Internet DRAFT - draft-wang-lsr-ifit-node-capability-advertisement
draft-wang-lsr-ifit-node-capability-advertisement
Link State Routing Working Group Y. Wang
Internet-Draft T. Zhou
Intended status: Standards Track M. Liu
Expires: September 24, 2020 Huawei
R. Pang
China Unicom
March 23, 2020
In-situ Flow Information Telemetry (IFIT) Node Capability Advertisement
draft-wang-lsr-ifit-node-capability-advertisement-00
Abstract
For advertising In-situ Flow Information Telemetry (IFIT) node
capabilities within the entire routing domain, this document extends
a new optional TLV to the OSPF RI Opaque LSA, a new optional sub-TLV
to the IS-IS Router CAPABILITY TLV, and a new Node Attribute TLV that
is encoded in the BGP-LS attribute with Node NLRIs to carry IFIT node
capabilities information. Such advertisement allows entities (e.g. a
centralized controller) to determine whether a particular IFIT
functionality can be supported in a given network.
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 RFC 2119 [RFC2119].
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
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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 September 24, 2020.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IFIT Node Capability Advertisement . . . . . . . . . . . . . 3
3.1. IFIT Node Capability Information . . . . . . . . . . . . 3
3.2. OSPF Extension IFIT Node Capability TLV . . . . . . . . . 5
3.3. IS-IS Extension IFIT Node Capability Sub-TLV . . . . . . 6
3.4. BGP-LS Extension IFIT Node Capability TLV . . . . . . . . 6
4. Application . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
IFIT provides a complete framework architecture and a reflection-loop
working solution for on-path flow telemetry
[I-D.song-opsawg-ifit-framework]. At present, there are a family of
emerging on-path flow telemetry techniques, including In-situ OAM
(IOAM) [I-D.ietf-ippm-ioam-data], Postcard-Based Telemetry (PBT)
[I-D.song-ippm-postcard-based-telemetry], IOAM Direct Export (DEX)
[I-D.ioamteam-ippm-ioam-direct-export], Enhanced Alternate Marking
(EAM) [I-D.zhou-ippm-enhanced-alternate-marking], etc. IFIT is a
solution focusing on network domains. The "network domain" consists
of a set of network devices or entities within a single Atonomous
System (AS). The part of the network which employs IFIT is referred
to as the IFIT domain. One network domain may consist of multiple
IFIT domains. An IFIT domain may cross multiple network domains.
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The family of emerging on-path flow telemetry techniques may be
selectively or partially enabled in different vendors' devices as an
emerging feature for various use cases of application-aware network
operations. So that in order to dynamically enable IFIT
functionality in a network domain, it is necessary to advertise the
information of IFIT option types supported in each device.
BGP-LS defines a way to advertise topology and associated attributes
and capabilities of the nodes in that topology to a centralized
controller [RFC7752]. Typically, BGP-LS is configured on a small
number of nodes that do not necessarily act as head-ends. In order
for BGP-LS to signal IFIT node capabilities for all the devices in
the network, IFIT node capabilities SHOULD be advertised by every IGP
router in the network. Therefore, this document defines extensions
to OSPF, IS-IS, and BGP-LS to advertise the IFIT node capabilities.
Entities (e.g. centralized controllers) that can use this information
to determine whether a particular IFIT functionality can be enabled
in a given IFIT domain. An application to this information
advertisement is described in detail in Section 4.
