Network Working Group C. Lin Internet-Draft H. Zhang Intended status: Standards Track HangZhou H3C Co. Limited Expires: January 4, 2014 V. Manral Hewlett-Packard Co. July 5, 2013 Simplified Extension of interface Space for IS-IS draft-lz-isis-relax-interfaces-limit-00 Abstract This document describes a simplified method for extending the interface space beyond the 255 interfaces limit. The proposed mechanism does not require any changes to the IS-IS protocol. 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 December 19, 2013. Copyright Notice Copyright (c) 2012 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. Lin & Zhang & vishwas Expires January 4, 2014 [Page 1] Internet-Draft Simplified Extension of interface Space June 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3 3. Definition of Commonly Used Terms . . . . . . . . . . . . . . . 3 4. Proposed Solution . . . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . . 5 8.2. Informative References . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 Lin & Zhang & vishwas Expires January 4, 2014 [Page 2] Internet-Draft Simplified Extension of interface Space June 2013 1. Introduction The IS-IS specification has an implicit limit of 255 interfaces, as constrained by the eight-bit Circuit ID field carried in various packets. Moderately clever implementers have realized that the only true constraint is that of 255 LAN interfaces, and for that matter only 255 LAN interfaces for which a system is the Designated IS. This is because the only place that the circuit ID is advertised in LSPs is in the pseudo-node LSP ID. Implementers have treated the point-to-point circuit ID number space as being independent from that of the LAN interfaces, since these circuit IDs appear only in IIH PDUs and are only used for detection of a change in identity at the other end of a link. More than 255 point-to-point interfaces have been supported by sending the same circuit ID on multiple interfaces. See [RFC5303]. However, that solution suffers from restrictions required to maintain interoperability with systems that do not support the extensions. This document defines extensions that allow a system to exceed the 255 interfaces limit and do so in a way that has no interoperability issues with systems that do not support the extension. 2. 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]. 3. Definition of Commonly Used Terms This section provides definitions for terms that are used throughout the text. The terminology is consistent with that used in RFC 5311. Originating IS: A physical IS running the IS-IS protocol. As this document describes a method that allows a single physical IS to run additional interfaces in name of multiple extend ISs, the Originating IS represents the single physical IS. Normal system-id: The system-id of an Originating IS as defined by [IS-IS]. Additional system-id: A system-id other than the "Normal system-id", that is assigned by the network administrator to an Extend-IS in order to extend the interface range. The Additional system-id, like the Normal system-id, must be unique throughout the routing area (Level-1) or domain (Level-2), and must be different with the Additional system-id used to extend LSPs in RFC5311. Extending IS: The system, identified by an Additional system-id, for the interfaces beyond 255 to enabled with. Local System: A physical IS running the IS-IS protocol, including Originating IS and Extending ISs. Lin & Zhang & vishwas Expires January 4, 2014 [Page 3] Internet-Draft Simplified Extension of interface Space June 2013 4. Proposed Solution The extension proposed to IS-IS to relax the 255 interfaces limit, Extending IS, same defined as Virtual IS in RFC 5311, is introduced to be only used for extending the interfaces. Circuit index is allocated based on IS, one extended IS 255 more interfaces. Here's the diagrams: R1 R255 \ / I1 ... I255 ____\_______________________/_________ | | | Originating IS | |______________________________________| / \ / \ / \ ________/______ ___\___________ | extending IS' | ... | extending IS" | |_______________| |_______________| / \ / \ I'1 ... I'255 I"1 ... I"255 / \ / \ R'1 R'255 R"1 R"255 Figure 1: Extend interface space by extending IS where Rx are remote routers, Ix are interface to remote routers. When interface space is exceeded, for example I'x and I"x as illustrated in Figure 1 is enabled in the name of extending IS, which means R'x is peered with extending IS' and R"x is peered with extending IS", NOT with Originating IS. The Originating IS MUST specify extending ISs as a neighbor, with metric set to zero. Extending ISs MUST specify the Originating IS as a neighbor with metric set to zero. The adjacency between Originating IS and Extending ISs SHOULD be considered as point-to-point. Hello packet sending Additional system-id is used for the Hello Packets sending on The interface which is running in Extending IS. LSP FLOOD When a new LSP has been received, it must be flooded out some set of the local system's interfaces including Original IS's interfaces and all Extending ISs's interfaces. Also, a self-originated LSP must be flooded out all the local system's interfaces including Original IS's interfaces and all Extending ISs's interfaces. Route Calculation In local system, LSP Database including all Extending ISs's LSP should be used in route calculation. All Extending ISs's interfaces should be used in nexthop calculation. Lin & Zhang & vishwas Expires January 4, 2014 [Page 4] Internet-Draft Simplified Extension of interface Space June 2013 5. Security Considerations This document raises no new security issues for IS-IS. IS-IS security may be used to secure the IS-IS messages discussed here. See [RFC5304]. 6. IANA Considerations This document has no IANA actions. 7. Acknowledgements 8. References 8.1. Normative References [IS-IS] ISO, "Intermediate system to Intermediate system routeing information exchange protocol for use in conjunction with the Protocol for providing the Connectionless-mode Network Service (ISO 8473)," ISO/IEC 10589:2002, Second Edition. [RFC5303] D. Katz,R. Saluja,D. Eastlake 3rd, "Three-Way Handshake for IS-IS Point-to-Point Adjacencies." [RFC5311] Hermelin, A., Previdi, S., and M. Shand, "Simplified Extension of Link State PDU (LSP) Space for IS-IS",RFC 5311, February 2009. 8.2. Informative References [draft-ietf-isis-wg-255adj-02.txt] T. Przygienda, Maintaining more than 255 circuits in IS-IS Authors' Addresses Changwang Lin Oriental Electronic Bld.,2 Chuangye Road, Shang-Di Information Industry Base,Hai-Dian District Beijing P.R.China Email: linchangwang.04414@h3c.com Haifeng Zhang HangZhou H3C Co. Limited 310 Liuhe Road, Zhijiang Science Park Hangzhou P.R. China Email: zhanghf@h3c.com Manral Vishwas Hewlett-Packard Co. USA Email: vishwas.manral@hp.com Lin & Zhang & vishwas Expires January 4, 2014 [Page 5]