SPRING WG Ting. Liao Internet-Draft Ting. Ao Intended status: Standards Track ZTE Corporation Expires: April 21, 2016 October 19, 2015 SPRING IPv6 ListID Encapsulation draft-lt-6man-sr-listid-encapsulation-00.txt Abstract Segment Routing allows a node to steer a packet through an ordered list of instructions, called segments. The ingress node prepends a SR header to a packet containing a set of "segments". A segment can represent any instruction topological or service-based. Segment Routing can be applied to the IPv6 architecture, with a new type of routing extension header. A segment is encoded as an IPv6 address. An ordered list of segments is encoded as an ordered list of IPv6 addresses in the routing extension header. The segment to process is indicated by a pointer in the routing extension header. Upon completion of a segment, the pointer is incremented. This document describes how to decrease the length of the IPv6 list with ListID carried. 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 April 21, 2016. 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 Provisions Relating to IETF Documents Liao & Ao Expires April 21, 2016 [Page 1] Internet-Draft SPRING IPv6 ListID Encapsulation October 2015 (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. Conventions and Abbreviations . . . . . . . . . . . . . . . . 2 3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1.1. SLID Encapsulating . . . . . . . . . . . . . . . . . 4 3.1.1.1. A new type of Routing Extension Header . . . . . 4 3.1.1.2. R-flags defined in draft-previdi-6man-segment- routing-header to identify . . . . . . . . . . . 4 3.1.2. SLID Forwarding . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. Normative References . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction Segment Routing can be applied to the IPv6 data plane with the addition of a new type of Routing Extension Header as described in [I-D.previdi-6man-segment-routing-header]. A segment is encoded as an IPv6 address. An ordered list of segments is encoded as an ordered list of IPv6 addresses in the routing extension header. There may be many specified nodes or links included in the path based on policy, each ipv6 address is 128 bits, this will greatly increase the length of header. This document describes a method by mapping a segment list to a ListID and carrying the ListID in the header. It will decrease the length of the segment routing header. 2. Conventions and Abbreviations 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] . The following notations and abbreviations are used throughout this draft. Liao & Ao Expires April 21, 2016 [Page 2] Internet-Draft SPRING IPv6 ListID Encapsulation October 2015 SR:Segment Routing SID:Segment Identifier SLID: Segment List Identifier, a segment list is identified by a Segment list ID (SLID). 3. Solution In this document, we define the Segment List Identifier (SLID). The segment list is identified by a Segment list ID (SLID). Segment list ID (SLID) is allocated by the controller. The segment list and the SLID can be advertised to the related nodes. When the node receives the mapping message, it generates a mapping table about the SLID to the Segment List. The segment routing header could be a new type of Routing Extension Header, or be identified by the R-flags as defined in [I-D.previdi-6man-segment-routing-header]. 3.1. Example As shown in the figure 1. __ +----------------------+ / _ | Controller | __ / / +----------------------+_ \ / / | | | | | \ \ \ / / | | | | | \ \ \ +---+ / +---+ | | +---+ | +---+ \ \+---+ -------- |R1 |---/---|R3 |--|---|--|R5 |---|-|R7 |---\-- |R9 | +---+ / +---+ | | +---+ | +---+ \ +---+ | / | / \ | \ | \ | | / | / \ | \ | \ | +---+ +---+ +---+ +---+ +---+ |R2 |-------|R4 |--------|R6 |-----|R8 |-------|R10|----------- +---+ +---+ +---+ +---+ +---+ Figure 1 Scenario 1 In this example, we assumes that: o All nodes are SR capable. o Each SR node has a global IPv6 address configured by operator to identify the node. o The operator (likely via the SDN Controller) as provisioned the Node-SIDs 2001::1001, 2001::1002, 2001::1003, 2001::1004, 2001::1005, 2001::1006, 2001::1007, 2001::1008, 2001::1009,and 2001::1010 respectively at nodes R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10. o The controller computes a list for: {R1, R2, R4, R3, R5, R6, R8, R7, R9, and R10}, and allocates an unused ID 2001::1100 to identify the segment list. o The controller advertises the mapping Segment list ID (SLID) 2001::1100 for segment list {R1, R2, R4, R3, R5, R6, R8, R7, R9, and R10} to all the nodes in the list. o Each node receives the mapping message, generates the mapping table of the SLID to the List. Liao & Ao Expires April 21, 2016 [Page 3] Internet-Draft SPRING IPv6 ListID Encapsulation October 2015 3.1.1. SLID Encapsulating 3.1.1.1. A new type of Routing Extension Header A new type of Routing Extension Headers is shown in the figure 2. The ingress node could encapsulate frames with SLID carried. