IS-IS OSPF K. Kompella Internet-Draft Juniper Networks, Inc. Intended status: Standards Track October 30, 2016 Expires: May 3, 2017 IGP Extensions for Resilient MPLS Rings draft-kompella-isis-ospf-rmr-00 Abstract This document describes the use of IS-IS and OSPF for discovering Resilient MPLS Rings (RMR). RMR relies on the IGP for discovery of the ring elements and properties, as well as subsequent changes to the ring topology. Details of auto-discovery and operation are given in the RMR architecture document; this document simply describes the formats of RMR-related constructs in IS-IS and OSPF. 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 [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 May 3, 2017. Copyright Notice Copyright (c) 2016 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 Kompella Expires May 3, 2017 [Page 1] Internet-Draft IGP Extensions for Resilient MPLS Rings October 2016 (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 1.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 2 2. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 4 2.1. Provisioning . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Announcement . . . . . . . . . . . . . . . . . . . . . . 5 3. Security Considerations . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.1. Normative References . . . . . . . . . . . . . . . . . . 7 5.2. Informative References . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction Rings are a very common topology in transport networks. A ring is the simplest topology offering link and node resilience. Rings are nearly ubiquitous in access and aggregation networks. As MPLS increases its presence in such networks, and takes on a greater role in transport, it is imperative that MPLS handles rings well; this is not the case today. The RMR architecture document [I-D.ietf-mpls-rmr] describes the motivations and operation of RMR. RMR uses protocols such as IS-IS [RFC5305] and OSPF[RFC3630] for auto-discovery, and RSVP-TE [RFC3209] and LDP [RFC5036] for signaling LSPs. This document gives the specifics of Type-Length-Value (TLV) formats for IS-IS and OSPF. 1.1. Definitions For a more detailed description, see [I-D.ietf-mpls-rmr]. A ring is a subgraph of a given graph G = (V, E), consisting of a subset of n nodes {R_i, 0 <= i < n}. The directed edges {(R_i, R_i+1) and (R_i+1, R_i), 0 <= i < n-1} must be a subset of E (note that index arithmetic is done modulo n). We define the direction from node R_i to R_i+1 as "clockwise" (CW) and the reverse direction as "anticlockwise" (AC). As there may be several rings in a graph, we number each ring with a distinct ring ID RID. Kompella Expires May 3, 2017 [Page 2] Internet-Draft IGP Extensions for Resilient MPLS Rings October 2016 R0 . . . R1 . . R7 R2 Anti- | . Ring . | Clockwise | . . | Clockwise v . RID = 17 . v R6 R3 . . R5 . . . R4 Figure 1: Ring with 8 nodes The following terminology is used for ring LSPs: Ring ID (RID): A non-zero number that identifies a ring; this is unique in some scope of a Service Provider's network. A node may belong to multiple rings. Ring node: A member of a ring. Note that a device may belong to several rings. Node index: A logical numbering of nodes in a ring, from zero upto one less than the ring size. Used purely for exposition in this document. Ring master: The ring master initiates the ring identification process. Mastership is indicated in the IGP by a two-bit field. Ring neighbors: Nodes whose indices differ by one (modulo ring size). Ring links: Links that connnect ring neighbors. Express links: Links that connnect non-neighboring ring nodes. Ring direction: A two-bit field in the IGP indicating the direction of a link. The choices are: UN: 00 undefined link CW: 01 clockwise ring link AC: 10 anticlockwise ring link EX: 11 express link Ring Identification: The process of discovering ring nodes, ring links, link directions, and express links. Kompella Expires May 3, 2017 [Page 3] Internet-Draft IGP Extensions for Resilient MPLS Rings October 2016 The following notation is used for ring LSPs: R_k: A ring node with index k. R_k has AC neighbor R_(k-1) and CW neighbor R_(k+1). RL_k: A (unicast) Ring LSP anchored on node R_k. CL_jk: A label allocated by R_j for RL_k in the CW direction. AL_jk: A label allocated by R_j for RL_k in the AC direction. P_jk (Q_jk): A Path (Resv) message sent by R_j for RL_k. 2. Theory of Operation Say a ring has ring ID RID. The ring is provisioned by choosing one or more ring masters for the ring and assigning them the RID. Other nodes in the ring may also be assigned this RID, or may be configured as "promiscuous". Ring discovery then kicks in. When each ring node knows its CW and AC ring neighbors and its ring links, and all express links have been identified, ring identification is complete. Once ring identification is complete, each node signals one or more ring LSPs RL_i. RL_i, anchored on node R_i, consists of two counter- rotating unicast LSPs that start and end at R_i. A ring LSP is "multipoint": any node R_j can use RL_i to send traffic to R_i; this can be in either the CW or AC directions, or both (i.e., load balanced). Both of these counter-rotating LSPs are "active"; the choice of direction to send traffic to R_i is determined by policy at the node where traffic is injected into the ring. The default is to send traffic along the shortest path. Bidirectional connectivity between nodes R_i and R_j is achieved by using two different ring LSPs: R_i uses RL_j to reach R_j, and R_j uses RL_i to reach R_i. 2.1. Provisioning For the purposes of RMR, a ring node R is