarly, a "downstream LFB" whose
input ports are connected to output ports of the LFB under
consideration such that the LFB under consideration can send
information to the "downstream LFB". Note that in some rare
topologies, an LFB may be both upstream and downstream relative to
another LFB.
Also note that, as a default provision of [RFC5812], in FE model, all
metadata produced by upstream LFBs will pass through all downstream
LFBs by default without being specified by input port or output port.
Only those metadata that will be used (consumed) by an LFB will be
explicitly marked in input of the LFB as expected metadata. For
instance, in downstream LFBs of a physical layer LFB, even there is
no specific metadata expected, metadata like PHYPortID produced by
the physical layer LFB will always pass through all downstream LFBs
regardless of whether the metadata has been expected by the LFBs or
not.
5.1. Ethernet Processing LFBs
As the most popular physical and data link layer protocols, Ethernet
is widely deployed. It becomes a basic requirement for a router to
be able to process various Ethernet data packets.
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Note that there exist different versions of Ethernet formats, like
Ethernet V2, 802.3 RAW, IEEE 802.3/802.2, IEEE 802.3/802.2 SNAP.
There also exist varieties of LAN techniques based on Ethernet, like
various VLANs, MACinMAC, etc. Ethernet processing LFBs defined here
are intended to be able to cope with all these variations of Ethernet
technology.
There are also various types of Ethernet physical interface media.
Among them, copper and fiber media may be the most popular ones. As
a base LFB definition and a starting point, the document only defines
an Ethernet physical LFB with copper media. For other media
interfaces, specific LFBs may be defined in the future versions of
the library.
5.1.1. EtherPHYCop
EtherPHYCop LFB abstracts an Ethernet interface physical layer with
media limited to copper.
5.1.1.1. Data Handling
This LFB is the interface to the Ethernet physical media. The LFB
handles Ethernet frames coming in from or going out of the FE.
Ethernet frames sent and received cover all packets encapsulated with
different versions of Ethernet protocols, like Ethernet V2, 802.3
RAW, IEEE 802.3/802.2,IEEE 802.3/802.2 SNAP, including packets
encapsulated with varieties of LAN techniques based on Ethernet, like
various VLANs, MACinMAC, etc. Therefore in the XML an EthernetAll
frame type has been introduced.
Ethernet frames are received from the physical media port and passed
downstream to LFBs such as EtherMACIn via a singleton output known as
"EtherPHYOut". A 'PHYPortID' metadata, to indicate which physical
port the frame came into from the external world, is passed along
with the frame.
Ethernet packets are received by this LFB from upstream LFBs such as
EtherMacOut LFBs via the singleton input known as "EtherPHYIn" before
being sent out onto the external world.
5.1.1.2. Components
The AdminStatus component is defined for CE to administratively
manage the status of the LFB. The CE may administratively startup or
shutdown the LFB by changing the value of AdminStatus. The default
value is set to 'Down'.
An OperStatus component captures the physical port operational
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status. A PHYPortStatusChanged event is defined so the LFB can
report to the CE whenever there is an operational status change of
the physical port.
The PHYPortID component is a unique identification for a physical
port. It is defined as 'read-only' by CE. Its value is enumerated
by FE. The component will be used to produce a 'PHYPortID' metadata
at the LFB output and to associate it to every Ethernet packet this
LFB receives. The metadata will be handed to downstream LFBs for
them to use the PHYPortID.
A group of components are defined for link speed management. The
AdminLinkSpeed is for CE to configure link speed for the port and the
OperLinkSpeed is for CE to query the actual link speed in operation.
The default value for the AdminLinkSpeed is set to auto-negotiation
mode.
A group of components are defined for duplex mode management. The
AdminDuplexMode is for CE to configure proper duplex mode for the
port and the OperDuplexMode is for CE to query the actual duplex mode
in operation. The default value for the AdminDuplexMode is set to
auto-negotiation mode.
A CarrierStatus component captures the status of the carrier and
specifies whether the port link is operationally up. The default
value for the CarrierStatus is 'false'.
5.1.1.3. Capabilities
The capability information for this LFB includes the link speeds that
are supported by the FE (SupportedLinkSpeed) as well as the supported
duplex modes (SupportedDuplexMode).
5.1.1.4. Events
Several events are generated. There is an event for changes in the
status of the physical port (PhyPortStatusChanged). Such an event
will notify that the physical port status has been changed and the
report will include the new status of the physical port.
Another event captures changes in the operational link speed
(LinkSpeedChanged). Such an event will notify the CE that the
operational speed has been changed and the report will include the
new negotiated operational speed.
A final event captures changes in the duplex mode
(DuplexModeChanged). Such an event will notify the CE that the
duplex mode has been changed and the report will include the new
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negotiated duplex mode.
5.1.2. EtherMACIn
EtherMACIn LFB abstracts an Ethernet port at MAC data link layer.
This LFB describes Ethernet processing functions like MAC address
locality check, deciding if the Ethernet packets should be bridged,
providing Ethernet layer flow control, etc.
5.1.2.1. Data Handling
The LFB is expected to receive all types of Ethernet packets, via a
singleton input known as "EtherPktsIn", which are usually output from
some Ethernet physical layer LFB, like an EtherPHYCop LFB, alongside
with a metadata indicating the physical port ID that the packet
arrived on.
The LFB is defined with two separate singleton outputs. All Output
packets are emitted in the original Ethernet format received at the
physical port, unchanged, and cover all types of Ethernet types.
The first singleton output is known as "NormalPathOut". It usually
outputs Ethernet packets to some LFB like an EtherClassifier LFB for
further L3 forwarding process alongside with a PHYPortID metadata
indicating which physical port the packet came from.
The second singleton output is known as "L2BridgingPathOut".
Although the LFB library this document defines is basically to meet
typical router functions, it will attempt to be forward compatible
with future router functions. The "L2BridgingPathOut" is defined to
meet the requirement that L2 bridging functions may be optionally
supported simultaneously with L3 processing and some L2 bridging LFBs
that may be defined in the future. If the FE supports L2 bridging,
the CE can enable or disable it by means of a "L2BridgingPathEnable"
component in the FE. If it is enabled, by also instantiating some L2
bridging LFB instances following the L2BridgingPathOut, FEs are
expected to fulfill L2 bridging functions. L2BridgingPathOut will
output packets exactly the same as that in the NormalPathOut output.
This LFB can be set to work in a Promiscuous Mode, allowing all
packets to pass through the LFB without being dropped. Otherwise, a
locality check will be performed based on the local MAC addresses.
All packets that do not pass through the locality check will be
dropped.
This LFB can optionally participate in Ethernet flow control in
cooperation with EtherMACOut LFB. This document does not go into the
details of how this is implemented; the reader may refer to some
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relevant references. This document also does not describe how the
buffers which induce the flow control messages behave - it is assumed
that such artifacts exist and describing them is out of scope in this
document.
5.1.2.2. Components
The AdminStatus component is defined for the CE to administratively
manage the status of the LFB. The CE may administratively startup or
shutdown the LFB by changing the value of AdminStatus. The default
value is set to 'Down'.
The LocalMACAddresses component specifies the local MAC addresses
based on which locality checks will be made. This component is an
array of MAC addresses, and of 'read-write' access permission.
An L2BridgingPathEnable component captures whether the LFB is set to
work as a L2 bridge. An FE that does not support bridging will
internally set this flag to false, and additionally set the flag
property as read-only. The default value for is 'false'.
The PromiscuousMode component specifies whether the LFB is set to
work as in a promiscuous mode. The default value for is 'false'.
The TxFlowControl component defines whether the LFB is performing
flow control on sending packets. The default value for is 'false'.
Note that the component is defined as "optional". If an FE does not
implement the component while a CE try to configure the component to
this FE, an error from FE may be responded to CE with error code
like: 0x09(E_COMPONENT_DOES_NOT_EXIST) or 0x15(E_NOT_SUPPORTED)
depending on the FE processing. See [RFC5810] for details.
The RxFlowControl component defines whether the LFB is performing
flow control on receiving packets. The default value for is
'false'.The component is also defined as "optional" one.
A struct component, MACInStats, defines a set of statistics for this
LFB, including the number of received packets and the number of
dropped packets. Note that this statistics component is optional to
implementers. If a CE tries to query the componennt while it is not
implemented in an FE, an error code will be responded to CE
indicating the error type like: 0x09(E_COMPONENT_DOES_NOT_EXIST) or
0x15(E_NOT_SUPPORTED), depending on the FE implementation.
5.1.2.3. Capabilities
This LFB does not have a list of capabilities.
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5.1.2.4. Events
This LFB does not have any events specified.
5.1.3. EtherClassifier
EtherClassifier LFB abstracts the process to decapsulate Ethernet
packets and then classify them.
5.1.3.1. Data Handling
This LFB describes the process of decapsulating Ethernet packets and
classifying them into various network layer data packets according to
information included in the Ethernet packets headers.
The LFB is expected to receive all types of Ethernet packets, via a
singleton input known as "EtherPktsIn", which are usually output from
an upstream LFB like EtherMACIn LFB. This input is also capable of
multiplexing to allow for multiple upstream LFBs being connected.
For instance, when L2 bridging function is enabled in EtherMACIn LFB,
some L2 bridging LFBs may be applied. In this case, some Ethernet
packets after L2 processing may have to be input to EtherClassifier
LFB for classification, while simultaneously packets directly output
from EtherMACIn may also need to input to this LFB. This input is
capable of handling such a case. Usually, all expected Ethernet
Packets will be associated with a PHYPortID metadata, indicating the
physical port the packet comes from. In some cases, for instance,
like in a MACinMAC case, a LogicalPortID metadata may be expected to
associate with the Ethernet packet to further indicate which logical
port the Ethernet packet belongs to. Note that PHYPortID metadata is
always expected while LogicalPortID metadata is optionally expected.
Two output LFB ports are defined.
The first output is a group output port known as "ClassifyOut".
Types of network layer protocol packets are output to instances of
the port group. Because there may be various type of protocol
packets at the output ports, the produced output frame is defined as
arbitrary for the purpose of wide extensibility in the future.
Metadata to be carried along with the packet data is produced at this
LFB for consumption by downstream LFBs. The metadata passed
downstream includes PHYPortID, as well as information on Ethernet
type, source MAC address, destination MAC address and the logical
port ID. If the original packet is a VLAN packet and contains a VLAN
ID and a VLAN priority value, then the VLAN ID and the VLAN priority
value are also carried downstream as metadata. As a result, the VLAN
ID and priority metadata are defined with the availability of
"conditional".
