Specification for the Explicit Control Protocol (XCP)

Document Type Expired Internet-Draft (individual in tsv area)
Author Aaron Falk 
Last updated 2015-10-14 (latest revision 2007-01-19)
Stream Internet Engineering Task Force (IETF)
Intended RFC status Experimental
Expired & archived
pdf htmlized (tools) htmlized bibtex
Stream WG state (None)
Document shepherd No shepherd assigned
IESG IESG state Expired (IESG: Dead)
Action Holders
Consensus Boilerplate Unknown
Telechat date
Responsible AD Lars Eggert
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This document contains an initial specification for the Explicit Control Protocol (XCP), an experimental congestion control protocol. XCP is designed to deliver the highest possible end-to-end throughput over a broad range of network infrastructure, including links with very large bandwidth-delay products, which are not well served by the current control algorithms. XCP is potentially applicable to any transport protocol, although initial testing has applied it to TCP in particular. XCP routers are required to perform a small calculation on congestion state carried in each data packet. XCP routers also periodically recalculate the local parameters required to provide fairness. On the other hand, there is no per-flow congestion state in XCP routers. XCP is currently not ready for wide-scale deployment on the public Internet and the intent of this document is to provide a starting point for future experimentation and development as well as to record the authors' implementation experiences and caveats.


Aaron Falk (falk@bbn.com)

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