Request for IETF Input: Reuse of Protocol Number 33

Allison Mankin <> Thu, 19 May 2005 21:24 UTC

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From: Allison Mankin <>
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Date: Thu, 19 May 2005 17:22:29 -0400
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Subject: Request for IETF Input: Reuse of Protocol Number 33
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Protocols which can be encapsulated in IP datagrams must be assigned a
Protocol Number as defined in RFC2780. This number is used in an 8
bit field the IP header ("Protocol" in IPv4, "Next Header" in IPv6) to
identify the encapsulated protocol. Due to the limited range of
available values, it is desirable to recycle numbers, although not
sought in general by the IESG. Current assignments may be found at

The Datagram Congestion Control Protocol (recently approved)
has requested from IANA that it be permitted to reuse the
Protocol Number 33, currently assigned to the Sequential Exchange
Protocol (SEP). It is believed that this protocol has not been used
for many years. The protocol author, Jon Crowcroft, confirms this

This note initiates a two week last call (to end 3 June 2005) to
solicit any indication that SEP is in active use. If there is no
indication by the date above, the IESG will let IANA know that
Protocol Number 33 may be assigned to DCCP, and that the
use of 33 for SEP will be considered OBSOLETE.

Public comments may be sent to Private comments may
be sent to the Responsible Area Director, Allison Mankin,

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