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The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types include:
o There is no matching when classifying the packet.
Usually the exception out port may point to no where, indicating
packets with exceptions are dropped, while in some cases, the output
may be pointed to the path to the CE for further processing,
depending on individual implementations.
5.1.3.2. Components
An EtherDispatchTable array component is defined in the LFB to
dispatch every Ethernet packet to the output group according to the
logical port ID assigned by the VlanInputTable to the packet and the
Ethernet type in the Ethernet packet header. Each row of the array
is a struct containing a Logical Port ID, an EtherType and an Output
Index. With the CE configuring the dispatch table, the LFB can be
expected to classify various network layer protocol type packets and
output them at different output ports. It is expected that the LFB
classify packets according to protocols like IPv4, IPv6, MPLS, ARP,
ND, etc.
A VlanInputTable array component is defined in the LFB to classify
VLAN Ethernet packets. Each row of the array is a struct containing
an Incoming Port ID, a VLAN ID and a Logical Port ID. According to
IEEE VLAN specifications, all Ethernet packets can be recognized as
VLAN types by defining that if there is no VLAN encapsulation in a
packet, a case with VLAN tag 0 is considered. Every input packet is
assigned with a new LogicalPortID according to the packet incoming
port ID and the VLAN ID. A packet incoming port ID is defined as a
logical port ID if a logical port ID is associated with the packet,
or a physical port ID if no logical port ID associated. The VLAN ID
is exactly the VLAN ID in the packet if it is a VLAN packet, or 0 if
it is not. Note that a logical port ID of a packet may be rewritten
with a new one by the VlanInputTable processing.
Note that the logical port ID and physical port ID mentioned above
are all originally configured by CE, and are globally effective
within a ForCES NE (Network Element). To distinguish a physical port
ID from a logical port ID in the incoming port ID field of the
VlanInputTable, physical port ID and logical port ID must be assigned
with separate number spaces.
An array component, EtherClassifyStats, defines a set of statistics
for this LFB, measuring the number of packets per EtherType. Each
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row of the array is a struct containing an EtherType and a Packet
number.Note that this statistics component is optional to
implementers.
5.1.3.3. Capabilities
This LFB does not have a list of capabilities.
5.1.3.4. Events
This LFB has no events specified.
5.1.4. EtherEncap
The EtherEncap LFB abstracts the process to replace or attach
appropriate Ethernet headers to the packet.
5.1.4.1. Data Handling
This LFB abstracts the process of encapsulating Ethernet headers onto
received packets. The encapsulation is based on passed metadata.
The LFB is expected to receive IPv4 and IPv6 packets, via a singleton
input port known as "EncapIn" which may be connected to an upstream
LFB like an IPv4NextHop, an IPv6NextHop, BasicMetadataDispatch, or
any LFB which requires to output packets for Ethernet encapsulation.
The LFB always expects from upstream LFBs the MediaEncapInfoIndex
metadata which is used as a search key to lookup the encapsulation
table EncapTable by the search key matching the table index. An
input packet may also optionally receive a VLAN priority metadata,
indicating that the packet is originally with a priority value. The
priority value will be loaded back to the packet when encapsulating.
The optional VLAN priority metadata is defined with a default value
0.
Two singleton output LFB ports are defined.
The first singleton output known as "SuccessOut". Upon a successful
table lookup, the destination and source MAC addresses, and the
logical media port (L2PortID) are found in the matching table entry.
The CE may set the VlanID in case VLANs are used. By default the
table entry for VlanID of 0 is used as per IEEE rules. Whatever the
value of VlanID is, if the input metadata VlanPriority is non-zero,
the packet will have a VLAN tag. If the VlanPriority and the VlanID
are all zero, there is no VLAN tag to this packet. After replacing
or attaching the appropriate Ethernet headers to the packet is
complete, the packet is passed out on the "SuccessOut" LFB port to a
downstream LFB instance alongside with the L2PortID.
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The second singleton output known as "ExceptionOut", which will
output packets for which the table lookup fails, along with an
additional ExceptionID metadata. Currently defined exception types
only include the following case:
o The MediaEncapInfoIndex value of the packet is invalid and can not
be allocated in the EncapTable.
o The packet failed lookup of the EncapTable table even though the
MediaEncapInfoIndex is valid.
The upstream LFB may be programmed by the CE to pass along a
MediaEncapInfoIndex that does not exist in the EncapTable. That is
to allow for resolution of the L2 headers, if needed, to be made at
the L2 encapsulation level in this case (Ethernet) via ARP, or ND (or
other methods depending on the link layer technology) when a table
miss occurs.
For neighbor L2 header resolution(table miss exception), the
processing LFB may pass this packet to the CE via the redirect LFB or
FE software or another LFB instance for further resolution. In such
a case the metadata NextHopIPv4Addr or NextHopIPv6Addr generated by
next hop LFB is also passed to the exception handling. Such an IP
address could be used to do activities such as ARP or ND by the
handler it is passed to.
The result of the L2 resolution is to update the EncapTable as well
as the next hop LFB so subsequent packets do not fail EncapTable
lookup. The EtherEncap LFB does not make any assumptions of how the
EncapTable is updated by the CE (or whether ARP/ND is used
dynamically or static maps exist).
Downstream LFB instances could be either an EtherMACOut type or a
BasicMetadataDispatch type. If the final packet L2 processing is
possible to be on per-media-port basis or resides on a different FE
or in cases where L2 header resolution is needed, then the model
makes sense to use a BasicMetadataDispatch LFB to fan out to
different LFB instances. If there is a direct egress port point,
then the model makes sense to have a downstream LFB instance being an
EtherMACOut.
5.1.4.2. Components
This LFB has only one component named EncapTable which is defined as
an array. Each row of the array is a struct containing the
destination MAC address, the source MAC address, the VLAN ID with a
default value of zero and the output logical L2 port ID.
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5.1.4.3. Capabilities
This LFB does not have a list of capabilities.
5.1.4.4. Events
This LFB does not have any events specified.
5.1.5. EtherMACOut
EtherMACOut LFB abstracts an Ethernet port at MAC data link layer.
This LFB describes Ethernet packet output process. Ethernet output
functions are closely related to Ethernet input functions, therefore
many components defined in this LFB are as aliases of EtherMACIn LFB
components.
5.1.5.1. Data Handling
The LFB is expected to receive all types of Ethernet packets, via a
singleton input known as "EtherPktsIn", which are usually output from
an Ethernet encapsulation LFB, alongside with a metadata indicating
the physical port ID that the packet will go through.
The LFB is defined with a singleton output port known as
"EtherPktsOut". All Output packets are in Ethernet format, possibly
with various Ethernet types, alongside with a metadata indicating the
physical port ID the packet is to go through. This output links to a
downstream LFB that is usually an Ethernet physical LFB like
EtherPHYcop LFB.
This LFB can optionally participate in Ethernet flow control in
cooperation with EtherMACIn LFB. This document does not go into the
details of how this is implemented; the reader may refer to some
relevant references. This document also does not describe how the
buffers which induce the flow control messages behave - it is assumed
that such artifacts exist and describing them is out of scope in this
document.
Note that as a base definition, functions like multiple virtual MAC
layers are not supported in this LFB version. It may be supported in
the future by defining a subclass or a new version of this LFB.
5.1.5.2. Components
The AdminStatus component is defined for CE to administratively
manage the status of the LFB. The CE may administratively startup or
shutdown the LFB by changing the value of AdminStatus. The default
value is set to 'Down'. Note that this component is defined as an
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alias of the AdminStatus component in the EtherMACIn LFB. This
infers that an EtherMACOut LFB usually coexists with an EtherMACIn
LFB, both of which share the same administrative status management by
CE. Alias properties as defined in the ForCES FE model [RFC5812]
will be used by CE to declare the target component this alias refers,
which include the target LFB class and instance IDs as well as the
path to the target component.
The MTU component defines the maximum transmission unit.
The optinal TxFlowControl component defines whether the LFB is
performing flow control on sending packets. The default value for is
'false'. Note that this component is defined as an alias of
TxFlowControl component in the EtherMACIn LFB.
The optional RxFlowControl component defines whether the LFB is
performing flow control on receiving packets. The default value for
is 'false'. Note that this component is defined as an alias of
RxFlowControl component in the EtherMACIn LFB.
A struct component, MACOutStats, defines a set of statistics for this
LFB, including the number of transmitted packets and the number of
dropped packets. This statistics component is optional to
impleneters.
5.1.5.3. Capabilities
This LFB does not have a list of capabilities.
5.1.5.4. Events
This LFB does not have any events specified.
5.2. IP Packet Validation LFBs
The LFBs are defined to abstract IP packet validation process. An
IPv4Validator LFB is specifically for IPv4 protocol validation and an
IPv6Validator LFB for IPv6.
5.2.1. IPv4Validator
The IPv4Validator LFB performs IPv4 packets validation.
5.2.1.1. Data Handling
This LFB performs IPv4 validation according to [RFC1812] and its
updates. The IPv4 packet will be output to the corresponding LFB
port the indication whether the packet is unicast, multicast or
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whether an exception has occurred or the validation failed.
This LFB always expects, as input, packets which have been indicated
as IPv4 packets by an upstream LFB, like an EtherClassifier LFB.
There is no specific metadata expected by the input of the LFB.
Four output LFB ports are defined.
All validated IPv4 unicast packets will be output at the singleton
port known as "IPv4UnicastOut". All validated IPv4 multicast packets
will be output at the singleton port known as "IPv4MulticastOut"
port.
A singleton port known as "ExceptionOut" is defined to output packets
which have been validated as exception packets. An exception ID
metadata is produced to indicate what has caused the exception. An
exception case is the case when a packet needs further processing
before being normally forwarded. Currently defined exception types
include:
o Packet with expired TTL
o Packet with header length more than 5 words
o Packet IP head including Router Alert options
o Packet with exceptional source address
o Packet with exceptional destination address
Note that although TTL is checked in this LFB for validity,
operations like TTL decrement are made by the downstream forwarding
LFB.
