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ISIS Working Group                                               H. Chen
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                                  M. Toy
Expires: March 15, 2018                                          Verizon
                                                                  X. Liu
                                                                   Jabil
                                                                  L. Liu
                                                                 Fujitsu
                                                                   Z. Li
                                                            China Mobile
                                                                 Y. Yang
                                                                Sockrate
                                                      September 11, 2017


             ISIS Extensions for Broadcast Inter-AS TE Link
                       draft-chen-isis-ias-lk-01

Abstract

   This document presents extensions to the ISIS protocol for
   advertising broadcast inter-AS Traffic Engineering (TE) links.

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 March 15, 2018.

Copyright Notice

   Copyright (c) 2017 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



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   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  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Conventions Used in This Document . . . . . . . . . . . . . . . 3
   3.  Information on Inter-AS TE Link . . . . . . . . . . . . . . . . 3
   4.  Extensions to ISIS  . . . . . . . . . . . . . . . . . . . . . . 4
     4.1.  sub-TLVs  . . . . . . . . . . . . . . . . . . . . . . . . . 4
     4.2.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . 4
       4.2.1.  ISIS Router Procedure . . . . . . . . . . . . . . . . . 5
       4.2.2.  Super Node Procedure  . . . . . . . . . . . . . . . . . 5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   7.  Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     8.2.  Informative References  . . . . . . . . . . . . . . . . . . 6




























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1.  Introduction

   Connections among different Autonomous Systems (ASes) may be point-
   to-point (P2P) links and broadcast links.  For a P2P inter-AS TE
   link, RFC 5316 defines a new TLV, the inter-AS reachability TLV, for
   advertising the link.

   It also defines three new sub-TLVs for inclusion in the inter-AS
   reachability TLV to carry the information about the neighboring AS
   number and the remote ASBR ID of an inter-AS link.

   For a P2P inter-AS link, the information about its remote ASBR may be
   configured.  For a broadcast inter-AS link, no item configured
   corresponds to the designated router (DR) of the link in ISIS.  Since
   no ISIS runs over any broadcast inter-AS link, no DR is selected.  It
   is hard to configure an item corresponding to the DR on a broadcast
   link.

   This document presents extensions to ISIS for advertising broadcast
   inter-AS TE links through defining a new sub-TLV for a broadcast link
   without configuring any item corresponding to the DR on the link.

2.  Conventions Used in This Document

   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.  Information on Inter-AS TE Link

   For a broadcast link connecting multiple ASBRs in a number of ASes,
   on each of the ASBRs X, the following information about the link may
   be obtained:

     1)  Link Type: Multi-access
     2)  Local IP address with mask length
     3)  Traffic engineering metric
     4)  Maximum bandwidth
     5)  Maximum reservable bandwidth
     6)  Unreserved bandwidth
     7)  Administrative group
     8)  SRLG


   No remote IP address or item corresponding to the DR (i.e., DR's
   interface address) may be obtained.





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4.  Extensions to ISIS

4.1.  sub-TLVs

   Two new sub-TLVs are defined.  One is for local IPv4 address with
   mask length; and the other is for local IPv6 address with mask
   length.

   The format of the sub-TLV for a local IPv4 address with mask length
   is shown 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 (stTBD1)         |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    IPv4 Address (4 bytes)                     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Mask Length  |
     +-+-+-+-+-+-+-+-+


   The IPv4 Address indicates the local IPv4 address of a link.  The
   Mask Length indicates the length of the IPv4 address mask.

   The format of the sub-TLV for a local IPv6 address with mask length
   is illustrated below.

      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 (stTBD2)          |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     IPv6 Address (16 bytes)                   |
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |  Mask Length  |
     +-+-+-+-+-+-+-+-+


   The IPv6 Address indicates the local IPv6 address of a link.  The
   Mask Length indicates the length of the IPv6 address mask.

