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Optional Checksums in Intermediate System to Intermediate System (ISIS) (RFC3358)

IP.com Disclosure Number: IPCOM000009355D
Original Publication Date: 2002-Aug-01
Included in the Prior Art Database: 2002-Aug-20
Document File: 5 page(s) / 8K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

R. Koodli: AUTHOR [+2]

Abstract

This document describes an optional extension to the Intermediate System to Intermediate System (ISIS) protocol, used today by several Internet Service Proviers (ISPs) for routing within their clouds. ISIS is an interior gateway routing protocol developed originally by OSI and used with IP extensions as Interior Gateway Protocol (IGP). ISIS originally does not provide Complete Sequence Numbers Protocol Data (CSNP) and Partial Sequence Numbers Protocol Data Unit (PSNP) checksums, relying on the underlying layers to verify the integrity of information provided. Experience with the protocol shows that this precondition does not always hold and scenarios can be imagined that impact protocol functionality. This document introduces a new optional Type, Length and Value (TLV) providing checksums.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 34% of the total text.

Network Working Group                                      T. Przygienda

Request for Comments: 3358                                         Xebeo

Category: Informational                                      August 2002

                         Optional Checksums in

           Intermediate System to Intermediate System (ISIS)

Status of this Memo

   This memo provides information for the Internet community.  It does

   not specify an Internet standard of any kind.  Distribution of this

   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This document describes an optional extension to the Intermediate

   System to Intermediate System (ISIS) protocol, used today by several

   Internet Service Proviers (ISPs) for routing within their clouds.

   ISIS is an interior gateway routing protocol developed originally by

   OSI and used with IP extensions as Interior Gateway Protocol (IGP).

   ISIS originally does not provide Complete Sequence Numbers Protocol

   Data (CSNP) and Partial Sequence Numbers Protocol Data Unit (PSNP)

   checksums, relying on the underlying layers to verify the integrity

   of information provided.  Experience with the protocol shows that

   this precondition does not always hold and scenarios can be imagined

   that impact protocol functionality.  This document introduces a new

   optional Type, Length and Value (TLV) providing checksums.

1.  Introduction

   ISIS [ISO90, Cal90a, Cal90b] CSNPs and PSNPs and IIHs can be

   corrupted in case of faulty implementations of L2 hardware or lack of

   checksuming on a specific network technology.  As a particularly ugly

   case, corruption of length and/or TLV length fields may lead to the

   generation of extensive numbers of "empty" LSPs in the receiving

   node.  Since we cannot rely on authentication as a checksum

   mechanism, this document proposes an optional TLV to add checksums to

   the elements.

   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 [Bra97].

Przygienda                   Informational                      [Page 1]

RFC 3358                 SNP Checksums in ISIS               August 2002

2.  TLV Description

   This optional TLV MAY BE included in all CSNP, PSNP and IIH packets

   and an implementation that implements optional checksums MUST accept

   PDUs if they do NOT contain the optional checksum.  Implementations

   that receive an optional checksum TLV and support it MUST discard the

   PDU if the checksum is incorrect.  An implementation that does NOT

   implement optional checksums MUST accept a PDU that contains the...