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An edge-to-edge Deployment Model for Pre-Congestion Notification: Admission Control over a DiffServ Region

Document Type Expired Internet-Draft (individual in tsv area)
Author Bob Briscoe
Last updated 2015-10-14 (Latest revision 2006-10-25)
Stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
Expired & archived
Stream WG state (None)
Document shepherd (None)
IESG IESG state Expired (IESG: Dead)
Action Holders
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD Lars Eggert
Send notices to (None)

This Internet-Draft is no longer active.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


This document describes a deployment model for pre-congestion notification (PCN) operating in a large DiffServ-based region of the Internet. PCN-based admission control protects the quality of service of existing flows in normal circumstances, whilst if necessary (eg after a large failure) pre-emption of some flows preserves the quality of service of the remaining flows. Each link has a configured- admission-rate and a configured-pre-emption-rate, and a router marks packets that exceed these rates. Hence routers give an early warning of their own potential congestion, before packets need to be dropped. Gateways around the edges of the PCN-region convert measurements of packet rates and their markings into decisions about whether to admit new flows, and (if necessary) into the rate of excess traffic that should be pre-empted. Per-flow admission states are kept at the gateways only, while the PCN markers that are required for all routers operate on the aggregate traffic - hence there is no scalability impact on interior routers.


Bob Briscoe

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