A New Internet-Draft is available from the on-line Internet-Drafts directories.
Title : Adaptation Layer Fragmentation Indication
Author(s) : Carsten Bormann
Filename : draft-bormann-intarea-alfi-03.txt
Pages : 10
Date : 2013-03-10
Abstract:
IPv6 defines a minimum MTU of 1280 bytes. Many link layers are more
limited in the maximum size of packets they can communicate. In
order to enable the transport of IP packets that are too large for
these link layers, typically their IP adaptation layers define a
segmentation or fragmentation scheme to transport an IP packet in a
sequence of multiple link layer packets.
Often, adaption layer fragmentation schemes reduce some performance
metric, such as the packet delivery probability. Application or
transport protocols may be able to reduce the maximum size of packets
they send, e.g. by transport layer segmentation or choice of
application layer data object size, which may have less of a
performance impact. It would therefore be desirable for them to know
about any adaptation layer fragmentation that is going on, so they
can choose packet sizes that minimize adaptation layer fragmentation.
At the IP layer, fragmentation can be detected using a number of
mechanisms used in Packetization Layer Path MTU Discovery [RFC4821].
However, adaptation layer fragmentation schemes are often designed to
be "transparent", i.e. there is no way at higher layers to find out
whether they had to be employed (except maybe by elaborate
measurement schemes targeting one of the impacted performance
metrics; this approach does not appear to be viable) [WEI].
The present specification defines a mechanism for IPv6 adaptation
layers to indicate the presence of adaptation layer fragmentation on
one or more hops on the path from an IP sender to an IP receiver, and
to provide an indication of preferred (smaller) packet sizes on these
hops.
The main objective of this version of the draft is to present a
complete design in order to be able to gauge the complexity of the
approach against the gains to be expected from implementing it.
Comments are appreciated and should go to the [email protected]
mailing list.
The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-bormann-intarea-alfi
There's also a htmlized version available at:
http://tools.ietf.org/html/draft-bormann-intarea-alfi-03
A diff from the previous version is available at:
http://www.ietf.org/rfcdiff?url2=draft-bormann-intarea-alfi-03
Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/
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