The final singleton port known as "FailOut" is defined for all
packets which have errors and failed the validation process. An
error case is the case when a packet is unable to be further
processed nor forwarded except being dropped. An error ID is
associated a packet to indicate the failure reason. Currently
defined failure reasons include:
o Packet with size reported less than 20 bytes
o Packet with version is not IPv4
o Packet with header length less than 5 words
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o Packet with total length field less than 20 bytes
o Packet with invalid checksum
o Packet with invalid source address
o Packet with invalid destination address
5.2.1.2. Components
This LFB has only one struct component, the
IPv4ValidatorStatisticsType, which defines a set of statistics for
validation process, including the number of bad header packets, the
number of bad total length packets, the number of bad TTL packets,
and the number of bad checksum packets. This statistics componennt
is optional to implementers.
5.2.1.3. Capabilities
This LFB does not have a list of capabilities
5.2.1.4. Events
This LFB does not have any events specified.
5.2.2. IPv6Validator
The IPv6Validator LFB performs IPv6 packets validation.
5.2.2.1. Data Handling
This LFB performs IPv6 validation according to [RFC2460] and its
updates. Then the IPv6 packet will be output to the corresponding
port regarding of the validation result, whether the packet is a
unicast or a multicast one, an exception has occurred or the
validation failed.
This LFB always expects, as input, packets which have been indicated
as IPv6 packets by an upstream LFB, like an EtherClassifier LFB.
There is no specific metadata expected by the input of the LFB.
Similar to the IPv4validator LFB, IPv6Validator LFB has also defined
four output ports to emit packets with various validation results.
All validated IPv6 unicast packets will be output at the singleton
port known as "IPv6UnicastOut". All validated IPv6 multicast packets
will be output at the singleton port known as "IPv6MulticastOut"
port. There is no metadata produced at this LFB.
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A singleton port known as "ExceptionOut" is defined to output packets
which have been validated as exception packets. An exception case is
the case when a packet needs further processing before being normally
forwarded. An exception ID metadata is produced to indicate what
caused the exception. Currently defined exception types include:
o Packet with hop limit to zero
o Packet with next header set to Hop-by-Hop
o Packet with exceptional source address
o Packet with exceptional destination address
The final singleton port known as "FailOut" is defined for all
packets which have errors and failed the validation process. An
error case is the case when a packet is unable to be further
processed nor forwarded except being dropped. A validate error ID is
associated to every failed packet to indicate the reason. Currently
defined reasons include:
o Packet with size reported less than 40 bytes
o Packet with not IPv6 version
o Packet with invalid source address
o Packet with invalid destination address
Note that in the base type library, definitions for exception ID and
validate error ID metadata are applied to both IPv4Validator and
IPv6Validator LFBs, i.e., the two LFBs share the same medadata
definition, with different ID assignment inside.
5.2.2.2. Components
This LFB has only one struct component, the
IPv6ValidatorStatisticsType, which defines a set of statistics for
validation process, including the number of bad header packets, the
number of bad total length packets, and the number of bad hop limit
packets. Note that this component is optional to implementers.
5.2.2.3. Capabilities
This LFB does not have a list of capabilities
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5.2.2.4. Events
This LFB does not have any events specified.
5.3. IP Forwarding LFBs
IP Forwarding LFBs are specifically defined to abstract the IP
forwarding processes. As definitions for a base LFB library, this
document restricts its LFB definition scope only to IP unicast
forwarding. IP multicast may be defined in future documents.
The two fundamental tasks performed in IP unicast forwarding
constitute looking up the forwarding information table to find next
hop information, and then using the resulting next hop details to
forward packets out on specific physical output ports. This document
models the forwarding processes by abstracting out the described two
steps. Whereas this document describes functional LFB models which
are modular, there may be multiple ways to implement the abstracted
models. It is not intended nor expected that the provided LFB models
constrain implementations.
Based on the IP forwarding abstraction, two kind of typical IP
unicast forwarding LFBs are defined, Unicast LPM lookup LFB and next
hop application LFB. They are further distinguished by IPv4 and IPv6
protocols.
5.3.1. IPv4UcastLPM
The IPv4UcastLPM LFB abstracts the IPv4 unicast Longest Prefix Match
(LPM) process.
This LFB also provides facilities to support users to implement
equal-cost multi-path routing (ECMP) or reverse path forwarding
(RPF). However, this LFB itself does not provide ECMP or RPF. To
fully implement ECMP or RPF, additional specific LFBs, like a
specific ECMP LFB or an RPF LFB, will have to be defined.
5.3.1.1. Data Handling
This LFB performs the IPv4 unicast LPM table looking up. It always
expects as input IPv4 unicast packets from one singleton input known
as "PktsIn". Then the LFB uses the destination IPv4 address of every
packet as search key to look up the IPv4 prefix table and generate a
hop selector as the matching result. The hop selector is passed as
packet metadata to downstream LFBs, and will usually be used there as
a search index to find more next hop information.
Three singleton output LFB ports are defined.
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The first singleton output known as "NormalOut" outputs IPv4 unicast
packets that succeed the LPM lookup and (got a hop selector). The
hop selector is associated with the packet as a metadata. Downstream
from the LPM LFB is usually a next hop application LFB, like an
IPv4NextHop LFB.
The second singleton output known as "ECMPOut" is defined to provide
support for users wishing to implement ECMP.
An ECMP flag is defined in the LPM table to enable the LFB to support
ECMP. When a table entry is created with the flag set true, it
indicates this table entry is for ECMP only. A packet, which has
passed through this prefix lookup, will always output from "ECMPOut"
output port, with the hop selector being its lookup result. The
output will usually directly go to a downstream ECMP processing LFB,
where the hop selector can usually further generate optimized one or
multiple next hop routes by use of ECMP algorithms.
A default route flag is defined in the LPM table to enable the LFB to
support a default route as well as loose RPF. When this flag is set
true, the table entry is identified a default route which also
implies that the route is forbidden for RPF. If a user wants to
implement RPF on FE, a specific RPF LFB will have to be defined. In
such RPF LFB, a component can be defined as an alias of the prefix
table component of this LFB as described below.
The final singleton output is known as "ExceptionOut" and is defined
to allow exception packets to output here, along with an ExceptionID
metadata to indicate what caused the exception. Currently defined
exception types include:
o The packet failed the LPM lookup of the prefix table.
The upstream LFB of this LFB is usually IPv4Validator LFB. If RPF is
to be adopted, the upstream can be an RPF LFB, when defined.
The downstream LFB is usually IPv4NextHop LFB. If ECMP is adopted,
the downstream can be an ECMP LFB, when defined.
5.3.1.2. Components
This LFB has two components.
The IPv4PrefixTable component is defined as an array component of the
LFB. Each row of the array contains an IPv4 address, a Prefix
length, a Hop Selector, an ECMP flag and a Default Route flag. The
LFB uses the destination IPv4 address of every input packet as search
key to look up this table in order extract a next hop selector. The
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ECMP flag is for the LFB to support ECMP. The default route flag is
for the LFB to support a default route and for loose RPF.
The IPv4UcastLPMStats component is a struct component which collects
statistics information, including the total number of input packets
received, the IPv4 packets forwarded by this LFB and the number of IP
datagrams discarded due to no route found.Note the component is
defined as optional to implementers.
5.3.1.3. Capabilities
This LFB does not have a list of capabilities
5.3.1.4. Events
This LFB does not have any events specified.
5.3.2. IPv4NextHop
This LFB abstracts the process of selecting ipv4 next hop action.
5.3.2.1. Data Handling
The LFB abstracts the process of next hop information application to
IPv4 packets. It receives an IPv4 packet with an associated next hop
identifier (HopSelector), and uses the identifier as a table index to
look up a next hop table to find an appropriate LFB output port.
The LFB is expected to receive unicast IPv4 packets, via a singleton
input known as "PktsIn" along with a HopSelector metadata which is
used as a table index to lookup the NextHop table. The data
processing involves the forwarding TTL decrement and IP checksum
recalculation.
Two output LFB ports are defined.
The first output is a group output port known as "SuccessOut". On
successful data processing the packet is sent out an LFB-port from
within the LFB port group as selected by the LFBOutputSelectIndex
value of the matched table entry. The packet is sent to a downstream
LFB alongside with the L3PortID and MediaEncapInfoIndex metadata.
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types include:
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o The HopSelector for the packet is invalid.
o The packet failed lookup of the next hop table even though the
HopSelector is valid.
o The MTU for outgoing interface is less than the packet size.
Downstream LFB instances could be either a BasicMetadataDispatch type
(Section 5.5.1), used to fan out to different LFB instances or a
media encapsulation related type, such as an EtherEncap type or a
RedirectOut type(Section 5.4.2). For example, if there are Ethernet
and other tunnel Encapsulation, then a BasicMetadataDispatch LFB can
use the L3PortID metadata (Section 5.3.2.2) to dispatch packets to
different encapsulator.
5.3.2.2. Components
This LFB has only one component named IPv4NextHopTable which is
defined as an array. The HopSelector received is used to match the
array index of IPv4NextHopTable to find out a row of the table as the
next hop information result. Each row of the array is a struct
containing:
o The L3PortID, which is the ID of the Logical Output Port that is
passed onto the downstream LFB instance. This ID indicates what
port to the neighbor is as defined by L3. Usually this ID is used
for the next hop LFB to distinguish packets that need different L2
encapsulating. For instance, some packets may require general
Ethernet encapsulation while others may require various types of
tunnel encapsulations. In such case, different L3PortIDs are
assigned to the packets and are as metadata passed to downstream
LFB. A BasicMetadataDispatch LFB(Section 5.5.1) may have to be
applied as the downstream LFB so as to dispatch packets to
different encapsulation LFB instances according to the L3PortIDs.
o MTU, the Maximum Transmission Unit for the outgoing port.
o NextHopIPAddr, the IPv4 next hop address.
o MediaEncapInfoIndex, the index we pass onto the downstream
encapsulation LFB instance and that is used there as a search key
to lookup a table (typically media encapsulation related) for
further encapsulation information. The search key looks up the
table by matching the table index.Note that an encapsulation LFB
instance may not directly follow the next hop LFB, but the index
is passed as a metadata associated, as such an encapsulation LFB
instance even further downstream to the next hop LFB can still use
the index. In some cases, depending on implementation, the CE may
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set the MediaEncapInfoIndex passed downstream to a value that will
fail lookup when it gets to a target encapsulation LFB; such a
lookup failure at that point is an indication that further
resolution is needed. For an example of this approach refer to
Section 7.2 which talks about ARP and mentions this approach.
o LFBOutputSelectIndex, the LFB Group output port index to select
downstream LFB port. It is a 1-to-1 mapping with FEObject LFB's
table LFBTopology (See [RFC5812]) component FromPortIndex
corresponding to the port group mapping FromLFBID as IPv4NextHop
LFB instance.
