Internet DRAFT - draft-li-isis-mpls-multi-topology
draft-li-isis-mpls-multi-topology
Network Working Group Z. Li
Internet-Draft Q. Zhao
Intended status: Standards Track Huawei Technologies
Expires: April 24, 2014 October 21, 2013
IS-IS Extensions for MPLS Multi-Topology
draft-li-isis-mpls-multi-topology-00
Abstract
MPLS plays a key role in the process of implementing network
virtualization. [I-D.li-mpls-network-virtualization-framework]
proposes the framework to implement MPLS virtual network basedn on
the architecture of central controller IGP. This document defines
the corresponding IS-IS protocol extension and procedures to support
MPLS Multi-Topology.
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
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This Internet-Draft will expire on April 24, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Application for MRT FRR . . . . . . . . . . . . . . . . . 3
4. IS-IS Extensions . . . . . . . . . . . . . . . . . . . . . . 4
4.1. IS-IS Label Mapping TLV . . . . . . . . . . . . . . . . . 4
4.2. Label Sub-TLV . . . . . . . . . . . . . . . . . . . . . . 5
4.3. MPLS Multi-Topology Sub-TLV . . . . . . . . . . . . . . . 6
4.4. Procedures . . . . . . . . . . . . . . . . . . . . . . . 6
5. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
As the virtual network operators develop, it is desirable to provide
better network virtualization solutions to facilitate the service
provision. [I-D.li-mpls-network-virtualization-framework] proposes a
new framework to implement MPLS virtual network based on the
architecture of central controlled IGP. It is to allocate MPLS
global label for the virtual network topologies, network nodes and
links by an IGP controller to IGP clients. Thus MPLS global labels
becomes the unique identifications in the underlying networks to
compose the virtual networks.
This document defines the corresponding IS-IS protocol extensions and
procedures to support MPLS virtual network topology. The other
document will define the corresponding IS-IS protocol extensions and
procedures to support MPLS virtualized network nodes and links.
2. Terminology
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Underlying Network: It is the network which the virtual network is
built based on. The underlying network can be the physical network
or the virtual network.
MPLS Virtual Network: The virtual network is built based on the
underlying network. It is composed by virtual nodes and virtual
links which are identified by MPLS global label. In this document,
the concept of virtual network is the same as that of MPLS virtual
network.
MPLS Virtual Network Topology: It is the topology of the MPLS virtual
network. It can be identified multi-topology ID of corresponding
virtual network. MPLS global label is allocated to represent the
virtual network topology.
3. Overview
[I-D.li-rtgwg-cc-igp-arch] defines the central controlled
architecture for IGP. In
[I-D.li-mpls-network-virtualization-framework], a new framework is
defined to implement MPLS virtual network based on central controlled
IGP. In the MPLS virtual network, the virtual network topology can
be identified by the Multi-Topology ID. The global label for the
virtual network topology is allocated by the IGP controller and the
label binding between the Multi-Topology ID and the Global Label are
flooded from the IGP controller to IGP clients. When IGP clients
receives the label binding, it can install the MPLS forwarding entry
to map the incoming label to the forwarding instance corresponding to
the Multi-Topology.
3.1. Application for MRT FRR
MRT FRR [I-D.ietf-rtgwg-mrt-frr-architecture] has been proposed to
provide 100% coverage of FRR deployment in the network. There are
two forwarding mechanisms defined in : IP tunnel forwarding mechanism
and LDP Multi-Topology mechanism. IP tunnel forwarding mechanism
need to set up IP tunnels which must introduce extra IP addresses.
It is difficult to satisfy the scalability requirement for
deployment. LDP Multi-Topology is a scalable way to implement the
MRT FRR forwarding. But for the pure IP network it has to introduce
the new MPLS protocol. Moreover, it may use more labels which are
allocated for prefixes in three topologies: the default topology, the
blue topology and the red topology.
When the MPLS virtual network mechanism is introduced, the MRT FRR
forwarding in the IP network can be simplified greatly. Two MPLS
global label can be allocated to identify the blue topology and the
red topology. According to MRT calculation, the forwarding instances
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for the default topology, the red topology and the blue topology can
be installed. For a specific IP prefix, the forwarding entry will
consist of the primary path in the default topology and the secondary
path in the red topology or the blue topology. IP packets will
forward hop by hop according to the FIB of the default topology.
When failure happens, they will be forwarded in the blue topology or
the red topology which contains the secondary path. When forwarding,
the global label for the Multi-Topology is encapsulated for the IP
packets. When the next hop node receives the packets, it will
decapsulate the label and map to the corresponding forwarding
instance of the red topology or the blue topology according to the
MPLS forwarding entry. When determine the outgoing interface and the
next hop after looking up the Multi-Topology FIB according to the
destination IP address, the packet will encapsulate the global label
again which represent the red topology or the blue topology and will
be forwarded to the next hop. This forwarding process will be done
by each node until it reaches the destination.
In the MRT FRR process, there are only two MPLS forwarding entries to
map the label to the red topology and the blue topology. Moreover,
it is done by IGP extensions instead of introducing LDP, which can
also simplify the network operation and management.