4.2.  Procedures







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4.2.1.  ISIS Router Procedure

   For a broadcast inter-AS link connecting to multiple ASBRs, each of
   the ASBRs as an ISIS router advertises an LSP with an inter-AS
   reachability TLV, which contains sub-TLVs for the information such as
   1) 10 8) about the broadcast link described in Section 3.  It does
   not contain any sub-TLVs indicating remote ASBR, instead, it includes
   a sub-TLV for the local IP address with network mask.

   When TE is enabled on an inter-AS link and the link is up, the ASBR
   SHOULD advertise this link using the normal procedures for ISIS-TE.
   When either the link is down or TE is disabled on the link, the ASBR
   SHOULD withdraw the advertisement.  When there are changes to the TE
   parameters for the link (for example, when the available bandwidth
   changes), the ASBR SHOULD re-advertise the link but MUST take
   precautions against excessive re-advertisements.

4.2.2.  Super Node Procedure

   Suppose that there is a super node, which just receives LSPs from
   each of ASes (or domains) through a passive ISIS adjacency between
   the super node and an ASBR or a normal router in the AS or domain.

   For a new broadcast link connecting multiple routers, when the super
   node receives an LSP containing the link attached to router X, it
   stores the link from X into its TED.  It finds the link's remote end
   P using the link's local IP address with network mask.  P is a Pseudo
   node identified by the local IP address of the DR selected from the
   routers connected to the link.  After finding P, it associates the
   link attached to X with P and the link connected to P with X. If P is
   not found, a new Pseudo node P is created.  The super node associates
   the link attached to X with P and the link attached to P with X. This
   creates a bidirectional connection between X and P.

   The first router and second router from which the super node receives
   an LSP containing the link are selected as the DR and BDR
   respectively.  After the DR is down, the BDR becomes the DR and the
   router other than the DR with the largest (or smallest) local IP
   address connecting to the link is selected as the BDR.

   When the old DR is down and the BDR becomes the new DR, the super
   node updates its TED through removing the link between each of
   routers X and old P (the Pseudo node corresponding to the old DR) and
   adding a link between each of routers X (still connecting to the
   broadcast link) and new P (the Pseudo node corresponding to the new
   DR).





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5.  Security Considerations

   The mechanism described in this document does not raise any new
   security issues for the ISIS protocols.

6.  IANA Considerations

   This section specifies requests for IANA allocation.

7.  Acknowledgement

   The authors would like to thank all for their valuable comments on
   this draft.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
              RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5316]  Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in
              Support of Inter-Autonomous System (AS) MPLS and GMPLS
              Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316,
              December 2008, <https://www.rfc-editor.org/info/rfc5316>.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, DOI 10.17487/RFC5305,
              October 2008, <https://www.rfc-editor.org/info/rfc5305>.

8.2.  Informative References

   [RFC6805]  King, D., Ed. and A. Farrel, Ed., "The Application of the
              Path Computation Element Architecture to the Determination
              of a Sequence of Domains in MPLS and GMPLS", RFC 6805,
              DOI 10.17487/RFC6805, November 2012,
              <https://www.rfc-editor.org/info/rfc6805>.












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Authors' Addresses

   Huaimo Chen
   Huawei Technologies
   Boston, MA,
   USA

   EMail: Huaimo.chen@huawei.com


   Mehmet Toy
   Verizon
   USA

   EMail: mehmet.toy@verizon.com


   Xufeng Liu
   Jabil
   McLean, VA
   USA

   EMail: Xufeng_Liu@jabil.com


   Lei Liu
   Fujitsu
   USA

   EMail: lliu@us.fujitsu.com


   Zhenqiang Li
   China Mobile
   No.32 Xuanwumenxi Ave., Xicheng District
   Beijing  100032
   P.R. China

   EMail: li_zhenqiang@hotmail.com


   Yi Yang
   Sockrate
   NC
   USA

   EMail: yyang1998@gmail.com




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