Browse Prior Art Database

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.

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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...