2. Terminology
OSPF: Open Shortest Path First
IS-IS: Intermediate System to Intermediate System
RI: Router Information
LSA: Link State Advertisement
BGP-LS: Advertisement of Link-State and TE Information using Border
Gateway Protocol
3. IFIT Node Capability Advertisement
3.1. IFIT Node Capability Information
Each IFIT node is configured with a node-id which uniquely identifies
a node within the associated IFIT domain. To accommodate the
different use cases or requirements of in-situ flow information
telemetry, IFIT data fields updated by network nodes fall into
different categories which are referred as different IFIT option
types, including IOAM Trace Option-Types [I-D.ietf-ippm-ioam-data],
IOAM Edge-to-Edge (E2E) Option-Type [I-D.ietf-ippm-ioam-data], IOAM
DEX Option-Type [I-D.ioamteam-ippm-ioam-direct-export] and Enhanced
Alternate Marking (EAM) Option-Type
[I-D.zhou-ippm-enhanced-alternate-marking]. And a subset or all the
IFIT-Option-Types and their corresponding IFIT-Data-Fields can be
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associated to an IFIT-Namespce. The Namespace identifiers allow
devices which are IFIT capable to determine whether IFIT-Option-Types
need to be processed. So that IFIT-Option-Types and Namespace-ID
SHOULD be carried in IFIT node capability information for
advertisement.
In this document, the IFIT-Node-Capability information consists of
one or more pairs of a 2-octet Namespace-ID and 16-bit Option-Type
enabled Flag.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------------------------------------------------------+
| Namespace-ID_1 | Option-Type enabled Flag_1 |
+---------------------------------------------------------------+
| Namespace-ID_2 | Option-Type enabled Flag_2 |
+---------------------------------------------------------------+
| ... | ... |
+---------------------------------------------------------------+
Fig. 4 IFIT-Node-Capability Format
Where:
Namespace-ID: A 16-bit identifier, which MUST be present and
populated in all IFIT-Option-Types. The definition is the same as
described in [I-D.ietf-ippm-ioam-data].
Option-Type enabled Flag: A 16-bit field, which is defined as:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-------------------------------+
|p|i|d|e|m| Reserved |
+-------------------------------+
Where:
p-Flag: IOAM Pre-allocated Trace Option Type-enabled flag. If bit p
is set (1), the router is capable of IOAM Pre-allocated Trace
[I-D.ietf-ippm-ioam-data].
i-Flag: IOAM Incremental Trace Option Type-enabled flag. If bit i is
set (1), the router is capable of IOAM Incremental Tracing
[I-D.ietf-ippm-ioam-data].
d-Flag: IOAM DEX Option Type-enabled flag. If bit d is set (1), the
router is capable of IOAM DEX [I-D.ioamteam-ippm-ioam-direct-export].
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e-Flag: IOAM E2E Option Type-enabled flag. If bit e is set (1), the
router is capable of IOAM E2E processing [I-D.ietf-ippm-ioam-data].
m-Flag: Enhanced Alternative Marking enabled flag. If bit m is set
(1), then the router is capable of processing Enhanced Alternative
Marking packets [I-D.zhou-ippm-enhanced-alternate-marking].
Reserved: Must be set to zero upon transmission and ignored upon
receipt.
An IFIT node SHALL be capable of more than one IFIT option types. So
in this case, Option-Type enabled Flag can has more than one bit
being set.
3.2. OSPF Extension IFIT Node Capability TLV
Given that OSPF uses the options field in LSAs and hello packets to
advertise optional router capabilities [RFC7770], this document
defnes a new IFIT Node Capability TLV within the body of the OSPF RI
Opaque LSA [RFC7770] to carry the IFIT node capabilities of the
router originating the RI LSA. The IFIT Node Capability TLV is
composed of three fields, a 2-octet Type field, a 2-octet Length
field, and 4-octet Value field. The Type field indicates the type of
items in the Value field. The Length field indicates the length of
the Value field in octets. The Value field carries the IFIT Node
Capability information, which is a multiple of 4 octets field.
The IFIT node capability TLV has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| Type | Length |
+---------------------------------------------------------------+
| IFIT-Node-Capability |
~ ~
+---------------------------------------------------------------+
Fig. 1 OSPF IFIT Node Capability TLV Format
Type: To be assigned by IANA
Length: A 2-octet field that indicates the length of the value field.
IFIT-Node-Capability: A multiple of 4 octets field, which is as
defined in Section 3.1.