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Header | Hdr Ext Len | Routing Type | Segments Left | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RESV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Segment List ID (128 bits ipv6 address) | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 A new type of Routing Extension Header o Next Header: 8-bit selector. Identifies the type of header immediately following the SRH. o Hdr Ext Len: 8-bit unsigned integer, is the length of the SRH header in 8-octet units, not including the first 8 octets. o Routing Type: TBD, to be assigned by IANA. o Segments Left: It is optional, as defined in [RFC2460], it contains the index, in the Segment List, of the next segment to inspect. Segments Left is decremented at each segment in the list. o RESV: Reserved and for future use. o Segment List ID: 128 bit IPv6 addresses identifying the Segment List. Used to look up the next hop, and then the next hop exchanges the destination of the IPv6 encapsulation. 3.1.1.2. R-flags defined in draft-previdi-6man-segment-routing-header to identify As the R-flags have reserved and defined in [I-D.previdi-6man-segment-routing-header], such as one of R-flags set, it means the SLID instead of the Segment List[n] carrying in the encapsulation, there is no need to carry the segment list[0]...segment list[n] in this solution. 3.1.2. SLID Forwarding As each node receives the mapping message, each node knows which one is the next node of itself. Such as R1 receives the message of Segment list ID (SLID) 2001::1100 mapping to the segment list {R1, Liao & Ao Expires April 21, 2016 [Page 4] Internet-Draft SPRING IPv6 ListID Encapsulation October 2015 R2, R4, R3, R5, R6, R8, R7, R9, and R10}, R1 will know R2 is my next segment in the LIST, and when some packets need to forward on the path of this list, it encapsulates the packet with the SLID 2001::1100 carried, the destination of the packet is the addresses of R2 which is the next segment of R1. When the packet transit to R2, with the next header is routing extension header, and the routing extension header is the type of SLID carried, or the SRH carried with the R-flags to identify the SLID carried. R2 learns the SLID 2001::1100 mapping to the segment list {R1, R2, R4, R3, R5, R6, R8, R7, R9, and R10}, and the next segment of R2 in this list is R4. R2 changes the destination of this packet with the address of R4, and then the packet transits to R4. R4 knows R3, changes the destination,and the packet transits to R3. ... and then R10 receives the packet, it knows itself is the last segment in the list, and decapsulates the IPv6 SR header. 4. Security Considerations TBD. 5. Acknowledgements In progress. 6. IANA Considerations TBD. 7. Normative References [I-D.ietf-spring-segment-routing] Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., and r. rjs@rob.sh, "Segment Routing Architecture", draft- ietf-spring-segment-routing-06 (work in progress), October 2015. [I-D.previdi-6man-segment-routing-header] Previdi, S., Filsfils, C., Field, B., Leung, I., Linkova, J., Kosugi, T., Vyncke, E., and D. Lebrun, "IPv6 Segment Routing Header (SRH)", draft-previdi-6man-segment-routing- header-08 (work in progress), October 2015. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Liao & Ao Expires April 21, 2016 [Page 5] Internet-Draft SPRING IPv6 ListID Encapsulation October 2015 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", RFC 4915, DOI 10.17487/RFC4915, June 2007, . [RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July 2007, . [RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250, July 2008, . Authors' Addresses Ting Liao ZTE Corporation No.50 Software Avenue Nanjing, Jiangsu 210012 China Phone: +86 25 88016576 Email: liao.ting@zte.com.cn Ting Ao ZTE Corporation No.889 Bibo Rd Shanghai 201203 China Phone: +86 21 68897642 Email: ao.ting@zte.com.cn Liao & Ao Expires April 21, 2016 [Page 6]