4. IS-IS Extensions
4.1. IS-IS Label Mapping TLV
A new IS-IS TLV, call as Label Mapping TLV, is introduced to allocate
MPLS label. The IS-IS Label Mapping TLV format is shown in the
following figure. The type of IS-IS Label Mapping TLV is to be
defined by IANA. The flags in the TLV are to be defined. There are
a series of sub-TLV in the TLV which length can be up to 252 octets.
There MUST be at least one Label Sub-TLV and one FEC sub-TLV in the
TLV. The Label sub-TLV contains the label value allocated. The FEC
sub-TLV contains the Forwarding Equivalent Class for which the label
is allocated. In this document, one FEC sub-TLV is defined, called
as MPLS Multi-Topology sub-TLV.
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 | Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Sub-TLV |
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| FEC Sub-TLV |
. .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: IS-IS Label Mapping TLV format
4.2. Label Sub-TLV
As defined in [I-D.li-mpls-global-label-framework], there are two
types of methods to allocated global label: the first one is to use
the existing MPLS label range, that is, from 16 to 2^20; the second
one is to use the expanded MPLS label range which can be more than
2^20. Taking into account the future expansion, the Label Sub-TLV
has 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label (24 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
......
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label (24 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Label Sub-TLV Format
o Type: 1 octet of sub-TLV type. It is to be allocated by IANA.
o Length: 1 octet of length of the value field of the sub-TLV. It
can be up to 252 octets.
o MPLS Label Field: variable length. It consists of one or more
labels. Each label is encoded as 3 octets, where the high-order 20
bits contain the label value, and the low order bit contains "Bottom
of Stack".
The label stack in the Label sub-TLV can construct a big label range
which can exceed 2^20. If there is only one label field, it is
consistent with the existing MPLS label range from 16 to 2^20.
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4.3. MPLS Multi-Topology Sub-TLV
When implement virtual topology, the global label is allocated for
the Multi-topology ID. MPLS Multi-Topology ID can be seen as the FEC
for the label mapping. The MPLS Multi-Topology sub-TLV format has
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Multi-Topology ID (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Multi-Topology Sub- TLV format
o Type: 1 octet of sub-TLV type. It is to be allocated by IANA.
o Length: 1 octet of length of the value field of the sub-TLV. It is
4.
o Multi-Topology ID: 4 octets. It contains the MPLS Multi-Topology
ID for which the global label is allocated to implement virtual
topology.
4.4. Procedures
When the IGP controller needs to implement the MPLS virtual network
topology, the IGP controller MUST originate a new LSP comprising the
Label Mapping TLV for the MPLS virtual network topology. The Label
Mapping TLV MUST contain one or more pairs of the Label sub-TLV and
the Multi-Topology ID sub-TLV. If the length of these sub-TLVs can
exceeds 252 octets, there SHOULD be multiple Label Mapping TLVs in
IS-IS LSP.
When receiving the Label Mapping to implement the virtual network
topology, the IGP clients SHOULD get the global label and the
corresponding multi-topology from the sub-TLVs in the label mapping
TLV and install MPLS fowarding entry accordingly.
5. Compatibility
Routers that do not support these MPLS Virtualization extensions
SHOULD silently ignore the TLV and the sub-TLVs defined in this
document.
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6. IANA Considerations
This document request to allocate a type value for the Label Mapping
TLV, a type value for the Label sub-TLV and a type value for the MPLS
Multi-Topology sub-TLV.
7. Security Considerations
TBD.
8. References
8.1. Normative References
[I-D.li-mpls-global-label-framework]
Li, Z., Zhao, Q., and T. Yang, "A Framework of MPLS Global
Label", draft-li-mpls-global-label-framework-00 (work in
progress), July 2013.
[I-D.li-mpls-network-virtualization-framework]
Li, Z. and M. Li, "Framework of Network Virtualization
Based on MPLS Global Label", draft-li-mpls-network-
virtualization-framework-00 (work in progress), October
2013.
[I-D.li-rtgwg-cc-igp-arch]
Li, Z., Chen, H., and G. Yan, "An Architecture of Central
Controlled Interior Gateway Protocol (IGP)", draft-li-
rtgwg-cc-igp-arch-00 (work in progress), October 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
8.2. Informative References
[I-D.gredler-isis-label-advertisement]
Gredler, H., Amante, S., Scholl, T., and L. Jalil,
"Advertising MPLS labels in IS-IS", draft-gredler-isis-
label-advertisement-03 (work in progress), May 2013.
[I-D.ietf-rtgwg-mrt-frr-architecture]
Atlas, A., Kebler, R., Envedi, G., Csaszar, A., Tantsura,
J., Konstantynowicz, M., and R. White, "An Architecture
for IP/LDP Fast-Reroute Using Maximally Redundant Trees",
draft-ietf-rtgwg-mrt-frr-architecture-03 (work in
progress), July 2013.
[I-D.previdi-isis-segment-routing-extensions]
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Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., and
S. Litkowski, "IS-IS Extensions for Segment Routing",
draft-previdi-isis-segment-routing-extensions-02 (work in
progress), July 2013.
Authors' Addresses
Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
Quintin Zhao
Huawei Technologies
Boston, MA
USA
Email: quintin.zhao@huawei.com
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