Replication Policy for Redundant Protection
draft-geng-spring-redundancy-policy-00
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Xuesong Geng , Mach Chen | ||
| Last updated | 2020-03-09 | ||
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| IESG | IESG state | I-D Exists | |
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draft-geng-spring-redundancy-policy-00
Network Working Group X. Geng
Internet-Draft M. Chen
Intended status: Experimental Huawei
Expires: September 10, 2020 March 09, 2020
Replication Policy for Redundant Protection
draft-geng-spring-redundancy-policy-00
Abstract
Redundancy protection is a method of service protection by sending
copies of the same packets of one flow over multiple paths, which
includes packet replicaiton, elimination and ordering. This document
defines redundancy policy as an extension to the current SR policy to
support redundancy protection.
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 .
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 10, 2020.
Copyright Notice
Copyright (c) 2020 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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publication of this document. Please review these documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology and Conventions . . . . . . . . . . . . . . . . . 2
3. Redundancy Protection Introduction . . . . . . . . . . . . . 3
4. Replication Policy . . . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
8. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Redundancy protection is a method of providing 1+1 protection by
sending copies of the same packets of one flow over multiple paths,
which includes packet replicaiton, elimination and ordering. This
document defines redundancy policy to support redundancy protection.
2. Terminology and Conventions
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].
Redundancy Node: the start point of redudancy protection, which is a
network device that could implement packet replication.
Merging Node: the end point of redudancy protection, which is a
network node that could implement packet elimination and
ordering(optionally).
Redundancy Policy: an extended sr policy which includes more than one
active segment lists to support redudancy protection.
Editor's Note: Similar mechanism is defined as "Service Protection"
in the [RFC8655]. In this document, we define a new term "Redundancy
Protection" to distinguish with other service protection method.
Some of the terms are the similar as [RFC8655].
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3. Redundancy Protection Introduction
The figure shows how to provide redundancy protection in an Segment
Routing Domain.
| |
|<---------------SR Domain--------------->|
| |
| +------+T2+----+ |
+---+ +---+ +-+-+ +-+-+ +---+ +---+
| E1+----| In|--+T1+--+Red| |Mer|--+T4+--| Eg+----+ E2|
+---+ +---+ +-+-+ +-+-+ +---+ +---+
+-----+T3+-----+
The process of redundancy protection is as follows: 1) The flow is
replicated in Reb(Redundancy Node); 2) Tow replicated flows go
through different paths till Mer (Merging Node); When there is any
failures happened in one the path, the service continues to deliver
through the other path without break; 3) The first received packet of
the flow is transmitted from Mer (Merging Node) to Eg(Egress), and
the redundant packets are eliminated. 4) Sometimes, the packet will
arrive out of order because of redundancy protection, the function of
reordering may be necessary in the Merging Node.
In this document, we introduces Redundancy Policy as a variation of
Segment Routing Policy defined in
[I-D.ietf-spring-segment-routing-policy] to support redundancy
protection. Redundancy policy applys equally to both SR-MPLS and
SRv6.
4. Replication Policy
Redundancy Policy is used to enable packet replication and
instantiation more than one ordered lists of segments between
replicaiton node and merging node to steer the same flow through
different paths in an SR domain.
A Redundancy Policy is identified through the tuple <replicaiton
node, redundancy ID, merging node>. Redundancy node is specified as
IPv4/IPv6 address of the head end, which is able to do packet
replication. Merging node is specified as IPv4/IPv6 address of the
end point, which is able to do packet elimination and
ordering(optional). Repliation ID could be a specifed value of
"color" define in section 2.1 of
[I-D.ietf-spring-segment-routing-policy], which indicates the sr
policy as a redundancy policy. Replicaiton ID could also be used to
distinguish redundancy policy sharing the same redundancy node and
merging node.
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The following elements are extended in Redundancy Policy:
o Redundancy ID: is used to distinguish different redundancy policy
o Redundancy SID: is variation of Binding SID for Redundancy policy.
Redundancy SID will be instantiated as Redundancy Policy in
redundancy node. Redundancy SID is define in draft-geng-spring-
redundancy-protection-sid-00
o Candidate path: more than one candidate paths are included in
redundancy policy. In each candidate path, the last segment
SHOULD be merging SID. Merging SID is defined in draft-geng-
spring-redundancy-protection-sid-00. The preference of the
candidate path is used to select the best candidate path for an SR
Policy. The preference of candidate paths in redundancy policy
SHOULD be the same .
A packet is steered into a Redundancy policy at a redundancy node in
similar ways of SR policy defined in section 8 of
[I-D.ietf-spring-segment-routing-policy]:
o Incoming packets have an active SID matching the redundancy SID at
the redundancy node;
o Incoming packets match a BGP/Service route which recurses on an SR
policy (BGP should be extended to support matching to a redundancy
policy, which is supposed to be covered in the following work);
o Per-flow Steering: incoming packets match or recurse on a
forwarding array of where some of the entries are Rplication
Policy.
o Policy-based Steering: incoming packets match a routing policy
which directs them on a redundancy policy.
5. IANA Considerations
TBD
6. Security Considerations
TBD
7. Acknowledgements
Thank you for valuable comments from James Guichard and Andrew Mail
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8. Normative References
[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", draft-
ietf-spring-segment-routing-policy-06 (work in progress),
December 2019.
[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>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>.
Authors' Addresses
Xuesong Geng
Huawei
Email: gengxuesong@huawei.com
Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
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