5.3.2.3. Capabilities
This LFB does not have a list of capabilities
5.3.2.4. Events
This LFB does not have any events specified.
5.3.3. IPv6UcastLPM
The IPv6UcastLPM LFB abstracts the IPv6 unicast Longest Prefix Match
(LPM) process. The definition of this LFB is similar to the
IPv4UcastLPM LFB except that all IP addresses refer to IPv6
addresses.
This LFB also provides facilities to support users to implement
equal-cost multi-path routing (ECMP) or reverse path forwarding
(RPF). However, this LFB itself does not provide ECMP or RPF. To
fully implement ECMP or RPF, additional specific LFBs, like a
specific ECMP LFB or an RPF LFB, will have to be defined. This work
may be done in the future version of the document.
5.3.3.1. Data Handling
This LFB performs the IPv6 unicast LPM table look up. It always
expects as input IPv6 unicast packets from one singleton input known
as "PktsIn". The destination IPv6 address of an incoming packet is
used as search key to look up the IPv6 prefix table and generate a
hop selector. This hop selector result is associated to the packet
as a metadata and sent to downstream LFBs, and will usually be used
in downstream LFBs as a search key to find more next hop information.
Three singleton output LFB ports are defined.
The first singleton output known as "NormalOut" outputs IPv6 unicast
packets that succeed the LPM lookup (and got a hop selector). The
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hop selector is associated with the packet as a metadata. Downstream
from the LPM LFB is usually a next hop application LFB, like an
IPv6NextHop LFB.
The second singleton output known as "ECMPOut" is defined to provide
support for users wishing to implement ECMP.
An ECMP flag is defined in the LPM table to enable the LFB to support
ECMP. When a table entry is created with the flag set true, it
indicates this table entry is for ECMP only. A packet, which has
passed through this prefix lookup, will always output from "ECMPOut"
output port, with the hop selector being its lookup result. The
output will usually directly go to a downstream ECMP processing LFB,
where the hop selector can usually further generate optimized one or
multiple next hop routes by use of ECMP algorithms.
A default route flag is defined in the LPM table to enable the LFB to
support a default route as well as loose RPF. When this flag is set
true, the table entry is identified a default route which also
implies that the route is forbidden for RPF.
If a user wants to implement RPF on FE, a specific RPF LFB will have
to be defined. In such RPF LFB, a component can be defined as an
alias of the prefix table component of this LFB as described below.
The final singleton output is known as "ExceptionOut" and is defined
to allow exception packets to output here, along with an ExceptionID
metadata to indicate what caused the exception. Currently defined
exception types include:
o The packet failed the LPM lookup of the prefix table.
The upstream LFB of this LFB is usually IPv6Validator LFB. If RPF is
to be adopted, the upstream can be an RPF LFB, when defined.
The downstream LFB is usually an IPv6NextHop LFB. If ECMP is
adopted, the downstream can be an ECMP LFB, when defined.
5.3.3.2. Components
This LFB has two components.
The IPv6PrefixTable component is defined as an array component of the
LFB. Each row of the array contains an IPv6 address, a Prefix
length, a Hop Selector, an ECMP flag and a Default Route flag. The
ECMP flag is so the LFB can support ECMP. The default route flag is
for the LFB to support a default route and for loose RPF as described
earlier.
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The IPv6UcastLPMStats component is a struct component which collects
statistics information, including the total number of input packets
received, the IPv6 packets forwarded by this LFB and the number of IP
datagrams discarded due to no route found.Note the component is
defined as optional to implementers.
5.3.3.3. Capabilities
This LFB does not have a list of capabilities
5.3.3.4. Events
This LFB does not have any events specified.
5.3.4. IPv6NextHop
This LFB abstracts the process of selecting IPv6 next hop action.
5.3.4.1. Data Handling
The LFB abstracts the process of next hop information application to
IPv6 packets. It receives an IPv6 packet with an associated next hop
identifier (HopSelector), and uses the identifier to look up a next
hop table to find an appropriate output port from the LFB.
The LFB is expected to receive unicast IPv6 packets, via a singleton
input known as "PktsIn" along with a HopSelector metadata which is
used as a table index to lookup the next hop table.
Two output LFB ports are defined.
The first output is a group output port known as "SuccessOut". On
successful data processing the packet is sent out an LFB port from
within the LFB port group as selected by the LFBOutputSelectIndex
value of the matched table entry. The packet is sent to a downstream
LFB alongside with the L3PortID and MediaEncapInfoIndex metadata.
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types include:
o The HopSelector for the packet is invalid.
o The packet failed lookup of the next hop table even though the
HopSelector is valid.
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o The MTU for outgoing interface is less than the packet size.
Downstream LFB instances could be either a BasicMetadataDispatch
type, used to fan out to different LFB instances or a media
encapsulatation related type, such as an EtherEncap type or a
RedirectOut type. For example, when the downstream LFB is
BasicMetadataDispatch, and there exist Ethernet and other tunnel
Encapsulation downstream from BasicMetadataDispatch, then the
BasicMetadataDispatch LFB can use the L3PortID metadata (See section
below) to dispatch packets to the different encapsulator LFBs.
5.3.4.2. Components
This LFB has only one component named IPv6NextHopTable which is
defined as an array. The array index of IPv6NextHopTable is used for
a HopSelector to find out a row of the table as the next hop
information. Each row of the array is a struct containing:
o The L3PortID, which is the ID of the Logical Output Port that is
passed onto the downstream LFB instance. This ID indicates what
port to the neighbor is as defined by L3. Usually this ID is used
for the next hop LFB to distinguish packets that need different L2
encapsulating. For instance, some packets may require general
Ethernet encapsulation while others may require various types of
tunnel encapsulations. In such case, different L3PortIDs are
assigned to the packets and are as metadata passed to downstream
LFB. A BasicMetadataDispatch LFB(Section 5.5.1) may have to be
applied as the downstream LFB so as to dispatch packets to
different encapsulation LFB instances according to the L3PortIDs.
o MTU, the Maximum Transmission Unit for the outgoing port.
o NextHopIPAddr, the IPv6 next hop address.
o MediaEncapInfoIndex, the index we pass onto the downstream
encapsulation LFB instance and that is used there as a search key
to lookup a table (typically media encapsulation related) for
further encapsulation information. The saearch key looks up the
table by matching the table index. Note that an encapsulation LFB
instance may not directly follow the next hop LFB, but the index
is passed as a metadata associated, as such an encapsulation LFB
instance even further downstream to the next hop LFB can still use
the index. In some cases, depending on implementation, the CE may
set the MediaEncapInfoIndex passed downstream to a value that will
fail lookup when it gets to a target encapsulation LFB; such a
lookup failure at that point is an indication that further
resolution is needed. For an example of this approach refer to
Section 7.2 which talks about ARP and mentions this approach.
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o LFBOutputSelectIndex, the LFB Group output port index to select
downstream LFB port. It is a 1-to-1 mapping with FEObject LFB's
table LFBTopology (See [RFC5812]) component FromPortIndex
corresponding to the port group mapping FromLFBID as IPv4NextHop
LFB instance.
5.3.4.3. Capabilities
This LFB does not have a list of capabilities
5.3.4.4. Events
This LFB does not have any events specified.
5.4. Redirect LFBs
Redirect LFBs abstract data packets transportation process between CE
and FE. Some packets output from some LFBs may have to be delivered
to CE for further processing, and some packets generated by CE may
have to be delivered to FE and further to some specific LFBs for data
path processing. According to [RFC5810], data packets and their
associated metadata are encapsulated in ForCES redirect message for
transportation between CE and FE. We define two LFBs to abstract the
process, a RedirectIn LFB and a RedirectOut LFB. Usually, in an LFB
topology of an FE, only one RedirectIn LFB instance and one
RedirectOut LFB instance exist.
5.4.1. RedirectIn
RedirectIn LFB abstracts the process for the CE to inject data
packets into the FE data path.
5.4.1.1. Data Handling
A RedirectIn LFB abstracts the process for the CE to inject data
packets into the FE LFB topology so as to input data packets into FE
data paths. From LFB topology point of view, the RedirectIn LFB acts
as a source point for data packets coming from CE, therefore
RedirectIn LFB is defined with a single output LFB port (and no input
LFB port).
The single output port of RedirectIn LFB is defined as a group output
type, with the name of "PktsOut". Packets produced by this output
will have arbitrary frame types decided by the CE which generated the
packets. Possible frames may include IPv4, IPv6, or ARP protocol
packets. The CE may associate some metadata to indicate the frame
types and may also associate other metadata to indicate various
information on the packets. Among them, there MUST exist a
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'RedirectIndex' metadata, which is an integer acting as an index.
When the CE transmits the metadata along with the packet to a
RedirectIn LFB, the LFB will read the RedirectIndex metadata and
output the packet to one of its group output port instance, whose
port index is indicated by this metadata. Any other metadata, in
addition to 'RedirectIndex', will be passed untouched along the
packet delivered by the CE to downstream LFB. This means the
'RedirectIndex' metadata from CE will be "consumed" by the RedirectIn
LFB and will not be passed to downstream LFB. Note that, a packet
from CE without a 'RedirectIndex' metadata associated will be dropped
by the LFB. Note that all metadata visible to the LFB need to be
global and IANA controlled. See the "IANA Considerations" of the
document for more details, where a metadata ID private space that can
be used by vendors is also provided.
5.4.1.2. Components
An optional statistics component is defined to collect the number of
packets received by the LFB from CE. There are no other components
defined for current version of the LFB.
5.4.1.3. Capabilities
This LFB does not have a list of capabilities
5.4.1.4. Events
This LFB does not have any events specified.
5.4.2. RedirectOut
RedirectOut LFB abstracts the process for LFBs in the FE to deliver
data packets to the CE.
5.4.2.1. Data Handling
A RedirectOut LFB abstracts the process for LFBs in the FE to deliver
data packets to the CE. From the LFB's topology point of view, the
RedirectOut LFB acts as a sink point for data packets going to the
CE, therefore RedirectOut LFB is defined with a single input LFB port
(and no output LFB port).