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3.3. IS-IS Extension IFIT Node Capability Sub-TLV
The IS-IS Extensions for Advertising Router Information TLV named IS-
IS Router CAPABILITY TLV [RFC7981], which allows a router to announce
its capabilities within an IS-IS level or the entire routing domain,
has been chosen for IFIT node capabilities advertisement. IS-IS
Router CAPABILITY TLV is formed of multiple sub-TLVs [RFC5305].
According to the format of IS-IS Router CAPABILITY TLV [RFC7981], the
IFIT Node Capability sub-TLV is composed of three fields, a one-octet
Type field, a one-octet Length field, and zero or more octets of
Value. The Type field indicates the type of items in the Value
field. The Length field indicates the length of the Value field in
octets. The Value field indicates the IFIT Node Capability, which is
a multiple of 4 octets field.
The IS-IS IFIT Node-capability Sub-TLV has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------+---------------+
| Type | Length |
+---------------+---------------+-------------------------------+
| IFIT-Node-Capability |
~ ~
+---------------------------------------------------------------+
Fig. 2 IS-IS IFIT Node Capability Sub-TLV Format
Type: To be assigned by IANA
Length: A 8-bit field that indicates the length of the value portion
in octets.
IFIT-Node-Capability: A multiple of 4 octets field, which is as
defined in Section 3.1.
3.4. BGP-LS Extension IFIT Node Capability TLV
This document describes extensions enabling BGP-LS speakers to
announce the IFIT node capabilities of routers in a network to a BGP-
LS consumer (e.g. a centralized controller). The centralized
controller can leverage this information in enabling IFIT
applications in network domains based on IFIT node capabilities and
OAM use cases.
IFIT Node-Capability TLV is defined as a new Node Attribute TLV that
is encoded in the BGP-LS attribute with Node NLRIs [RFC7752]. The
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IFIT Node Capability TLV is defined as a TLV triplet, i.e. a 2-octet
Type field, a 2-octet Length field, and 4-octet Value field. The
Type field indicates the type of items in the Value field. The
Length field indicates the length of the Value field in octets. The
Value field indicates the IFIT Node Capability, which is a multiple
of 4 octets field.
The BGP-LS IFIT Node Capability TLV has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| Type | Length |
+---------------------------------------------------------------+
| IFIT-Node-Capability |
~ ~
+---------------------------------------------------------------+
Fig. 3 BGP-LS IFIT Node Capability TLV Format
Type: To be assigned by IANA
Length: A 2-octet field that indicates the length of the value.
IFIT-Node-Capability: A multiple of 4 octets field, which is as
defined in Section 3.1.
4. Application
Within an IFIT domain, one or more IFIT-Option-Types are added into
packets at the IFIT-capable head node that is referred to as the IFIT
encapsulating node. Then IFIT-Data-Fields may be updated by IFIT
transit nodes that the packet traverses. Finally, IFIT-Option-Types
are removed at the IFIT-capable end node that is referred to as the
IFIT decapsulating node. The role of an IFIT-encapsulating, IFIT-
transit or IFIT-decapsulating node is always performed within a
specific Namespce.
As any packet with IFIT-specific header and metadata MUST not leak
out from the IFIT domain, the IFIT decapsulating node MUST be able to
capture packets with IFIT-specific header and metadata and recover
their format before forwarding them out of the IFIT domain. So that
entities (e.g., centralized controllers) can use IFIT node
capabilities information to avoid the leak of IFIT-specific header
and metadata.
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Besides, in order to adapt to different network conditions and
different application requirements, a centralized controller needs to
switch between different underlying techniques. As different IFIT
option types have different encapsulation format in packets and have
different processing procedure when packets travers to encapsulating,
transit, and decapsulating nodes. For example, for IOAM Trace
Option-Types, IOAM tracing data is expected to be collected at every
IOAM transit node that a packet traverses to ensure visibility into
the entire path a packet takes within an IOAM-domain. If not all
nodes within a domain are IOAM Trace Option-Type capable, IOAM-Data-
Fields will only be changed on those nodes which are IOAM Trace
Option-Type capable and IOAM tracing information will only be
collected by those IOAM-capable nodes. For IOAM DEX Option-Type, the
requred IOAM data is expected to be exported at every transit node
that process a packet with the DEX option.
