IPv6 Jumbograms
RFC 2675
Document | Type |
RFC - Proposed Standard
(August 1999; Errata)
Obsoletes RFC 2147
|
|
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Authors | David Borman , Steve Deering , Bob Hinden | ||
Last updated | 2013-03-02 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 2675 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
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 header, immediately following the IPv6 header. This option has an alignment requirement of 4n + 2. (See [IPv6, Section 4.2] for discussion of option alignment.) The option has the following format: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Show full document text