IPv6 Jumbograms ACP/WGN/SGN1 meeting (Malmo, Sweden, March 2006)
ACP/SGN1 WP/805xx
21/03/06
AERONAUTICAL COMMUNICATIONS PANEL (ACP)
Working Group N - NETWORKING
SUBGROUP N1 – Internet Communications Services
7th meeting
Malmo, Sweden, March 27th – 31st, 2006
IPv6 Jumbograms
Prepared by Pramuk Rungrojaree
Summary
This paper describes the definition of a jumbogram and the changes needed to be done to TCP and UDP packets to make use of this feature.
TABLE OF CONTENTS
1 Introduction 3
2 Definition OF Jumbograms 3
3 Application of jumbograms in Atn 3
4 practical implementation scenario 3
5 proposed amendment to IP sarps 4
6 recomendation 4
REFERENCES
[1] Draft ICAO/ATN Internet Communication Service over the Internet Protocol Suite (IPS), Part 1, March 2006
[2] RFC 2675 IPv6 Jumbograms, August 1999.
[3] RFC 2460 Internet Protocol Version 6 (IPv6) Specification, December 1998.
[4] RFC 793 Transmission Control Protocol, September 1981.
[5] RFC 768 User Datagram Protocol, August 1980.
1 Introduction
IPv6 has been selected as an alternative for the ATN and currently ATN IPv6 SARPs is under development. The use of Jumbograms is one of the benefits of IPv6 that makes it possible to carry large packets via network. This paper describes the definition of a jumbogram and the changes needed to be done to TCP and UDP packets to make use of this feature.
2 Definition OF Jumbograms
A “jumbogram” is an IPv6 packet containing a payload larger than 65,535 eight-bit bytes (also known as octets). The regular IPv6 header has a 16-bit Payload Length field and, therefore, supports payloads up to 65,535 octets long. However, the Jumbo Payload option uses an IPv6 hop-by-hop option, which 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 (232-1) in length.
3 Application of jumbograms in Atn
The implementation of ATSMHS, the ATN’s ground-ground application, had begun in various organizations to create a more efficient environment for sending/receiving binary information. It is foreseen that there will be different types of the information traveling on the network and some types can generate large amount of data such as multimedia information. Therefore the ability to quickly send larger packets via network, the main advantage of jumbograms, could be very beneficial.
4 practical implementation scenario
The Jumbo Payload option is relevant only for IPv6 nodes that may be attached to links whose link MTUs are greater than 65,575 octets (40 octets of the IPv6 header plus 65,535 octets of Payload). The Jumbo Payload option is not required to be implemented or understood by other IPv6 nodes that do not support attachment to links with MTU greater than 65,575. The MTU must not be greater than 65,575 octets if other nodes attached to that links do not support jumbo payload option
The UDP header has a 16-bit Length field which prevents it from making use of jumbograms, and though the TCP header does not have a Length field, both the TCP MSS option and the TCP Urgent field are constrained to 16 bits. Therefore, an implementation of TCP or UDP on an IPv6 node that supports the Jumbo Payload option must include the enhancements specified in RFC 2675, IPv6 Jumbograms.
Conclusively, in order for a network to support Jumbograms, all the nodes in the network should implement Jumbo Payload option. Furthermore, the UDP and TCP protocols in those nodes also have to be enhanced. Because of future benefit of Jumbogram, this feature should be added to the standards. However, the vendors are not very interested in implementing this feature at the present. Therefore, it should be included in the standard as optional feature to support future generation of products.
5 proposed amendment to IP sarps
Following is the proposed amendment to Draft IPS SARPs regarding Jumbograms.
5.4.1 Transmission Control Protocol (TCP)
TCP shall be implemented with the following RFCs:· RFC-793 and RFC-3168, for end-to-end services
· RFC-1323, for High Performance Extensions
· RFC-3168, for Explicit Congestion Notification (ECN)
· RFC-4022, for Management Information Base for the TCP
· (Optional) RFC-2675, for IPv6 Jumbograms
5.4.2 User Datagram Protocol (UDP)
The UDP services shall be implemented in accordance with following RFCs:· RFC-768, for User Datagram services
· RFC-4113, For Management Information Base for the UDP
· (Optional) RFC-2675, for IPv6 Jumbograms
6 recomendation
It is recommended the SGN1 carefully considers the IPv6 Jumbograms feature and, if the subgroup agrees, endorses the proposed amendment.
4
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