The RedirectOut LFB has only one singleton input known as "PktsIn",
but is capable of receiving packets from multiple LFBs by
multiplexing this input. The input expects any kind of frame type
therefore the frame type has been specified as arbitrary, and also
all types of metadata are expected. All associated metadata produced
(but not consumed) by previous processed LFBs should be delivered to
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CE via the ForCES protocol redirect message [RFC5810]. The CE can
decide on how to process the redirected packet by referencing the
associated metadata. As an example, a packet could be redirected by
the FE to the CE because the EtherEncap LFB is not able to resolve L2
information. The metadata "ExceptionID", created by the EtherEncap
LFB is passed along with the packet and should be sufficient for the
CE to do the necessary processing and resolve the L2 entry required.
Note that all metadata visible to the LFB need to be global and IANA
controlled. See the "IANA Considerations" of the document for more
details, where a metadata ID private space that can be used by
vendors is also provided.
5.4.2.2. Components
An optional statistics component is defined to collect the number of
packets sent by the LFB to CE. There are no other components defined
for current version of the LFB.
5.4.2.3. Capabilities
This LFB does not have a list of capabilities
5.4.2.4. Events
This LFB does not have any events specified.
5.5. General Purpose LFBs
5.5.1. BasicMetadataDispatch
The BasicMetadataDispatch LFB is defined to abstract the process in
which a packet is dispatched to some output path based on its
associated metadata value.
5.5.1.1. Data Handling
The BasicMetadataDispatch has only one singleton input known as
"PktsIn". Every input packet should be associated with a metadata
that will be used by the LFB to do the dispatch. This LFB contains a
metadata ID and a dispatch table named MetadataDispatchTable, all
configured by the CE. The metadata ID specifies which metadata is to
be used for dispatching packets. The MetadataDispatchTable contains
entries of a metadata value and an OutputIndex, specifying that the
packet with the metadata value must go out from the LFB group output
port instance with the OutputIndex.
Two output LFB ports are defined.
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The first output is a group output port known as "PktsOut". A packet
with its associated metadata having found an OutputIndex by
successfully looking up the dispatch table will be output to the
group port instance with the corresponding index.
The second output is a singleton output port known as "ExceptionOut",
which will output packets for which the data processing failed, along
with an additional ExceptionID metadata to indicate what caused the
exception. Currently defined exception types only include one case:
o There is no matching when looking up the metadata dispatch table.
As an example, if the CE decides to dispatch packets according to a
physical port ID (PHYPortID), the CE may set the ID of PHYPortID
metadata to the LFB first. Moreover, the CE also sets the PHYPortID
actual values (the metadata values) and assigned OutputIndex for the
values to the dispatch table in the LFB. When a packet arrives, a
PHYPortID metadata is found associated with the packet, the metadata
value is further used as a key to look up the dispatch table to find
out an output port instance for the packet.
Currently the BasicMetadataDispatch LFB only allows the metadata
value of the dispatch table entry be 32-bits integer. A metadata
with other types of value is not supported in this version. A more
complex metadata dispatch LFB may be defined in future version of the
library. In that LFB, multiple tuples of metadata with more value
types supported may be used to dispatch packets.
5.5.1.2. Components
This LFB has two components. One component is MetadataID and the
other is MetadataDispatchTable. Each row entry of the dispatch table
is a struct containing metadata value and the OutputIndex. Note that
currently, the metadata value is only allowed to be 32-bits integer.
The metadata value is also defined as a content key for the table.
The concept of content key is a searching key for tables which is
defined in the ForCES FE Model [RFC5812]. With the content key, CE
can manipulate the table by means of a specific metadata value rather
than by the table index only. See [RFC5812] document and also the
ForCES Protocol [RFC5810] for more details on the definition and use
of a content key.
5.5.1.3. Capabilities
This LFB does not have a list of capabilities
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5.5.1.4. Events
This LFB does not have any events specified.
5.5.2. GenericScheduler
This is a preliminary generic scheduler LFB for abstracting a simple
scheduling process.
5.5.2.1. Data Handling
There exist various kinds of scheduling strategies with various
implementations. As a base LFB library, this document only defines a
preliminary generic scheduler LFB for abstracting a simple scheduling
process. Users may use this LFB as a basic LFB to further construct
more complex scheduler LFBs by means of "inheritance" as described in
[RFC5812].
Packets of any arbitrary frame type are received via a group input
known as "PktsIn" with no additional metadata expected. This group
input is capable of multiple input port instances. Each port
instance may be connected to different upstream LFB output. Inside
the LFB, it is abstracted that each input port instance is connected
to a queue, and the queue is marked with a queue ID whose value is
exactly the same as the index of corresponding group input port
instance. Scheduling disciplines are applied to all queues and also
all packets in the queues.The group input port property
PortGroupLimits in ObjectLFB as defined by ForCES FE model[RFC5810]
provides means for the CE to query the capability of total queue
numbers the scheduler supports. The CE can then decide how many
queues it may use for a scheduling application.
Scheduled packets are output from a singleton output port of the LFB
knows as "PktsOut" with no corresponding metadata.
More complex scheduler LFBs may be defined with more complex
scheduling disciplines by succeeding this LFB. For instance, a
priority scheduler LFB may be defined by inheriting this LFB and
defining a component to indicate priorities for all input queues.
5.5.2.2. Components
The SchedulingDiscipline component is for the CE to specify a
scheduling discipline to the LFB. Currently defined scheduling
disciplines only include Round Robin (RR) strategy. The default
scheduling discipline is RR then.
The QueueStats component is defined to allow CE to query every queue
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status of the scheduler. It is an array component and each row of
the array is a struct containing a queue ID. Currently defined queue
status includes the queue depth in packets and the queue depth in
bytes. Using the queue ID as the index, the CE can query every queue
for its used length in unit of packets or bytes.Note that the
QueueStats componennt is defined as optional to implementers.
5.5.2.3. Capabilities
The following capability is currently defined for the
GenericScheduler.
o The queue length limit providing the storage ability for every
queue.
5.5.2.4. Events
This LFB does not have any events specified.
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6. XML for LFB Library
EtherPHYCop
The EtherPHYCop LFB describes an Ethernet interface
which limits the physical media to copper.
1.0
EtherPHYIn
The input port of the EtherPHYCop LFB. It expects any
type of Ethernet frame.
[EthernetAll]
EtherPHYOut
The output port of the EtherPHYCop LFB. The output
packet has the same Ethernet frame type with the
input packet, associated with a metadata indicating
the ID of the physical port.
[EthernetAll]
[PHYPortID]
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PHYPortID
The identification of the physical port
uint32
AdminStatus
The port status administratively requested
PortStatusType
2
OperStatus
The port actual operational status
PortStatusType
AdminLinkSpeed
The port link speed administratively requested
LANSpeedType
LAN_SPEED_AUTO
OperLinkSpeed
The port actual operational link speed
LANSpeedType
AdminDuplexMode
The port duplex mode administratively requested
DuplexType
Auto
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OperDuplexMode
The port actual operational duplex mode
DuplexType
CarrierStatus
The carrier status of the port
boolean
false
SupportedLinkSpeed
A list of link speeds the port supports
LANSpeedType
SupportedDuplexMode
A list of duplex modes the port supports
DuplexType
PHYPortStatusChanged
An event reporting change on operational status of the
physical port.
OperStatus
OperStatus
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LinkSpeedChanged
An event reporting change on operational link speed
of the physical port.
OperLinkSpeed
OperLinkSpeed
DuplexModeChanged
An event reporting change on operational duplex mode
of the physical port.
OperDuplexMode
OperDuplexMode
EtherMACIn
EtherMACIn LFB describes an Ethernet port at MAC data link
layer. The LFB describes Ethernet processing functions
of MAC address locality check, deciding if the Ethernet
packets should be bridged, providing Ethernet layer flow
control, etc.
1.0
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EtherPktsIn
The input port of the EtherMACIn LFB. It expects any
type of Ethernet frame.
[EthernetAll]
[PHYPortID]
NormalPathOut
An output port in the EtherMACIn LFB. It outputs
Ethernet packets to downstream LFBs for normal
processing like Ethernet packet classification and
other L3 IP layer processing.
[EthernetAll]
[PHYPortID]
L2BridgingPathOut
An output port in
the EtherMACIn LFB. It outputs Ethernet packets
to downstream LFBs for layer 2 bridging processing.
The port is switched on or off by the
L2BridgingPathEnable flag in the LFB.
[EthernetAll]
[PHYPortID]
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AdminStatus
The LFB status administratively requested, which has
the same data type with a port status. Default is in
'down' status.
PortStatusType
2
LocalMACAddresses
Local MAC address(es) of the Ethernet port the LFB
represents.
IEEEMAC
L2BridgingPathEnable
A flag indicating if the LFB L2 BridgingPath output
port is enabled or not. Default is not enabled.
boolean
false
PromiscuousMode
A flag indicating whether the LFB is in promiscuous
mode or not. Default is not.
boolean
false
TxFlowControl
A flag indicating whether transmit flow control is
applied or not. Default is not.
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boolean
false
RxFlowControl
A flag indicating whether receive flow control is
applied or not. Default is not.
boolean
false
MACInStats
The statistics of the EtherMACIn LFB
MACInStatsType
EtherClassifier
EtherClassifier LFB describes the process to decapsulate
Ethernet packets and then classify them into various
network layer packets according to information in the
Ethernet headers. It is expected the LFB classifies packets
by packet types like IPv4, IPv6, MPLS, ARP, ND, etc.
1.0
EtherPktsIn
Input port of Ethernet packets. PHYPortID metadata is
always expected while LogicalPortID metadata is
optionally expected to associate with every input
Ethernet packet.
[EthernetAll]
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[PHYPortID]
[
LogicalPortID]
ClassifyOut
A group port for output of Ethernet classifying
results.
[Arbitrary]
[PHYPortID]
[SrcMAC]
[DstMAC]
[EtherType]
[VlanID]
[VlanPriority]
ExceptionOut
A singleton port for output of all Ethernet packets
that fail the classifying process. An ExceptionID
metadata indicates the failure reason.
[Arbitrary]
[ExceptionID]
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EtherDispatchTable
An EtherDispatchTable array component which is defined
in the LFB to dispatch every Ethernet packet to output
ports according to logical port ID assigned by the
VlanInputTable in the LFB and Ethernet type in the
Ethernet packet header.
EtherDispatchTableType
VlanInputTable
A VlanInputTable array component which is defined in
the LFB to classify VLAN Ethernet packets. Every input
packet is assigned with a new LogicalPortID according
to the packet incoming port ID and VLAN ID.
