Byte and Packet Congestion Notification

Document Type Replaced Internet-Draft (individual)
Last updated 2008-08-07 (latest revision 2008-02-25)
Replaced by draft-ietf-tsvwg-byte-pkt-congest
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This memo concerns dropping or marking packets using active queue management (AQM) such as random early detection (RED) or pre- congestion notification (PCN). The primary conclusion is that packet size should be taken into account when transports decode congestion indications, not when network equipment writes them. Reducing drop of small packets has some tempting advantages: i) it drops less control packets, which tend to be small and ii) it makes TCP's bit- rate less dependent on packet size. However, there are ways of addressing these issues at the transport layer, rather than reverse engineering network forwarding to fix specific transport problems. Network layer algorithms like the byte-mode packet drop variant of RED should not be used to drop fewer small packets, because that creates a perverse incentive for transports to use tiny segments, consequently also opening up a DoS vulnerability.


Bob Briscoe (

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