Clarification of the Use of the IS-IS Generic Information TLV
draft-bowers-lsr-isis-gen-info-clarifications-00

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LSR                                                            C. Bowers
Internet-Draft                                     Juniper Networks Inc.
Intended status: Standards Track                       February 22, 2021
Expires: August 26, 2021

     Clarification of the Use of the IS-IS Generic Information TLV
            draft-bowers-lsr-isis-gen-info-clarifications-00

Abstract

   This document clarifies some aspects of [RFC6823], "Advertising
   Generic Information in IS-IS".

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].

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
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   This Internet-Draft will expire on August 26, 2021.

Copyright Notice

   Copyright (c) 2021 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
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   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.  Associating Information Carried in GENINFO TLVs with
       Information Carried in Other IS-IS Advertisements . . . . . .   2
   3.  Associating Information Carried in GENINFO TLVs with
       Information Carried in Other IS-IS Instances  . . . . . . . .   3
   4.  Congruent and Incongruent Instances . . . . . . . . . . . . .   3
   5.  Leaking the GENINFO TLV . . . . . . . . . . . . . . . . . . .   3
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   [RFC6823] defines the Generic Information TLV for carrying non-
   routing information in IS-IS.  The current document clarifies some
   aspects of [RFC6823].

2.  Associating Information Carried in GENINFO TLVs with Information
    Carried in Other IS-IS Advertisements

   In order to avoid duplicating information sent in IS-IS
   advertisements, it is useful for an application to be able to
   associate information carried in application-specific GENINFO APPsub-
   TLVs with the underlying objects being described by other IS-IS
   advertisements.  This is allowed as long as the requirements of
   Section 6 of [RFC6823] are met.

   As an example, an application may need to learn the latency of a
   particular link using the existing Unidirectional Link Delay sub-
   TLV(#33) carried in TLV#22, while at the same time using an
   application-specific GENINFO APPsub-TLV to distribute application-
   specific information about the same link.  If the APPsub-TLV carries
   the System ID of the neighbor together with an interface identifier,
   and the TLV#22 that carries the Unidirectional Link Delay sub-TLV
   also carries an interface identifer, then the application can
   uniquely identify the underlying link being described by the two
   advertisements.

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   A document that specifies how an application-specific GENINFO TLV is
   used should also specify how associations of information in different
   advertisements should be made.

3.  Associating Information Carried in GENINFO TLVs with Information
    Carried in Other IS-IS Instances

   [RFC8202] specifies a mechanism for multiple IS-IS protocol instances
   to share the same circuit by including the IID-TLV in the PDUs