VlanInputTableType
EtherClassifyStats
A table recording statistics on the Ethernet
classifying process in the LFB.
EtherClassifyStatsTableType
EtherEncap
The EtherEncap LFB abstracts the process of encapsulating
Ethernet headers onto received packets. The encapsulation
is based on passed metadata.
1.0
EncapIn
A input port receiving IPv4 and/or IPv6 packets for
encapsulation. A MediaEncapInfoIndex metadata is
expected and a VLAN priority metadata is optionally
expected with every input packet.
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[IPv4]
[IPv6]
[MediaEncapInfoIndex]
[
VlanPriority]
SuccessOut
An output port for packets which have found Ethernet
L2 information and have been successfully encapsulated
into an Ethernet packet. A L2portID metadata is
produced for every output packet.
[IPv4]
[IPv6]
[L2PortID]
ExceptionOut
An output port for packets that fail encapsulation
in the LFB. An ExceptionID metadata indicates failure
reason.
[IPv4]
[IPv6]
[ExceptionID]
[MediaEncapInfoIndex]
[VlanPriority]
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EncapTable
An array table for Ethernet encapsulation information
lookup. Each row of the array contains destination MAC
address, source MAC address, VLAN ID, and output
logical L2 port ID.
EncapTableType
EtherMACOut
EtherMACOut LFB abstracts an Ethernet port at MAC data link
layer. It specifically describes Ethernet packet process
for output to physical port. A downstream LFB is usually an
Ethernet physical LFB like EtherPHYcop LFB. Note that
Ethernet output functions are closely related to Ethernet
input functions, therefore some components defined in this
LFB are as alias of EtherMACIn LFB.
1.0
EtherPktsIn
The input port of the EtherMACOut LFB. It expects any
type of Ethernet frame.
[EthernetAll]
[PHYPortID]
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EtherPktsOut
A port to output all Ethernet packets, each with a
metadata indicating the physical port ID the packet
is to go.
[EthernetAll]
[PHYPortID]
AdminStatus
The LFB status administratively requested, which has
the same data type with a port status. The component
is defined as alias of AdminStatus component in
EtherMACIn LFB.
PortStatusType
MTU
Maximum transmission unit (MTU)
uint32
TxFlowControl
A flag indicating whether transmit flow control is
applied, defined as alias of TxFlowControl component
in EtherMACIn LFB.
boolean
RxFlowControl
A flag indicating whether receive flow control is
applied, defined as alias of RxFlowControl component
in EtherMACIn LFB.
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boolean
MACOutStats
The statistics of the EtherMACOut LFB
MACOutStatsType
IPv4Validator
This LFB performs IPv4 validation according to RFC1812 and
its updates. The IPv4 packet will be output to the
corresponding LFB port, indicating whether the packet is
unicast, multicast or whether an exception has occurred or
the validation failed.
1.0
ValidatePktsIn
Input port for data packets to be validated
[Arbitrary]
IPv4UnicastOut
Output port for validated IPv4 unicast packets
[IPv4Unicast]
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IPv4MulticastOut
Output port for validated IPv4 multicast packets
[IPv4Multicast]
ExceptionOut
Output port for all packets with exceptional cases
when validating. An ExceptionID metadata indicates
the exception case type.
[IPv4]
[ExceptionID]
FailOut
Output port for packets failed validating process.
A ValidateErrorID metadata indicates the error type
or failure reason.
[IPv4]
[ValidateErrorID]
IPv4ValidatorStats
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The statistics information for validating process in
the LFB.
IPv4ValidatorStatsType
IPv6Validator
This LFB performs IPv6 validation according to RFC2460 and
its updates. Then the IPv6 packet will be output to the
corresponding port, indicating whether the packet is a
unicast or a multicast one, an exception has occurred or
the validation failed.
1.0
ValidatePktsIn
Input port for data packets to be validated
[Arbitrary]
IPv6UnicastOut
Output port for validated IPv6 unicast packets
[IPv6Unicast]
IPv6MulticastOut
Output port for validated IPv6 multicast packets
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[IPv6Multicast]
ExceptionOut
Output port for packets with exceptional cases when
validating. An ExceptionID metadata indicates the
exception case type.
[IPv6]
[ExceptionID]
FailOut
Output port for packets failed validating process.
A ValidateErrorID metadata indicates the error type
or failure reason.
[IPv6]
[ValidateErrorID]
IPv6ValidatorStats
The statistics information for validating process in
the LFB.
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IPv6ValidatorStatsType
IPv4UcastLPM
The IPv4UcastLPM LFB abstracts the IPv4 unicast Longest
Prefix Match (LPM) process. This LFB supports to implement
equal-cost multi-path routing (ECMP) and reverse path
forwarding (RPF).
1.0
PktsIn
A port for input of packets to be processed. IPv4
unicast packets are expected.
[IPv4Unicast]
NormalOut
An output port to output IPv4 unicast packets
successfully passed the LPM lookup. A HopSelector
metadata is produced to associate every output packet
for downstream LFB to do next hop action.
[IPv4Unicast]
[HopSelector]
ECMPOut
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The port to output packets needing further ECMP
processing. A downstream ECMP processing LFB is usually
followed to the port. If ECMP is not required, no
downstream LFB may be connected to the port.
[IPv4Unicast]
[HopSelector]
ExceptionOut
The port to output all packets with exceptional cases
happened during LPM process. An ExceptionID metadata
is associated to indicate what caused the exception.
[IPv4Unicast]
[ExceptionID]
IPv4PrefixTable
A table for IPv4 Longest Prefix Match(LPM). The
destination IPv4 address of every input packet is
used as a search key to look up the table to find
out a next hop selector.
IPv4PrefixTableType
IPv4UcastLPMStats
The statistics information for the IPv4 unicast LPM
process in the LFB.
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IPv4UcastLPMStatsType
IPv6UcastLPM
The IPv6UcastLPM LFB abstracts the IPv6 unicast Longest
Prefix Match (LPM) process. This LFB supports to implement
equal-cost multi-path routing (ECMP) and reverse path
forwarding (RPF).
1.0
PktsIn
A port for input of packets to be processed. IPv6
unicast packets are expected.
[IPv6Unicast]
NormalOut
An output port to output IPv6 unicast packets
successfully passed the LPM lookup. A HopSelector
metadata is produced to associate every output packet
for downstream LFB to do next hop action.
[IPv6Unicast]
[HopSelector]
ECMPOut
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The port to output packets needing further ECMP
processing. A downstream ECMP processing LFB is usually
followed to the port. If ECMP is not required, no
downstream LFB may be connected to the port.
[IPv6Unicast]
[HopSelector]
ExceptionOut
The port to output all packets with exceptional cases
happened during LPM process. An ExceptionID metadata
is associated to indicate what caused the exception.
[IPv6Unicast]
[ExceptionID]
IPv6PrefixTable
A table for IPv6 Longest Prefix Match(LPM). The
destination IPv6 address of every input packet is
used as a search key to look up the table to find
out a next hop selector.
IPv6PrefixTableType
IPv6UcastLPMStats
The statistics information for the IPv6 unicast LPM
process in the LFB.
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IPv6UcastLPMStatsType
IPv4NextHop
The IPv4NextHop LFB abstracts the process of next hop
information application to IPv4 packets. It receives an IPv4
packet with an associated next hop identifier (HopSelector),
uses the identifier as a table index to look up a next hop
table to find an appropriate output port. The data
processing also involves the forwarding TTL decrement and
IP checksum recalculation.
1.0
PktsIn
A port for input of unicast IPv4 packets, along with
a HopSelector metadata.
[IPv4Unicast]
[HopSelector]
SuccessOut
The group port for output of packets who successfully
found next hop information. Some metadata are
associated with every packet.
[IPv4Unicast]
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[L3PortID]
[NextHopIPv4Addr]
[
MediaEncapInfoIndex]
ExceptionOut
The output port for packets with exceptional or
failure case. An ExceptionID metadata indicates what
caused the case.
[IPv4Unicast]
[ExceptionID]
IPv4NextHopTable
The IPv4NextHopTable component. A
HopSelector is used to match the table index
to find out a row which contains the next hop
information result.
IPv4NextHopTableType
IPv6NextHop
The LFB abstracts the process of next hop information
application to IPv6 packets. It receives an IPv6 packet
with an associated next hop identifier (HopSelector),
uses the identifier as a table index to look up a next hop
table to find an appropriate output port.
1.0
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PktsIn
A port for input of unicast IPv6 packets, along with
a HopSelector metadata.
[IPv6Unicast]
[HopSelector]
SuccessOut
The group port for output of packets who successfully
found next hop information. Some metadata are
associated with every packet.
[IPv6Unicast]
[L3PortID]
[NextHopIPv6Addr]
[
MediaEncapInfoIndex]
ExceptionOut
The output port for packets with exceptional or
failure case. An ExceptionID metadata indicates what
caused the case.
[IPv6Unicast]
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[ExceptionID]
IPv6NextHopTable
The IPv6NextHopTable component. A HopSelector is used
to match the table index to find out a row which
contains the next hop information result.
IPv6NextHopTableType
RedirectIn
The RedirectIn LFB abstracts the process for the ForCES CE to
inject data packets into the ForCES FE LFBs.
1.0
PktsOut
The output port of RedirectIn LFB, which is defined as
a group port type. From LFB topology point of view,
the RedirectIn LFB acts as a source point for data
packets coming from CE, therefore the LFB is
defined with a singleton output port (and no input
port).
[Arbitrary]
NumPacketsReceived
Number of packets received from CE.
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uint64
RedirectOut
The RedirectOut LFB abstracts the process for LFBs in a
ForCES FE to deliver data packets to the ForCES CE.
1.0
PktsIn
The input port for the RedirectOut LFB. From the LFB's
topology point of view, the RedirectOut LFB acts as a
sink point for data packets going to the CE, therefore
RedirectOut LFB is defined with a singleton input
port (and no output port).
[Arbitrary]
NumPacketsSent
Numble of packets sent to CE.
uint64
BasicMetadataDispatch
The BasicMetadataDispatch LFB is defined to abstract the
process by which packets are dispatched to various output
paths based on associated metadata value. Current version of
the LFB only allows the metadata value be 32-bits integer.
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1.0
PktsIn
The packet input port for dispatching. Every input
packet should be associated with a metadata that will
be used by the LFB to do the dispatch.
[Arbitrary]
[Arbitrary]
PktsOut
The group output port which outputs dispatching
results. A packet with its associated metadata having
found an OutputIndex by successfully looking up the
dispatch table will be output to the group port
instance with the corresponding index.
