Internet DRAFT - draft-zhuang-idr-bgp-ls-sbfd-extensions
draft-zhuang-idr-bgp-ls-sbfd-extensions
Network Working Group S. Zhuang
Internet-Draft Z. Li
Intended status: Standards Track Sam aldrin
Expires: June 28, 2016 Huawei Technologies
J. Tantsura
G. Mirsky
Ericsson
December 26, 2015
BGP Link-State Extensions for Seamless BFD
draft-zhuang-idr-bgp-ls-sbfd-extensions-01
Abstract
[I-D.ietf-bfd-seamless-base] defines a simplified mechanism to use
Bidirectional Forwarding Detection (BFD) with large portions of
negotiation aspects eliminated, thus providing benefits such as quick
provisioning as well as improved control and flexibility to network
nodes initiating the path monitoring. The link-state routing
protocols (IS-IS, OSPF and OSPFv3) have been extended to advertise
the Seamless BFD (S-BFD) Discriminators.
This draft defines extensions to the BGP Link-state address-family to
carry the S-BFD Discriminators information via BGP.
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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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 June 28, 2016.
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Copyright Notice
Copyright (c) 2015 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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Problem and Requirement . . . . . . . . . . . . . . . . . . . 3
4. BGP-LS Extensions for S-BFD Discriminators Exchanging . . . . 3
5. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
[I-D.ietf-bfd-seamless-base] defines a simplified mechanism to use
Bidirectional Forwarding Detection (BFD)[RFC5880] with large portions
of negotiation aspects eliminated, thus providing benefits such as
quick provisioning as well as improved control and flexibility to
network nodes initiating the path monitoring.
[I-D.ietf-isis-sbfd-discriminator] defines a mean of advertising one
or more S-BFD Discriminators using the IS-IS Router Capability TLV.
[I-D.ietf-ospf-sbfd-discriminator] defines a new OSPF Router
Information (RI) TLV that allows OSPF routers to flood the S-BFD
discriminator values associated with a target network identifier.
This mechanism is applicable to both OSPFv2 and OSPFv3.
The link-state routing protocols (IS-IS, OSPF and OSPFv3) have been
extended to advertise the S-BFD Discriminators. But flooding based
propagation of the S-BFD Discriminators using IGPs is limited by the
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perimeter of the IGP domain. For advertising the S-BFD
Discriminators which span across IGP domains (e.g. multiple ASes),
the Border Gateway Protocol (BGP) is better suited as its propagation
perimeter is not limited like the IGPs.
This draft defines extensions to the BGP Link-state address-family to
carry the S-BFD Discriminators information via BGP.
2. Terminology
This memo makes use of the terms defined in
[I-D.ietf-bfd-seamless-base].
3. Problem and Requirement
Seamless MPLS [I-D.ietf-mpls-seamless-mpls] extends the core domain
and integrates aggregation and access domains into a single MPLS
domain. In a large network, the core and aggregation networks can be
organized as different autonomous systems. Although the core and
aggregation networks are segmented into different autonomous systems,
but an E2E LSP will be created using hierarchical-labeled BGP LSPs
based on iBGP-labeled unicast within each AS, and eBGP-labeled
unicast to extend the LSP across AS boundaries. Meanwhile, the
customer will see only two service-end points in the Seamless MPLS
network. In order to detect the possible failure quickly and protect
the network/trigger re-routing, BFD MAY be used for the Service Layer
(e.g. for MPLS VPNs, PW ) and the Transport Layer, so the need
arises that the BFD session has to span across AS domain.
The link-state routing protocols (IS-IS, OSPF and OSPFv3) have been
extended to advertise the S-BFD Discriminators. But flooding based
propagation of the S-BFD Discriminators using IGPs is limited by the
perimeter of the IGP domain. For advertising the S-BFD
Discriminators which span across IGP domains (e.g. multiple ASes),
the Border Gateway Protocol (BGP) is better suited as its propagation
perimeter is not limited like the IGPs. This draft defines
extensions requirement to the BGP Link-state address-family to carry
the S-BFD Discriminators information via BGP.
4. BGP-LS Extensions for S-BFD Discriminators Exchanging
The BGP-LS NLRI can be a node NLRI, a link NLRI or a prefix NLRI.
The corresponding BGP-LS attribute is a node attribute, a link
attribute or a prefix attribute. BGP-LS
[I-D.ietf-idr-ls-distribution] defines the TLVs that map link-state
information to BGP-LS NLRI and BGP-LS attribute. This document adds
additional BGP- LS attribute TLVs to encode the S-BFD Discriminators
information.
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[I-D.ietf-isis-sbfd-discriminator] defines the following TLVs to
encode the S-BFD Discriminators information.
The ISIS Router CAPABILITY TLV as defined in [RFC4971] will be used
to advertise S-BFD discriminators. A new Sub-TLV is defined as
described below. S-BFD Discriminators Sub-TLV is formatted as
specified in [RFC5305].