Therefore, this advertisement allows entities (e.g., centralized
controllers) to determine whether a specific IFIT functionality can
be supported by all devices in a network domain, then enable the
IFIT-Data-Fields encapsulation at the head node.
5. IANA Considerations
This document makes the following registrations for a TLV type of the
new IFIT Node Capability TLV within the body of the OSPF RI Opaque
LSA, a Sub-TLV type of the new Sub-TLV proposed from the "Sub-TLVs
for TLV 242 (IS-IS Router CAPABILITY TLV)" registry, and a BGP-LS
Node Attribute TLV code point for the IFIT Node Capability TLV.
+------+-----------------------------------------+
| Type | Description |
+------+-----------------------------------------+
| TBD | OSPF Extension IFIT Node Capability TLV |
+------+-----------------------------------------+
+------+----------------------------------------------+
| Type | Description |
+------+----------------------------------------------+
| TBD | IS-IS Extension IFIT Node Capability Sub-TLV |
+------+----------------------------------------------+
+------------+-------------------------------------------+
| Code Point | Description |
+------------+-------------------------------------------+
| TBD | BGP-LS Extension IFIT Node Capability TLV |
+------------+-------------------------------------------+
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6. Security Considerations
This document introduces a new TLV within the existing OSPF RI Opaque
LSA, a new sub-TLV for the existing IS-IS Router capability TLV, and
a new Node Attribute TLV for the existing Node NLRIs. It does not
introduce any new security risks to OSPF, IS-IS and BGP-LS.
7. Acknowledgements
TBD.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5305] "IS-IS Extensions for Traffic Engineering",
<https://www.rfc-editor.org/info/rfc5305>.
[RFC7752] "North-Bound Distribution of Link-State and Traffic
Engineering (TE) Information Using BGP",
<https://datatracker.ietf.org/doc/rfc7752/>.
[RFC7770] "Extensions to OSPF for Advertising Optional Router
Capabilities", <https://www.rfc-editor.org/info/rfc7770>.
[RFC7981] "IS-IS Extensions for Advertising Router Information",
<https://www.rfc-editor.org/info/rfc7981>.
8.2. Informative References
[I-D.ietf-ippm-ioam-data]
"Data Fields for In-situ OAM".
[I-D.ioamteam-ippm-ioam-direct-export]
"In-situ OAM Direct Exporting",
<https://datatracker.ietf.org/doc/draft-ioamteam-ippm-
ioam-direct-export/>.
[I-D.song-ippm-postcard-based-telemetry]
"Postcard-based On-Path Flow Data Telemetry",
<https://datatracker.ietf.org/doc/draft-song-ippm-
postcard-based-telemetry/>.
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[I-D.song-opsawg-ifit-framework]
"In-situ Flow Information Telemetry Framework",
<https://datatracker.ietf.org/doc/draft-song-opsawg-ifit-
framework/>.
[I-D.zhou-ippm-enhanced-alternate-marking]
"Enhanced Alternate Marking Method",
<https://datatracker.ietf.org/doc/draft-zhou-ippm-
enhanced-alternate-marking/>.
Authors' Addresses
Yali Wang
Huawei
156 Beiqing Rd., Haidian District
Beijing
China
Email: wangyali11@huawei.com
Tianran Zhou
Huawei
156 Beiqing Rd., Haidian District
Beijing
China
Email: zhoutianran@huawei.com
Min Liu
Huawei
156 Beiqing Rd., Haidian District
Beijing
China
Email: lucy.liumin@huawei.com
Ran Pang
China Unicom
9 Shouti South Rd., Haidian District
Beijing
China
Email: pangran@chinaunicom.cn
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