configured with its loopback address, the RID that it will participate in, and what link- state IGP to use for auto-discovery. R is also configured with a mastership value, which is used in master election. Finally, R may be configured with the signaling protocols and OAM protocols it supports, or these may be inferred. Note that R may participate in multiple rings; each would have its own configuration. To simplify ring provisioning even further, R may be made "promiscuous" by being assigned an RID of 0. A promiscuous node listens to RIDs in its IGP neighbors' link-state updates in order to acquire an RID for its use. Details are in [I-D.ietf-mpls-rmr]. Kompella Expires May 3, 2017 [Page 4] Internet-Draft IGP Extensions for Resilient MPLS Rings October 2016 2.2. Announcement Once configured, R announces its configuration parameters in the IGP via an RMR Node TLV. The RMR Node TLV may contain sub-TLVs; in particular, the RMR Neighbor TLV. At a high level, these TLVs are as follows. [RMR Node Type][RMR Node Length][RID][Node Flags][sub-TLVs] Ring Node TLV Structure [RMR Nbr Type][RMR Nbr Length][Nbr Address][Nbr Flags] Ring Neighbor Sub-TLV Structure In IS-IS, the RMR Node TLV is a new top-level TLV. The specific format 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 (TBD) | Length = 6+S | Ring ID (4 octets) ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... (RID continued) | Node Flags (2 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sub-TLVs, if any ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ S is the total size of the sub-TLVs Ring Node TLV Format 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 (TBD) | Length = n*6 | Neighbor Loopback ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... (continued, 4 octets) | Neighbor Flags (2 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Neighbor Loopback (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Neighbor Flags (2 octets) | (etc.) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ n = number of neighbors included in the sub-TLV Ring Neighbor sub-TLV Format In OSPF, the RMR Node TLV is a new top-level TLV of the Traffic Engineering Opaque LSA. Kompella Expires May 3, 2017 [Page 5] Internet-Draft IGP Extensions for Resilient MPLS Rings October 2016 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 (TBD) | Length = 8+S | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ring ID (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Node Flags (2 octets) | Pad (2 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | sub-TLVs ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Pad is set to zero when sending and ignored on receipt. S = total length of sub-TLVs OSPF Ring Node TLV Format 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 (TBD) | Length = 6*N | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Neighbor Loopback (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Neighbor Flags (2 octets) | Pad (2 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Neighbor Loopback (4 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Neighbor Flags (2 octets) | Pad (2 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... etc. | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Pad is set to zero when sending and ignored on receipt. OSPF Neighbor sub-TLV Format 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |MV |SS | SO | MBZ |SU |M| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ MV: Mastership Value SS: Supported Signaling Protocols (10 = RSVP-TE; 01 = LDP) SO: Supported OAM Protocols (100 = BFD; 010 = CFM; 001 = EFM) SU: Signaling Protocol to Use (00 = none; 01 = LDP; 10 = RSVP-TE) M : Elected Master (0 = no, 1 = yes) Flags for a Ring Node TLV Kompella Expires May 3, 2017 [Page 6] Internet-Draft IGP Extensions for Resilient MPLS Rings October 2016 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |RD |OAM| MBZ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ RD: Ring Direction OAM: OAM Protocol to use (00 = none; 01 = BFD; 10 = CFM; 11 = EFM) Flags for a Ring Neighbor TLV 3. Security Considerations It is not anticipated that either the notion of MPLS rings or the extensions to link-state IGPs to support them will cause new security loopholes. As this document is updated, this section will also be updated. 4. IANA Considerations IANA is requested to assign a new top-level TLV for the RMR Node TLV from the IS-IS TLV Codepoints Registry. IANA is also requested to create a new registry for sub-TLVs of the RMR Node TLV. IANA is also requested to assign a new top-level type for the RMR Node TLV from the OSPF TE TLVs Registry. IANA is also requested to create a new registry for sub-TLVs of the RMR Node TLV. 5. References 5.1. Normative References [I-D.ietf-mpls-rmr] Kompella, K. and L. Contreras, "Resilient MPLS Rings", draft-ietf-mpls-rmr-03 (work in progress), October 2016. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . 5.2. Informative References [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, . Kompella Expires May 3, 2017 [Page 7] Internet-Draft IGP Extensions for Resilient MPLS Rings October 2016 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, DOI 10.17487/RFC3630, September 2003, . [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., "LDP Specification", RFC 5036, DOI 10.17487/RFC5036, October 2007, . [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, DOI 10.17487/RFC5305, October 2008, . Author's Address Kireeti Kompella Juniper Networks, Inc. 1133 Innovation Way Sunnyvale, CA 94089 USA Email: kireeti.kompella@gmail.com Kompella Expires May 3, 2017 [Page 8]