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Pre-Congestion Notification Encoding Comparison

Document Type Replaced Internet-Draft (individual)
Expired & archived
Authors Kwok Chan , Georgios Karagiannis , T Moncaster , Michael Menth , Philip Eardley , Bob Briscoe
Last updated 2009-03-08
Replaced by RFC 6627
RFC stream (None)
Intended RFC status (None)
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Replaced by draft-ietf-pcn-encoding-comparison
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


A number of mechanisms have been proposed to support differential Qualiy of Service for packets in the Internet. DiffServ is an example of such a mechanism. However, the level of assurance that can be provided with DiffServ without substantial over-provisioning is limited. Pre-Congestion Notification (PCN) uses path congestion information across a PCN region to enable per-flow admission control to provide the required service guarantees for the admitted traffic. While admission control will protect the QoS under normal operating conditions, an additional flow termination mechanism is necessary to cope with extreme events (e.g. route changes due to link or node failure). In order to allow the PCN mechanisms to work it is necessary for IP packets to be able to carry the pre-congestion information to the PCN egress nodes. This document explores different ways in which this information can be encoded into IP packets. This document does not choose the encoding but provide guidance and recommendation based on different criteria. This document also provides a historical trace of the consideration on different encoding alternatives for Pre- Congestion Notification.


Kwok Chan
Georgios Karagiannis
T Moncaster
Michael Menth
Philip Eardley
Bob Briscoe

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