A PCN encoding using 2 DSCPs to provide 3 or more states

The information below is for an old version of the document
Document Type Expired Internet-Draft (pcn WG)
Last updated 2010-02-10 (latest revision 2009-04-08)
Replaces draft-moncaster-pcn-3-state-encoding
Stream IETF
Intended RFC status (None)
Expired & archived
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Stream WG state WG Document
Document shepherd None
IESG IESG state Expired
Consensus Boilerplate Unknown
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


Pre-congestion notification (PCN) is a mechanism designed to protect the Quality of Service of inelastic flows within a controlled domain. It does this by marking packets when traffic load on a link is approaching or has exceeded a threshold below the physical link rate. This experimental encoding scheme specifies how three encoding states can be carried in the IP header using a combination of two DSCPs and the ECN bits. The Basic scheme only allows for three encoding states. The Full scheme provides 6 states, enough for limited end- to-end support for ECN as well.


Bob Briscoe (bob.briscoe@bt.com)
Moncaster T (toby.moncaster@bt.com)
Michael Menth (menth@informatik.uni-wuerzburg.de)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)