Internet DRAFT - draft-geng-6man-redundancy-protection-srh
draft-geng-6man-redundancy-protection-srh
IPv6 Maintenance Working Group X. Geng
Internet-Draft M. Chen
Intended status: Standards Track F. Yang
Expires: August 24, 2021 Huawei Technologies
February 20, 2021
SRH Extension for Redundancy Protection
draft-geng-6man-redundancy-protection-srh-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 replication, elimination and ordering. This document
defines SRv6 header (SRH) extensions 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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This Internet-Draft will expire on August 24, 2021.
Copyright Notice
Copyright (c) 2021 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 and Conventions . . . . . . . . . . . . . . . . . 2
3. Redundancy Protection over SRv6 Scenario . . . . . . . . . . 3
4. SRH Extension for Redundancy Protection . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
8. Normative References . . . . . . . . . . . . . . . . . . . . 4
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 replication, elimination and ordering. This
document defines SRv6 header (SRH) extensions 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 redundancy protection, which is a
network device that could implement packet replication.
Merging Node: the end point of redundancy protection, which is a
network node that could implement packet elimination and ordering
(optionally).
Flow Identification: information in SR data service to indicate one
flow.
Sequence Number: information in SR data service to indicate the
packet sequence of one flow.
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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].
3. Redundancy Protection over SRv6 Scenario
The figure shows how to provide redundancy protection over SRv6.
| |
----IPv6--->|<---------------SRv6 Domain------------>|<----IPv6---
| |
| +------+R1+----+ |
+---+ +---+ +-+-+ +-+-+ +---+ +---+
|E1 +----+In +-------+Red| |Mer+--------+Eg +----+E2 |
+---+ +---+ +-+-+ +-+-+ +---+ +---+
+------+R2+----+
As the figure shows, an IPv6 flow is sent out from the end station
E1. The packet of the flow is encapsulated in an outer IPv6+SRH
header in the Ingress(In) and transported through an SRv6 domain. In
the Egress(Eg), the outer IPv6+SRH header of packet is popped, and
the packet is sent to the destination E2.
The process of redundancy protection is as follows: 1) The flow is
replicated in Red (Redundancy Node); 2) Two 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.
This document defines Flow Identification and Sequence Number in
Segment Routing Header(SRH) as an extension of [RFC8754] to support
redundancy protection.
Flow Identification is used to distinguish flows, and Sequence Number
is used to distinguish packets in the same flow when doing packet
merging and ordering.
4. SRH Extension for Redundancy Protection
Flow Identification and Sequence Number could be defined in SRH
optional TLV.
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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 | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow Identification |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: 8 bits, indicates the use of redundancy protection, to be
assigned by IANA.
o Length: 8 bits.
o Reserved: 16 bits. MUST be 0 on transmission and ignored on
receipt.
o Flow Identification: 32 bits, which is used for identifying the
redundant protection flow.
o Sequence Number: 32 bits, which is used for indicating sequence
number of the redundant protection flow.
5. IANA Considerations
This document requires registration of a specific type of TLV used
for redundancy protection in "Segment Routing Header TLVs" registry.
6. Security Considerations
TBD
7. Acknowledgements
Thanks for the valuable comments from James Guichard and Andrew
Malis.
8. 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>.
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[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>.
[RFC8754] Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
(SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
<https://www.rfc-editor.org/info/rfc8754>.
Authors' Addresses
Xuesong Geng
Huawei Technologies
Beijing
China
Email: gengxuesong@huawei.com
Mach(Guoyi) Chen
Huawei Technologies
Beijing
China
Email: mach.chen@huawei.com
Fan Yang
Huawei Technologies
Beijing
China
Email: shirley.yangfan@huawei.com
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