Network Working Group X. Xu Internet-Draft Huawei Intended status: Standards Track April 28, 2014 Expires: October 30, 2014 BGP Link-State Extensions for SR-based SFC draft-xu-idr-bgp-ls-sfc-extension-00 Abstract The Segment Routing mechanism can be leveraged to realize the service path layer functionality of the Service Function Chaining (i.e, steering traffic through the service function path). The link-state IGPs (i.e., IS-IS and OSPF) have been extended to advertise service information including services and the corrresponding service segment identifiers. For the purpose of building service function paths which span across IGP areas, or even across ASes, this draft defines extensions to the BGP Link-state address-family to carry service information including services and the corrresponding service segment identifiers. 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 October 30, 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 Xu Expires October 30, 2014 [Page 1] Internet-Draft BGP-LS Extensions for SR-based SFC April 2014 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 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. BGP-LS Extensions for SR-based SFC . . . . . . . . . . . . . 3 3.1. Node Attribute TLVs . . . . . . . . . . . . . . . . . . . 3 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 7.2. Informative References . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction [I-D.xu-spring-sfc-use-case] describes a particular use case for SPRING where the Segment Routing (SR) mechanism is leveraged to realize the service path layer functionality of the SFC (i.e, steering traffic through the service function path). To allow the service classifier to encode the segment list represeting a particular service path, the classifier needs to know on which service node(s) a given service is located and what segment ID (SID) is used to indicate that service on a given service node.The link- state IGPs (i.e., IS-IS [I-D.xu-isis-service-sid-adv] and OSPF [I-D.xu-ospf-service-sid-adv]) have been extended to advertise service information including services and the corresponding service SIDs. However, the flooding-based propagation using IGPs is limited by the perimeter of the IGP domain. To address the need for applications that require visibility into LSDB across IGP areas, or even across ASes, the BGP-LS address- family/sub-address-family have been defined that allows BGP to carry LSDB information. The BGP Network Layer Reachability Information (NLRI) encoding format for BGP-LS and a new BGP Path Attribute called BGP-LS attribute are defined in [I-D.ietf-idr-ls-distribution]. The identifying key of each LSDB object, namely a node, a link or a prefix, is encoded in the NLRI and the properties of the object are encoded in the BGP-LS attribute. Xu Expires October 30, 2014 [Page 2] Internet-Draft BGP-LS Extensions for SR-based SFC April 2014 This document describes extensions to BGP-LS to carry service informaiton inlcuding services and their corresponding service SIDs. With such extensions, a service path can be computed across IGP areas, or even across ASes. 1.1. 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]. 2. Terminology This memo makes use of the terms defined in [I-D.ietf-idr-ls-distribution] 3. BGP-LS Extensions for SR-based SFC 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 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 service information currently including services and the corresponding service SIDs. [I-D.xu-isis-service-sid-adv] defines the following two type of TLVs to encode service information: a. Service TLVs b. Service SID Sub-TLVs Therefore, the document defined the corresponding Node Attribute TLVs in the following subsection. 3.1. Node Attribute TLVs The following 'Node Attribute' TLVs are defined: Xu Expires October 30, 2014 [Page 3] Internet-Draft BGP-LS Extensions for SR-based SFC April 2014 +---------------+--------------------+----------+--------------------+ | TLV Code Point| Description | Length | IS-IS Service | | | | | TLV/sub-TLV | +---------------+--------------------+----------+--------------------+ | TBD1 | Service 1 (S1) | variable | Service TLV for S1 | | | | | | | ... | ... | ... | ... | | | | | | | TBDn | Service n (Sn) | variable | Service TLV for Sn | | | | | | | TBDn+1 | Service SID in | variable | MPLS SID Sub-TLV | | | MPLS label format | | | | | | | | | TBDn+2 | Service SID in | variable | IPv6 SID Sub-TLV | | | IPv6 address format| | | +---------------+--------------------+----------+--------------------+ The sections refer to [I-D.xu-isis-service-sid-adv]. These TLVs can ONLY be added to the Node Attribute associated with the Node NLRI that originates the corresponding Service TLV. 4. Acknowledgements TBD. 5. IANA Considerations TBD. 6. Security Considerations This document does not introduce any new security risk. 7. References 7.1. Normative References [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-04 (work in progress), November 2013. [I-D.xu-isis-service-sid-adv] Xu, X., "Signaling Services and Service SIDs Using IS-IS", draft-xu-isis-service-sid-adv-00 (work in progress), April 2014. Xu Expires October 30, 2014 [Page 4] Internet-Draft BGP-LS Extensions for SR-based SFC April 2014 [I-D.xu-ospf-service-sid-adv] Xu, X., "Signaling Services and Service SIDs Using OSPF", draft-xu-ospf-service-sid-adv-00 (work in progress), April 2014. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7.2. Informative References [I-D.xu-spring-sfc-use-case] Xu, X., "Service Function Chaining Use Case", draft-xu- spring-sfc-use-case-00 (work in progress), April 2014. Author's Address Xiaohu Xu Huawei Email: xuxiaohu@huawei.com Xu Expires October 30, 2014 [Page 5]