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Path MTU Discovery for IP version 6 (RFC1981)

IP.com Disclosure Number: IPCOM000004261D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2019-Feb-14
Document File: 15 page(s) / 21K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

J. McCann: AUTHOR [+2]

Related Documents

10.17487/RFC1981: DOI

Abstract

This document describes Path MTU Discovery for IP version 6. It is largely derived from RFC 1191, which describes Path MTU Discovery for IP version 4. [STANDARDS-TRACK]

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 11% of the total text.

Network Working Group J. McCann Request for Comments: 1981 Digital Equipment Corporation Category: Standards Track S. Deering Xerox PARC J. Mogul Digital Equipment Corporation August 1996

Path MTU Discovery for IP version 6

Status of this Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Abstract

This document describes Path MTU Discovery for IP version 6. It is largely derived from RFC 1191, which describes Path MTU Discovery for IP version 4.

Table of Contents

1. Introduction.................................................2 2. Terminology..................................................2 3. Protocol overview............................................3 4. Protocol Requirements........................................4 5. Implementation Issues........................................5 5.1. Layering...................................................5 5.2. Storing PMTU information...................................6 5.3. Purging stale PMTU information.............................8 5.4. TCP layer actions..........................................9 5.5. Issues for other transport protocols......................11 5.6. Management interface......................................12 6. Security Considerations.....................................12 Acknowledgements...............................................13 Appendix A - Comparison to RFC 1191............................14 References.....................................................14 Authors’ Addresses.............................................15

McCann, Deering & Mogul Standards Track [Page 1]

RFC 1981 Path MTU Discovery for IPv6 August 1996

1. Introduction

When one IPv6 node has a large amount of data to send to another node, the data is transmitted in a series of IPv6 packets. It is usually preferable that these packets be of the largest size that can successfully traverse the path from the source node to the destination node. This packet size is referred to as the Path MTU (PMTU), and it is equal to the minimum link MTU of all the links in a path. IPv6 defines a standard mechanism for a node to discover the PMTU of an arbitrary path.

IPv6 nodes SHOULD implement Path MTU Discovery in order to discover and take advantage of paths with PMTU greater than the IPv6 minimum link MTU [IPv6-SPEC]. A minimal IPv6 implementation (e.g., in a boot ROM) may choose to omit implementation of Path MTU Discovery.

Nodes not implementing Path MTU Discovery use the IPv6 minimum link MTU defined in [IPv6-SPEC] as the maximum packet size. In most cases, this will result in the use of smaller packets than necessary, because most paths have a PMTU greater than the IPv6 minimum link MTU. A node sending packets much smaller than...

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