[Arbitrary]
ExceptionOut
The output port which outputs packets which failed
to process. An ExceptionID metadata indicates what
caused the exception.
[Arbitrary]
[ExceptionID]
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MetadataID
The ID of the metadata to be
used for dispatching packets.
uint32
MetadataDispatchTable
The MetadataDispatchTable component, which contains
entries of a metadata value and an output index,
specifying that a packet with the metadata value must
go out from the instance with the output index of the
LFB group output port.
MetadataDispatchTableType
GenericScheduler
This is a preliminary generic scheduler LFB abstracting
a simple scheduling process, which may be used as a
basic LFB to construct a more complex scheduler LFB.
1.0
PktsIn
The group input port of the LFB. Inside the LFB,
each instance of the group port is connected to
a queue marked with a queue ID, whose value is
index of the port instance.
[Arbitrary]
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PktsOut
The output port of the LFB. Scheduled packets are
output from the port.
[Arbitrary]
SchedulingDiscipline
The SchedulingDiscipline component, which is for the
CE to specify a scheduling discipline to the LFB.
SchdDisciplineType
1
QueueStats
The QueueStats component, which is defined to allow
CE to query every queue statistics in the scheduler.
QueueStatsTableType
QueueLenLimit
The QueueLenLimit capability, which specifies
maximum length of each queue. The length unit is in
bytes.
uint32
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7. LFB Class Use Cases
This section demonstrates examples on how the LFB classes defined by
the Base LFB library in Section 6 can be applied to achieve some
typical router functions. The functions demonstrated are:
o IPv4 forwarding
o ARP processing
It is assumed the LFB topology on the FE described has already been
established by the CE and maps to the use cases illustrated in this
section.
The use cases demonstrated in this section are mere examples and by
no means should be treated as the only way one would construct router
functionality from LFBs; based on the capability of the FE(s), a CE
should be able to express different NE applications.
7.1. IPv4 Forwarding
Figure 2 shows the typical LFB processing path for an IPv4 unicast
forwarding case with Ethernet media interfaces by use of the base LFB
classes. Note that in the figure, to focus on the IP forwarding
function, some inputs or outputs of LFBs that are not related to the
IPv4 forwarding function are not shown. For example, an
EtherClassifier LFB normally has two output ports: a "ClassifyOut"
group output port and a "ExceptionOut" singleton output port, with
the group port contains various port instances according to various
classified packet types(Section 5.1.3). While in this figure, only
the IPv4 and IPv6 packet output port instances are shown for
displaying the mere IPv4 forwarding processing function.
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+-----+ +------+
| | | |
| |<---------------|Ether |<----------------------------+
| | |MACOut| |
| | | | |
|Ether| +------+ |
|PHY | |
|Cop | +---+ |
|#1 | +-----+ | |----->IPv6 Packets |
| | | | | | |
| | |Ether| | | IPv4 Packets |
| |->|MACIn|-->| |-+ +----+ |
+-----+ | | | | | | |---> Multicast Packets |
+-----+ +---+ | | | +-----+ +---+ |
Ether +->| |------->| | | | |
. Classifier| | |Unicast |IPv4 | | | |
. | | |Packets |Ucast|->| |--+ |
. | +----+ |LPM | | | | |
+---+ | IPv4 +-----+ +---+ | |
+-----+ | | | Validator IPv4 | |
| | | | | NextHop| |
+-----+ |Ether| | |-+ IPv4 Packets | |
| |->|MACIn|-->| | | |
| | | | | |----->IPv6 Packets | |
|Ether| +-----+ +---+ | |
|PHY | Ether +----+ | |
|Cop | Classifier | | +-------+ | |
|#n | +------+ | | |Ether | | |
| | | | | |<--|Encap |<-+ |
| | | |<------| | | | |
| |<---------------|Ether | ...| | +-------+ |
| | |MACOut| +---| | |
| | | | | +----+ |
+-----+ +------+ | BasicMetadataDispatch |
+----------->-------------+
Figure 2: LFB use case for IPv4 forwarding
In the LFB use case, a number of EtherPHYCop LFB(Section 5.1.1)
instances are used to describe physical layer functions of the ports.
PHYPortID metadata is generated by EtherPHYCop LFB and is used by all
the subsequent downstream LFBs. An EtherMACIn LFB(Section 5.1.2),
which describe the MAC layer processing, follows every EtherPHYCop
LFB. The EtherMACIn LFB may do a locality check of MAC addresses if
the CE configures the appropriate EtherMACIn LFB component.
Ethernet packets out of the EtherMACIn LFB are sent to an
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EtherClassifier LFB (Section 5.1.3) to be decapsulated and classified
into network layer types like IPv4, IPv6, ARP, etc. In the example
use case, every physical Ethernet interface is associated with one
Classifier instance; although not illustrated, it is also feasible
that all physical interfaces are associated with only one Ethernet
Classifier instance.
EtherClassifier uses the PHYPortID metadata, the Ethernet type of the
input packet, and VlanID (if present in the input Ethernet packets),
to decide the packet network layer type and the LFB output port to
the downstream LFB. The EtherClassifier LFB also assigns a new
logical port ID metadata to the packet for later use. The
EtherClassifier may also generate some new metadata for every packet
like EtherType, SrcMAC, DstMAC, LogicPortID, etc for consumption by
downstream LFBs.
If a packet is classified as an IPv4 packet, it is sent downstream to
an IPv4Validator LFB (Section 5.2.1) to validate the IPv4 packet. In
the validator LFB, IPv4 packets are validated and are additionally
classified into either IPv4 unicast packets or multicast packets.
IPv4 unicast packets are sent to downstream to the IPv4UcastLPM LFB
(Section 5.3.1).
The IPv4UcastLPM LFB is where the longest prefix match decision is
made, and a next hop selection is selected. The next hop ID metadata
is generated by the IPv4UcastLPM LFB to be consumed downstream by the
IPv4NextHop LFB (Section 5.3.2).
The IPv4NextHop LFB uses the next hop ID metadata to do derive where
the packet is to go next and the media encapsulation type for the
port, etc. The IPv4NextHop LFB generates the L3PortID metadata used
to identify a next hop output physical/logical port. In the example
use case, the next hop output port is an Ethernet type; as a result,
the packet and its L3 port ID metadata are sent downstream to an
EtherEncap LFB (Section 5.1.4).
The EtherEncap LFB encapsulates the incoming packet into an Ethernet
frame. A BasicMetadataDispatch LFB (Section 5.5.1) follows the
EtherEncap LFB. The BasicMetadataDispatch LFB is where packets are
finally dispatched to different output physical/logical ports based
on the L3PortID metadata sent to the LFB.
7.2. ARP processing
Figure 3 shows the processing path for ARP protocol in the case the
CE implements the ARP processing function. By no means is this the
only way ARP processing could be achieved; as an example ARP
processing could happen at the FE - but that discussion is out of
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scope for this use case.
+---+ +---+
| | ARP packets | |
| |-------------->---------+--->| | To CE
...-->| | . | | |
| | . | +---+
| | . | RedirectOut
+---+ ^
Ether EtherEncap | IPv4 packets lack
Classifier +---+ | address resolution information
| | |
Packets need | |--------->---+
...--------->| |
L2 Encapsulation| |
+---+ | | +------+
| | +-->| |--+ +---+ |Ether |
| | | +---+ | | |--------->|MACOut|-->...
From CE| |--+ +-->| | . +------+
| |ARP Packets | | .
| |from CE | | . +------+
| | | |--------> |Ether |-->...
+---+ +---+ |MACOut|
RedirectIn BasicMetadata +------+
Dispatch
Figure 3: LFB use case for ARP
There are two ways ARP processing could be triggered in the CE as
illustrated in Figure 3:
o ARP packets arriving from outside of the NE.
o IPV4 packets failing to resolve within the FE.
ARP packets from network interfaces are filtered out by
EtherClassifier LFB. The classified ARP packets and associated
metadata are then sent downstream to the RedirectOut LFB
(Section 5.4.2) to be transported to CE.
The EtherEncap LFB, as described in Section 5.1.4, receives packets
that need Ethernet L2 encapsulating. When the EtherEncap LFB fails
to find the necessary L2 Ethernet information to encapsulate the
packet with, it outputs the packet to its ExceptionOut LFB port.
Downstream to EtherEncap LFB's ExceptionOut LFB port is the
RedirectOut LFB which transports the packet to the CE (Section 5.1.4
on EtherEncap LFB for details).
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To achieve its goal, the CE needs to generate ARP request and
response packets and send them to external (to the NE) networks. ARP
request and response packets from the CE are redirected to an FE via
a RedirectIn LFB (Section 5.4.1).
As was the case with forwarded IPv4 packets, outgoing ARP packets are
also encapsulated to Ethernet format by the EtherEncap LFB, and then
dispatched to different interfaces via a BasicMetadataDispatch LFB.
The BasicMetadataDispatch LFB dispatches the packets according to the
L3PortID metadata included in every ARP packet sent from CE.
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8. Contributors
The authors would like to thank Jamal Hadi Salim, Ligang Dong, and
Fenggen Jia who made major contributions to the development of this
document.
Jamal Hadi Salim
Mojatatu Networks
Ottawa, Ontario
Canada
Email: hadi@mojatatu.com
Ligang Dong
Zhejiang Gongshang University
149 Jiaogong Road
Hangzhou 310035
P.R.China
Phone: +86-571-28877751
EMail: donglg@mail.zjgsu.edu.cn
Fenggen Jia
National Digital Switching Center(NDSC)
Jianxue Road
Zhengzhou 452000
P.R.China
EMail: jfg@mail.ndsc.com.cn
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9. Acknowledgements
This document is based on earlier documents from Joel Halpern, Ligang
Dong, Fenggen Jia and Weiming Wang.
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10. IANA Considerations
IANA has created a registry of ForCES LFB Class Names and the
corresponding ForCES LFB Class Identifiers, with the location of the
definition of the ForCES LFB Class, in accordance with the rules to
use the namespace.
The LFB library in this document needs for unique class names and
numeric class identifiers of all LFBs. Besides, this document also
needs to define the following namespaces:
o Metadata ID, defined in Section 4.3 and Section 4.4
o Exception ID, defined in Section 4.4
o Validate Error ID, defined in Section 4.4
10.1. LFB Class Names and LFB Class Identifiers
LFB classes defined by this document belongs to IETF defined LFBs by
Standard Track RFCs. According to IANA, the identifier namespace for
these LFB classes is from 3 to 65535.
