Invalid TLV Handling in IS-IS
draft-ginsberg-lsr-isis-invalid-tlv-01

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Last updated 2018-12-02
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LSR Working Group                                            L. Ginsberg
Internet-Draft                                                  P. Wells
Updates: 3563 5305 6232 6233 (if                           Cisco Systems
         approved)                                                 T. Li
Intended status: Standards Track                         Arista Networks
Expires: June 5, 2019                                      T. Przygienda
                                                                S. Hegde
                                                  Juniper Networks, Inc.
                                                        December 2, 2018

                     Invalid TLV Handling in IS-IS
                 draft-ginsberg-lsr-isis-invalid-tlv-01

Abstract

   Key to the extensibility of the Intermediate System to Intermediate
   System (IS-IS) protocol has been the handling of unsupported and/or
   invalid Type/Length/Value (TLV) tuples.  Although there are explicit
   statements in existing specifications, in some cases the expected
   behavior is "well known" but not explicitly stated.

   This document discusses the "well known behaviors" and makes them
   explicit in order to insure that interoperability is maximized.

   This document when approved updates RFC3563, RFC5305, RFC6232, and
   RFC6233.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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
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   Drafts is at https://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

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   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 June 5, 2019.

Copyright Notice

   Copyright (c) 2018 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
   (https://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.  TLV Codepoints Registry . . . . . . . . . . . . . . . . . . .   3
   3.  TLV Acceptance in PDUs  . . . . . . . . . . . . . . . . . . .   4
     3.1.  Handling of Disallowed TLVs in Received PDUs  . . . . . .   4
     3.2.  Special Handling of  Disallowed TLVs in Received Purges .   4
     3.3.  Applicability to sub-TLVs . . . . . . . . . . . . . . . .   5
     3.4.  Correction to POI TLV Registry Entry  . . . . . . . . . .   5
   4.  TLV Validation and LSP Acceptance . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The Intermediate System to Intermediate System (IS-IS) protocol
   utilizes Type/Length/Value (TLV) encoding for all content in the body
   of Protocol Data Units (PDUs).  New extensions to the protocol are
   supported by defining new TLVs.  In order to allow protocol
   extensions to be deployed in a backwards compatible way an
   implementation is required to ignore TLVs that it does not
   understand.  This behavior is also applied to sub-TLVs, which are
   contained within TLVs.

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