No. of octets
+-----------------------------+
| Type (to be assigned by | 1
| IANA - suggested value 20) |
+-----------------------------+
| Length (multiple of 4) | 1
+-----------------------------+
| Discriminator Value(s) | 4/Discriminator
: :
+-----------------------------+
Figure 1: S-BFD Discriminators Sub-TLV for ISIS
Inclusion of the S-BFD Discriminators sub-TLV in a Router Capability
TLV is optional. Multiple S-BFD Discriminators sub-TLVs MAY be
advertised by an IS.
[I-D.ietf-ospf-sbfd-discriminator] defines the following TLVs to
encode the S-BFD Discriminators information. The format of the S-BFD
Discriminator TLV is as follows:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator 2 (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator n (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: S-BFD Discriminators TLV for OSPF
Type - S-BFD Discriminator TLV Type
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Length - Total length of the discriminator (Value field) in octets,
not including the optional padding. The Length is a multiple of 4
octets, and consequently specifies how many Discriminators are
included in the TLV.
Value - S-BFD network target discriminator value or values.
Routers that do not recognize the S-BFD Discriminator TLV Type MUST
ignore the TLV. S-BFD discriminator is associated with the BFD
Target Identifier type, which allows de-multiplexing to a specific
task or service.
These TLVs are mapped to BGP-LS attribute TLVs in the following way.
The new information in the Link-State NLRIs and attributes is encoded
in Type/Length/Value triplets.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Value (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: BGP-LS TLV format
The 2 octet Type field values are defined in Table 1. The next 2
octet Length field encodes length of the rest of the TLV. The Value
portion of the TLV is variable and is equal to the corresponding
Value portion of the TLV defined in
[I-D.ietf-isis-sbfd-discriminator] and
[I-D.ietf-ospf-sbfd-discriminator].
The following 'Node Attribute' TLVs are defined:
+---------------+-------------------------+----------+--------------+
| TLV Code | Description | Length | ISIS/OSPF |
| Point | | | TLV/Sub-TLV |
+---------------+-------------------------+----------+--------------+
| TBD | S-BFD Discriminators | variable | TBD |
| ... | ... | ... | ... |
+---------------+-------------------------+----------+--------------+
Table 1: Node Attribute TLVs
These TLVs can ONLY be added to the Node Attribute associated with
the Node NLRI that originates the corresponding S-BFD Discriminator
TLV.
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5. Operations
Existing BGP and BGP-LS operational procedures apply. No new
operation procedures are defined in this document.
6. IANA Considerations
This document requests assigning code-points from the registry for
BGP-LS attribute TLVs based on table Table 1.
7. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See [RFC6952] for details.
8. Acknowledgements
The authors would like to thank Nan Wu for his contributions to this
work.
9. References
9.1. 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,
<http://www.rfc-editor.org/info/rfc2119>.
9.2. Informative References
[I-D.ietf-bfd-seamless-base]
Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J.
Networks, "Seamless Bidirectional Forwarding Detection
(S-BFD)", draft-ietf-bfd-seamless-base-05 (work in
progress), June 2015.
[I-D.ietf-idr-ls-distribution]
Gredler, H., Medved, J., Previdi, S., Farrel, A., and S.
Ray, "North-Bound Distribution of Link-State and TE
Information using BGP", draft-ietf-idr-ls-distribution-13
(work in progress), October 2015.
[I-D.ietf-isis-sbfd-discriminator]
Ginsberg, L., Akiya, N., and M. Chen, "Advertising S-BFD
Discriminators in IS-IS", draft-ietf-isis-sbfd-
discriminator-02 (work in progress), March 2015.
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[I-D.ietf-mpls-seamless-mpls]
Leymann, N., Decraene, B., Filsfils, C., Konstantynowicz,
M., and D. Steinberg, "Seamless MPLS Architecture", draft-
ietf-mpls-seamless-mpls-07 (work in progress), June 2014.
[I-D.ietf-ospf-sbfd-discriminator]
Bhatia, M., Pignataro, C., Aldrin, S., and T. Ranganath,
"OSPF extensions to advertise S-BFD Target Discriminator",
draft-ietf-ospf-sbfd-discriminator-02 (work in progress),
September 2015.
[RFC4971] Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed.,
"Intermediate System to Intermediate System (IS-IS)
Extensions for Advertising Router Information", RFC 4971,
DOI 10.17487/RFC4971, July 2007,
<http://www.rfc-editor.org/info/rfc4971>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <http://www.rfc-editor.org/info/rfc5305>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<http://www.rfc-editor.org/info/rfc5880>.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<http://www.rfc-editor.org/info/rfc6952>.
Authors' Addresses
Shunwan Zhuang
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: zhuangshunwan@huawei.com
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Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
Sam Aldrin
Huawei Technologies
2330 Central Expressway
Santa Clara CA 95051
Email: sam.aldrin@huawei.com
Jeff Tantsura
Ericsson
200 Holger Way
San Jose CA 95134
USA
Email: jeff.tantsura@ericsson.com
Greg Mirsky
Ericsson
300 Holger Way
San Jose CA 95134
USA
Email: gregory.mirsky@ericsson.com
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