Internet DRAFT - draft-yang-idr-bgp-redundancy-policy
draft-yang-idr-bgp-redundancy-policy
IDR Working Group F. Yang
Internet-Draft X. Geng
Intended status: Standards Track T. Zhou
Expires: 14 September 2023 Huawei
13 March 2023
Advertising Redundancy Policy in BGP
draft-yang-idr-bgp-redundancy-policy-01
Abstract
Redundancy Protection is a generalized protection mechanism by
replicating and transmitting copies of flow packets on redundancy
node over multiple different and disjoint paths, and further
eliminating the redundant packets at merging node. In order to
support the replication behavior of redundancy protection, Redundancy
Policy is used to instruct the replication of service packets and
assign more than one redundancy forwarding paths. This document
defines the extensions to BGP to advertise the redundancy policy.
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
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 14 September 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. BGP Extensions to Redundancy Policy . . . . . . . . . . . . . 3
3.1. Flag Sub-TLV . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Redundancy Policy with a Redundancy Segment . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
4.1. Existing Registry: BGP Tunnel Encapsulation Attribute
sub-TLVs . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Redundancy protection [I-D.ietf-spring-sr-redundancy-protection] is a
generalized protection mechanism by replicating and transmitting
copies of flow packets on redundancy node over multiple different and
disjoint paths, and further eliminating the redundant packets at
merging node. To support the replication on the redundancy node,
Redundancy Segment[I-D.ietf-spring-sr-redundancy-protection] and
Redundancy Policy[I-D.geng-spring-redundancy-policy] are specified
respectively. Redundancy Segment is the variation of Binding SID to
associate with a Redundancy Policy, instantiation of which provides
segment lists of more than one disjoint paths. Redundancy Policy is
a variant of SR Policy [I-D.ietf-spring-segment-routing-policy], and
shares the basic structure and elements with SR Policy. Different
from SR policy, a new attribute Flag is added to indicate the type of
the Candidate Path as redundancy type, which means all the Segment-
Lists in this candidate path are used to forward the different copies
of service traffics.
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This document defines the extensions to Border Gateway Protocol (BGP)
to distribute the redundancy policy information. As a variant of SR
policy, Redundancy Policy reuses the BGP extensions to SR policy
candidate path and other information distribution specified in
[I-D.ietf-idr-segment-routing-te-policy]. In addition, a new sub-TLV
is defined in this document to support the distribution of new
attribute of redundancy policy.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. BGP Extensions to Redundancy Policy
As a variant of SR policy, redundancy policy uses the same Subsequent
Address Family Identifier (SAFI) whose NLRI identifies an SR Policy
candidate path. The Tunnel Type identifier for SR Policy and a set
of sub-TLVs specifying segment lists of the SR Policy candidate path,
as well as other information about the SR Policy are reused. The
content of Redundancy Policy Candidate Path is encoded in the Tunnel
Encapsulation Attribute [RFC9012] by using the same Tunnel-Type of SR
Policy Type.
The redundancy policy encoding structure is as follows:
SR Policy SAFI NLRI: <Distinguisher, Policy-Color, Endpoint>
Attributes:
Tunnel Encaps Attribute (23)
Tunnel Type: SR Policy
Binding SID
SRv6 Binding SID
Redundancy Flag
Preference
Priority
Policy Name
Policy Candidate Path Name
Explicit NULL Label Policy (ENLP)
Segment List
Segment
Segment
...
...
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3.1. Flag Sub-TLV
Redundancy policy introduces a new attribute Flag to indicate the
type of Candidate Path as redundancy type. Correspondingly, a new
Flag sub-TLV is defined to be attached at the candidate path level as
a sub-TLV. The Flag sub-TLV is optional and MUST NOT appear more
than once in the Redundancy Policy encoding.
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(TBD1) | Length | Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Candidate Path Flag Sub-TLV
where:
* Type: to be allocated by IANA.
* Length: specifies the length of the value field not including Type
and Length fields.
* Flags: 1 octet of flags. It is requested to IANA to create a new
registry "SR Policy Candidate Path Flags" . One flag is defined at
this writing:
0
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|R|U|U|U|U|U|U|U|
+-+-+-+-+-+-+-+-+
where:
Candidate Path Flags
R-Flag: This flag encodes the redundancy policy behavior
U-Flag: Unused and unassigned
* RESERVED: 1 octet of reserved bits. SHOULD be set to zero on
transmission and MUST be ignored on receipt.
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3.2. Redundancy Policy with a Redundancy Segment
Redundancy Policy can be optionally associated with a Binding
Segment, which can only be Redundancy Segment. When there is a
Redundancy Segment associated with Redundancy Policy, Redundancy
Segment is required to be distributed by the Binding SID Sub-TLV or
SRv6 Binding SID Sub-TLV defined in section 2.4.2 and 2.4.3 of
[I-D.ietf-idr-segment-routing-te-policy] respectively. In SRv6, the
endpoint behavior End.R of Redundancy Segment is required to be
distributed with SRv6 Binding SID at the same time.
4. IANA Considerations
4.1. Existing Registry: BGP Tunnel Encapsulation Attribute sub-TLVs
This document defines new sub-TLVs in the registry "BGP Tunnel
Encapsulation Attribute sub-TLVs" that has been assigned codepoints
by IANA as follows via the early allocation process:
Codepoint Description Reference
-----------------------------------------------------
TBD Flag sub-TLV This I-D
5. Security Considerations
TBD
6. Normative References
[I-D.geng-spring-redundancy-policy]
Yang, F., Geng, X., Zhou, T., and G. S. Mishra,
"Redundancy Policy for Redundancy Protection", Work in
Progress, Internet-Draft, draft-geng-spring-redundancy-
policy-04, 24 July 2022,
<https://datatracker.ietf.org/doc/html/draft-geng-spring-
redundancy-policy-04>.
[I-D.ietf-idr-segment-routing-te-policy]
Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P.,
Jain, D., and S. Lin, "Advertising Segment Routing
Policies in BGP", Work in Progress, Internet-Draft, draft-
ietf-idr-segment-routing-te-policy-20, 27 July 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-
segment-routing-te-policy-20>.
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[I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
P. Mattes, "Segment Routing Policy Architecture", Work in
Progress, Internet-Draft, draft-ietf-spring-segment-
routing-policy-22, 22 March 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
segment-routing-policy-22>.
[I-D.ietf-spring-sr-redundancy-protection]
Geng, X., Chen, M., Yang, F., Camarillo, P., and G. S.
Mishra, "SRv6 for Redundancy Protection", Work in
Progress, Internet-Draft, draft-ietf-spring-sr-redundancy-
protection-02, 23 September 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
sr-redundancy-protection-02>.
[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>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9012] Patel, K., Van de Velde, G., Sangli, S., and J. Scudder,
"The BGP Tunnel Encapsulation Attribute", RFC 9012,
DOI 10.17487/RFC9012, April 2021,
<https://www.rfc-editor.org/info/rfc9012>.
Authors' Addresses
Fan Yang
Huawei
156 Beiqing Rd.
Beijing
100095
China
Email: shirley.yangfan@huawei.com
Xuesong Geng
Huawei
156 Beiqing Rd.
Beijing
100095
China
Email: gengxuesong@huawei.com
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Tianran Zhou
Huawei
156 Beiqing Rd.
Beijing
100095
China
Email: zhoutianran@huawei.com
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