IPv6 Jumbograms
RFC 2675

Document Type RFC - Proposed Standard (August 1999; Errata)
Obsoletes RFC 2147
Last updated 2013-03-02
Stream IETF
Formats plain text pdf html
Stream WG state (None)
Document shepherd No shepherd assigned
IESG IESG state RFC 2675 (Proposed Standard)
Telechat date
Responsible AD (None)
Send notices to (None)
Network Working Group                                          D. Borman
Request for Comments: 2675                      Berkeley Software Design
Obsoletes: 2147                                               S. Deering
Category: Standards Track                                          Cisco
                                                               R. Hinden
                                                                   Nokia
                                                             August 1999
                            IPv6 Jumbograms

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.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   A "jumbogram" is an IPv6 packet containing a payload longer than
   65,535 octets.  This document describes the IPv6 Jumbo Payload
   option, which provides the means of specifying such large payload
   lengths.  It also describes the changes needed to TCP and UDP to make
   use of jumbograms.

   Jumbograms are relevant only to IPv6 nodes that may be attached to
   links with a link MTU greater than 65,575 octets, and need not be
   implemented or understood by IPv6 nodes that do not support
   attachment to links with such large MTUs.

1. Introduction

      jumbo (jum'bO),

          n., pl. -bos, adj.
          -n.
          1. a person, animal, or thing very large of its kind.
          -adj.
          2. very large: the jumbo box of cereal.

          [1800-10; orig. uncert.; popularized as the name of a large
           elephant purchased and exhibited by P.T. Barnum in 1882]

                                              -- www.infoplease.com

Borman, et al.              Standards Track                     [Page 1]
RFC 2675                    IPv6 Jumbograms                  August 1999

   The IPv6 header [IPv6] has a 16-bit Payload Length field and,
   therefore, supports payloads up to 65,535 octets long.  This document
   specifies an IPv6 hop-by-hop option, called the Jumbo Payload option,
   that carries a 32-bit length field in order to allow transmission of
   IPv6 packets with payloads between 65,536 and 4,294,967,295 octets in
   length.  Packets with such long payloads are referred to as
   "jumbograms".

   The Jumbo Payload option is relevant only for IPv6 nodes that may be
   attached to links with a link MTU greater than 65,575 octets (that
   is, 65,535 + 40, where 40 octets is the size of the IPv6 header).
   The Jumbo Payload option need not be implemented or understood by
   IPv6 nodes that do not support attachment to links with MTU greater
   than 65,575.

   On links with configurable MTUs, the MTU must not be configured to a
   value greater than 65,575 octets if there are nodes attached to that
   link that do not support the Jumbo Payload option and it can not be
   guaranteed that the Jumbo Payload option will not be sent to those
   nodes.

   The UDP header [UDP] has a 16-bit Length field which prevents it from
   making use of jumbograms, and though the TCP header [TCP] does not
   have a Length field, both the TCP MSS option and the TCP Urgent field
   are constrained to 16 bits.  This document specifies some simple
   enhancements to TCP and UDP to enable them to make use of jumbograms.
   An implementation of TCP or UDP on an IPv6 node that supports the
   Jumbo Payload option must include the enhancements specified here.

   Note: The 16 bit checksum used by UDP and TCP becomes less accurate
   as the length of the data being checksummed is increased.
   Application designers may want to take this into consideration.

1.1 Document History

   This document merges and updates material that was previously
   published in two separate documents:

   -  The specification of the Jumbo Payload option previously appeared
      as part of the IPv6 specification in RFC 1883.  RFC 1883 has been
      superseded by RFC 2460, which no longer includes specification of
      the Jumbo Payload option.

   -  The specification of TCP and UDP enhancements to support
      jumbograms previously appeared as RFC 2147.  RFC 2147 is obsoleted
      by this document.

Borman, et al.              Standards Track                     [Page 2]
RFC 2675                    IPv6 Jumbograms                  August 1999

2. Format of the Jumbo Payload Option

   The Jumbo Payload option is carried in an IPv6 Hop-by-Hop Options
Show full document text