The assignment of LFB class names and LFB class identifiers is as in
the following table.
+-----------+---------------+------------------------+--------------+
| LFB Class | LFB Class Name| Description | Reference |
| Identifier| | | |
+-----------+---------------+------------------------+--------------+
| 3 | EtherPHYCop | Define an Ethernet port| RFC????(this|
| | | abstracted at physical | document) |
| | | layer. | Section 5.1.1|
| | | | |
| 4 | EtherMACIn | Define an Ethernet | RFC???? |
| | | input port at MAC data | Section 5.1.2|
| | | link layer. | |
| | | | |
| 5 |EtherClassifier| Define the process to | RFC???? |
| | | decapsulate Ethernet | Section 5.1.3|
| | | packets and classify | |
| | | the packets. | |
| | | | |
| 6 | EtherEncap | Define the process to | RFC???? |
| | | encapsulate IP packets | Section 5.1.4|
| | | to Ethernet packets. | |
| | | | |
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| 7 | EtherMACOut | Define an Ethernet | RFC ???? |
| | | output port at MAC | Section 5.1.5|
| | | data link layer. | |
| | | | |
| 8 | IPv4Validator | Perform IPv4 packets | RFC ???? |
| | | validation. | Section 5.2.1|
| | | | |
| 9 | IPv6Validator | Perform IPv6 packets | RFC ???? |
| | | validation. | Section 5.2.2|
| | | | |
| 10 | IPv4UcastLPM | Perform IPv4 Longest | RFC ???? |
| | | Prefix Match Lookup. | Section 5.3.1|
| | | | |
| 11 | IPv6UcastLPM | Perform IPv6 Longest | RFC ???? |
| | | Prefix Match Lookup. | Section 5.3.3|
| | | | |
| 12 | IPv4NextHop | Define the process of | RFC ??? |
| | | selecting Ipv4 next hop| Section 5.3.2|
| | | action. | |
| | | | |
| 13 | IPv6NextHop | Define the process of | RFC ??? |
| | | selecting Ipv6 next hop| Section 5.3.4|
| | | action. | |
| | | | |
| 14 | RedirectIn | Define the process for | RFC ??? |
| | | CE to inject data | Section 5.4.1|
| | | packets into FE LFB | |
| | | topology. | |
| | | | |
| 15 | RedirectOut | Define the process for | RFC ??? |
| | | LFBs in FE to deliver | Section 5.4.2|
| | | data packets to CE. | |
| | | | |
| 16 | BasicMetadata | Dispatch input packets | RFC ??? |
| | Dispatch | to a group output | Section 5.5.1|
| | | according to a metadata| |
| | | | |
| 17 | Generic | Define a preliminary | RFC ???? |
| | Scheduler | generic scheduling | Section 5.5.2|
| | | process. | |
+-----------+---------------+------------------------+--------------+
Table 1
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10.2. Metadata ID
The Metadata ID namespace is 32 bits long. The following is the
guideline for managing the namespace.
Metadata ID 0x00000000-0x7FFFFFFF
Metadata with IDs in this range are Specification Required
[RFC5226]. A metadata ID using this range MUST be documented in
an RFC or other permanent and readily available references.
Values assigned by this specification:
+--------------+-------------------------+--------------------------+
| Value | Name | Definition |
+--------------+-------------------------+--------------------------+
| 0x00000001 | PHYPortID | See Section 4.4 |
| 0x00000002 | SrcMAC | See Section 4.4 |
| 0x00000003 | DstMAC | See Section 4.4 |
| 0x00000004 | LogicalPortID | See Section 4.4 |
| 0x00000005 | EtherType | See Section 4.4 |
| 0x00000006 | VlanID | See Section 4.4 |
| 0x00000007 | VlanPriority | See Section 4.4 |
| 0x00000008 | NextHopIPv4Addr | See Section 4.4 |
| 0x00000009 | NextHopIPv6Addr | See Section 4.4 |
| 0x0000000A | HopSelector | See Section 4.4 |
| 0x0000000B | ExceptionID | See Section 4.4 |
| 0x0000000C | ValidateErrorID | See Section 4.4 |
| 0x0000000D | L3PortID | See Section 4.4 |
| 0x0000000E | RedirectIndex | See Section 4.4 |
| 0x0000000F | MediaEncapInfoIndex | See Section 4.4 |
+--------------+-------------------------+--------------------------+
Table 2
Metadata ID 0x80000000-0xFFFFFFFF
Metadata IDs in this range are reserved for vendor private
extensions and are the responsibility of individuals.
10.3. Exception ID
The Exception ID namespace is 32 bits long. The following is the
guideline for managing the namespace.
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Exception ID 0x00000000-0x7FFFFFFF
Exception IDs in this range are Specification Required [RFC5226].
An exception ID using this range MUST be documented in an RFC or
other permanent and readily available references.
Values assigned by this specification:
+--------------+---------------------------------+------------------+
| Value | Name | Definition |
+--------------+---------------------------------+------------------+
| 0x00000000 | AnyUnrecognizedExceptionCase | See Section 4.4 |
| 0x00000001 | ClassifyNoMatching | See Section 4.4 |
| 0x00000002 | MediaEncapInfoIndexInvalid | See Section 4.4 |
| 0x00000003 | EncapTableLookupFailed | See Section 4.4 |
| 0x00000004 | BadTTL | See Section 4.4 |
| 0x00000005 | IPv4HeaderLengthMismatch | See Section 4.4 |
| 0x00000006 | RouterAlertOptions | See Section 4.4 |
| 0x00000007 | IPv6HopLimitZero | See Section 4.4 |
| 0x00000008 | IPv6NextHeaderHBH | See Section 4.4 |
| 0x00000009 | SrcAddressExecption | See Section 4.4 |
| 0x0000000A | DstAddressExecption | See Section 4.4 |
| 0x0000000B | LPMLookupFailed | See Section 4.4 |
| 0x0000000C | HopSelectorInvalid | See Section 4.4 |
| 0x0000000D | NextHopLookupFailed | See Section 4.4 |
| 0x0000000E | FragRequired | See Section 4.4 |
| 0x0000000F | MetadataNoMatching | See Section 4.4 |
+--------------+---------------------------------+------------------+
Table 3
Exception ID 0x80000000-0xFFFFFFFF
Exception IDs in this range are reserved for vendor private
extensions and are the responsibility of individuals.
10.4. Validate Error ID
The Validate Error ID namespace is 32 bits long. The following is
the guideline for managing the namespace.
Validate Error ID 0x00000000-0x7FFFFFFF
Validate Error IDs in this range are Specification Required
[RFC5226]. A Validate Error ID using this range MUST be
documented in an RFC or other permanent and readily available
references.
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Values assigned by this specification:
+--------------+---------------------------------+------------------+
| Value | Name | Definition |
+--------------+---------------------------------+------------------+
| 0x00000000 | AnyUnrecognizedValidateErrorCase| See Section 4.4 |
| 0x00000001 | InvalidIPv4PacketSize | See Section 4.4 |
| 0x00000002 | NotIPv4Packet | See Section 4.4 |
| 0x00000003 | InvalidIPv4HeaderLengthSize | See Section 4.4 |
| 0x00000004 | InvalidIPv4LengthFieldSize | See Section 4.4 |
| 0x00000005 | InvalidIPv4Checksum | See Section 4.4 |
| 0x00000006 | InvalidIPv4SrcAddr | See Section 4.4 |
| 0x00000007 | InvalidIPv4DstAddr | See Section 4.4 |
| 0x00000008 | InvalidIPv6PakcetSize | See Section 4.4 |
| 0x00000009 | NotIPv6Packet | See Section 4.4 |
| 0x0000000A | InvalidIPv6SrcAddr | See Section 4.4 |
| 0x0000000B | InvalidIPv6DstAddr | See Section 4.4 |
+--------------+---------------------------------+------------------+
Table 4
Validate Error ID 0x80000000-0xFFFFFFFF
Validate Error IDs in this range are reserved for vendor private
extensions and are the responsibility of individuals.
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11. Security Considerations
The ForCES framework document [RFC3746] provides a comprehensive
security analysis for the overall ForCES architecture. For example,
the ForCES protocol entities must be authenticated per the ForCES
requirements before they can access the information elements
described in this document via ForCES. Access to the information
contained in this document is accomplished via the ForCES
protocol[RFC5810], which is defined in separate documents, and thus
the security issues will be addressed there.
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12. References
12.1. Normative References
[RFC5810] Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang,
W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and
Control Element Separation (ForCES) Protocol
Specification", RFC 5810, March 2010.
[RFC5812] Halpern, J. and J. Hadi Salim, "Forwarding and Control
Element Separation (ForCES) Forwarding Element Model",
RFC 5812, March 2010.
12.2. Informative References
[RFC1122] Braden, R., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, October 1989.
[RFC1812] Baker, F., "Requirements for IP Version 4 Routers",
RFC 1812, June 1995.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Structure of Management Information
Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
July 2003.
[RFC3654] Khosravi, H. and T. Anderson, "Requirements for Separation
of IP Control and Forwarding", RFC 3654, November 2003.
[RFC3746] Yang, L., Dantu, R., Anderson, T., and R. Gopal,
"Forwarding and Control Element Separation (ForCES)
Framework", RFC 3746, April 2004.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
Wang, et al. Expires August 1, 2013 [Page 113]
Internet-Draft ForCES LFB Library January 2013
Authors' Addresses
Weiming Wang
Zhejiang Gongshang University
18 Xuezheng Str., Xiasha University Town
Hangzhou, 310018
P.R.China
Phone: +86 571 28877721
Email: wmwang@zjsu.edu.cn
Evangelos Haleplidis
University of Patras
Patras,
Greece
Email: ehalep@ece.upatras.gr
Kentaro Ogawa
NTT Corporation
Tokyo,
Japan
Email: ogawa.kentaro@lab.ntt.co.jp
Chuanhuang Li
Hangzhou H3C Tech. Co., Ltd.
310 Liuhe Road, Zhijiang Science Park
Hangzhou, 310053
P.R.China
Phone: +86 571 86760000
Email: chuanhuang_li@zjsu.edu.cn
Halpern Joel
Ericsson
P.O. Box 6049
Leesburg, 20178
VA
Phone: +1 703 371 3043
Email: joel.halpern@ericsson.com
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