Network Working Group S. Zhuang Internet-Draft Z. Li Intended status: Standards Track Sam aldrin Expires: February 22, 2015 Huawei Technologies J. Tantsura G. Mirsky Ericsson August 21, 2014 BGP Link-State Extensions for Seamless BFD draft-zhuang-idr-bgp-ls-sbfd-extensions-00 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 February 22, 2015. Zhuang, et al. Expires February 22, 2015 [Page 1] Internet-Draft BGP-LS Extensions for S-BFD August 2014 Copyright Notice Copyright (c) 2014 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 (http://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 and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as 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. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 9.1. Normative References . . . . . . . . . . . . . . . . . . 7 9.2. Informative References . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction [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. [I-D.ginsberg-isis-sbfd-discriminator] defines a mean of advertising one or more S-BFD Discriminators using the IS-IS Router Capability TLV. [I-D.bhatia-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 Zhuang, et al. Expires February 22, 2015 [Page 2] Internet-Draft BGP-LS Extensions for S-BFD August 2014 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. Zhuang, et al. Expires February 22, 2015 [Page 3] Internet-Draft BGP-LS Extensions for S-BFD August 2014 [I-D.ginsberg-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 19) | +-----------------------------+ | Length (multiple of 4) | 1 +-----------------------------+ | Discriminator Value(s) | 4/Discriminator : : +-----------------------------+ Figure 1: S-BFD Discriminators Sub-TLV [I-D.bhatia-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 Sub-TLV Type - S-BFD Discriminator TLV Type 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. Zhuang, et al. Expires February 22, 2015 [Page 4] Internet-Draft BGP-LS Extensions for S-BFD August 2014 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.ginsberg-isis-sbfd- discriminator] and [I-D.bhatia-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 5. Operation In an inter-as VPN network as follows, ASBR1 and ASBR2 establish a BGP-LS session for exchanging S-BFD Discriminators information. Zhuang, et al. Expires February 22, 2015 [Page 5] Internet-Draft BGP-LS Extensions for S-BFD August 2014 |-------------------| |-----------------| | AS1 | | AS2 | ----- | ------ | | | |CE1|--- |PE1 |------| | | | ----- | ------ | | | | | | | S-BFD | | | | | Discriminators | | | | | Exchanging via | | | | | BGP-LS | | | -------- | <----------> | -------- ----- | ----- | |----| ASBR1|--------------------| ASBR2|--|PE3|---|CE3| | | -------- | | -------- ----- | ----- ----- | ------ | | | |CE2|--- |PE2 | | | | ----- | ------ | | | | | | | |-------------------| |-----------------| |<-----------S-BFD Connectivity Test----------->| PE1/PE2 PE3 Step 1: ASBR1 learns all the S-BFD Discriminators information within AS1 by the mean defines in [I-D.ginsberg-isis-sbfd-discriminator] or [I-D.bhatia-ospf-sbfd-discriminator]. Step 2: ASBR1 sends AS1's S-BFD Discriminators information to AS2's ASBR2 via the BGP-LS session. Step 3: ASBR2 injects the AS1's S-BFD Discriminators information receiving from ASBR1 into IGP (IS-IS or OSPF or OSPFv3), then flood them within the domain of the AS2 via IGP, So the nodes of AS2 can learn all the S-BFD Discriminators information originating from AS1. Likewise, the nodes of AS1 can learn all the S-BFD Discriminators information originating from AS2. At this point, we can use S-BFD Procedures defines in [I-D.ietf-bfd- seamless-base] between the PEs which belong to different AS. 6. IANA Considerations TBD. Zhuang, et al. Expires February 22, 2015 [Page 6] Internet-Draft BGP-LS Extensions for S-BFD August 2014 7. Security Considerations This document does not introduce any new security risk. 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, March 1997. 9.2. Informative References [I-D.bhatia-ospf-sbfd-discriminator] Bhatia, M., Ranganath, T., Pignataro, C., and S. Aldrin, "OSPF extensions to advertise S-BFD Target Discriminator", draft-bhatia-ospf-sbfd-discriminator-00 (work in progress), May 2014. [I-D.ginsberg-isis-sbfd-discriminator] Ginsberg, L., Akiya, N., and M. Chen, "Advertising S-BFD Discriminators in IS-IS", draft-ginsberg-isis-sbfd- discriminator-00 (work in progress), May 2014. [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-02 (work in progress), August 2014. [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-05 (work in progress), May 2014. [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. Zhuang, et al. Expires February 22, 2015 [Page 7] Internet-Draft BGP-LS Extensions for S-BFD August 2014 [RFC4971] Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate System to Intermediate System (IS-IS) Extensions for Advertising Router Information", RFC 4971, July 2007. [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, October 2008. Authors' Addresses Shunwan Zhuang Huawei Technologies Huawei Bld., No.156 Beiqing Rd. Beijing 100095 China Email: zhuangshunwan@huawei.com 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 Zhuang, et al. Expires February 22, 2015 [Page 8] Internet-Draft BGP-LS Extensions for S-BFD August 2014 Greg Mirsky Ericsson 300 Holger Way San Jose CA 95134 USA Email: gregory.mirsky@ericsson.com Zhuang, et al. Expires February 22, 2015 [Page 9]