Internet DRAFT - draft-chen-spring-segemt-routing-anycast-frr
draft-chen-spring-segemt-routing-anycast-frr
Networking Working Group Ran. Chen
Internet-Draft Shaofu. Peng
Intended status: Standards Track ZTE Corporation
Expires: June 8, 2018 December 05, 2017
Anycast-SID FRR for Segment Routing Network
draft-chen-spring-segemt-routing-anycast-frr-00
Abstract
This document specifies the fast redundancy protection mechanism,
aimed at providing protection of the domain boundary nodes in Cross
domain scenario.
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This Internet-Draft will expire on June 8, 2018.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 2
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 2
4. Anycast-SID FRR Solution . . . . . . . . . . . . . . . . . . 2
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. Normative references . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
This document specifies the fast redundancy protection mechanism,
aimed at providing protection of the domain boundary nodes in Cross
domain scenario.
2. Conventions used in this document
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.
3. Motivation
The procedures specified in this document, in combination with
[I-D.ietf-spring-segment-routing] provide the fast redundancy
protection.
The procedures specified in this document aims at providing
protection of the domain boundary nodes in Cross domain scenario.
4. Anycast-SID FRR Solution
The solution consists of three parts.
o Configure the same anycast prefix and associated prefix-sid for
each domain boundary node that forms redundant protection, then
the anycast prefix and associated prefix-sid with Anycast-Group
flag should be advertised to the neighbor node.
o Create the anycast-group forwarding entry (i.e. FRR entry) after
the direct neighbor node of the domain boundary nodes receive the
prefix-sid with Anycast-Group flag advertisement. The anycast-
group forwarding entry includes the forwarding information which
points to each of the domain boundary node , then the forwarding
entry pointing to the main domain boundary (one of the direct
connected boundary nodes from the PLR) is set to the active state,
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and others are set to the backup state. Only the direct neighbor
of the domain boundary nodes need to set up the anycast-group
forwarding entry.
o if the neighbor node detects the main domain boundary node
failure, the neighbor node immediately activates the backup entry.
Note that the backup entry contains the node-sid of the slave
boundary node, and the packet will be forwarded based on the node-
sid, not the anycast prefix-sid again.
+-----------------------+ +---------------+ +------------------+
| SID:20 SID:30 | | | | SID:60 |
| A2-----A3------GW11------C1------GW21------A6 |
| / \ / | |\ / \ /| | \ |
| / \ / | | \ / \ / | | \ |
|SID:10/ \ / | | \ / \ / | | \ SID:80 |
| A1 / SID:100 / / SID:200 A8 |
| \ / \ | | / \ / \ | | / |
| \ / \ | | / \ / \ | | / |
| \ / \ | |/ \ / \| | / |
| A4-----A5------GW12------C2------GW22-------A7 |
| SID:40 SID:50 | | | | SID:70 |
+-----------------------+ +---------------+ +------------------+
Figure 1
The figure above describes a network example with two groups of the
domain boundary nodes. The GW11 and GW12 are in the same anycast
group. They are all configured with the same anycast prefix and the
same prefix-sid 100, in addition, GW11 has node-sid 110 and GW12 has
node-sid 120. All these prefix-sid should be advertised to the
Neighbors(e.g, node A3 and A5), and the anycast-group forwarding
entry will be set up by the direct Neighbor node A3 and A5. For
example, the anycast-group forwarding entry created by A3 contains a
master item which points to anycast-sid 100 and a slave item which
points to node-sid 120.
When A3 detects GW11 failure, it immediately diverting traffic from
GW11 to A4 (e.g. the best next-hop to node-sid 120) according to the
anycast-group forwarding entry.
It is an implementation choice for data-plane whether the slave item
only points to node-sid 120 for cascade table lookup, or integrates
the forwarding information of node-sid 120 (such as a single next-
hop, a TI-LFA FRR index for cascade table lookup, or an ECMP index
for cascade table lookup).
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Note that the anycast-group FRR described in this document could co-
exist with other FRR solutions, such as LFA/RLFA/TI-LFA. The
anycast-group FRR solution needn't complex alternate path
computation, it just reuses the forwarding information which points
to the slave boundary node.
5. Security Considerations
TBD.
6. Acknowledgements
TBD.
7. Normative references
[I-D.ietf-isis-segment-routing-extensions]
Previdi, S., Filsfils, C., Bashandy, A., Gredler, H.,
Litkowski, S., Decraene, B., and J. Tantsura, "IS-IS
Extensions for Segment Routing", draft-ietf-isis-segment-
routing-extensions-13 (work in progress), June 2017.
[I-D.ietf-ospf-ospfv3-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3
Extensions for Segment Routing", draft-ietf-ospf-ospfv3-
segment-routing-extensions-10 (work in progress),
September 2017.
[I-D.ietf-ospf-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", draft-ietf-ospf-segment-
routing-extensions-22 (work in progress), November 2017.
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing
Architecture", draft-ietf-spring-segment-routing-13 (work
in progress), October 2017.
[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>.
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[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>.
Authors' Addresses
Ran Chen
ZTE Corporation
No.50 Software Avenue,Yuhuatai District
Nanjing, Jiangsu Province 210012
China
Phone: +86 025 88014636
Email: chen.ran@zte.com.cn
Shaofu Peng
ZTE Corporation
No.68 Zijinghua Road,Yuhuatai District
Nanjing, Jiangsu Province 210012
China
Email: peng.shaofu@zte.com.cn
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