Technical Summary
This document specifies TCP-Friendly Multicast Congestion Control
(TFMCC). TFMCC is a source-based, single-rate congestion control
scheme that builds upon the unicast TCP-Friendly Rate Control
mechanism (TFRC) (RFC3448). TFMCC is stable and responsive under a wide
range of network conditions and scales to receiver sets on the order
of several thousand receivers. To support scalability, as much
congestion control functionality as possible is located at the
receivers. Each receiver continuously determines a desired receive
rate that is TCP-friendly for the path from the sender to this
receiver. Selected receivers then report the rate to the sender in
feedback packets. TFMCC is designed to be reasonably fair when competing
for bandwidth with TCP flows.
TFMCC is a building block as defined in RFC 3048.
Working Group Summary
There is strong consensus to publish this document with the intention to gain
experience and later re-submit it for standards track.
Protocol Quality
The TFMCC algorithm described in this protocol is based on its Unicast
counterpart (TFRC) published as IETF RFC 3448. It was extensively
tested through simulations by the authors and by others (Mark Pullen
and associates, see RMT WG archives), that provided feedback based on
their independent simulations. The feedback has been addressed by the
authors.
We know of at least one successful implementation of TFMCC by Brian
Adamson, who incorporated it in its implementation of the RMT "NORM"
protocol and who also provide feedback to the authors.
The responsible AD was Magnus Westerlund and Lorenzo Vicisano the
WG shepherd.
Note to RFC Editor
NEW: Add to end of section 1. Introduction Prior to 1.1.
Statement of Intent
This memo contains part of the definitions necessary to fully
specify a Reliable Multicast Transport protocol in accordance with RFC
2357. As per RFC 2357, the use of any reliable multicast protocol in
the Internet requires an adequate congestion control scheme. This
document specifies an experimental congestion control scheme. While
waiting for initial deployment and experience to show this scheme to
be effective and scalable, the IETF publishes this scheme in the
"Experimental" category.
It is the intent of the Reliable Multicast Transport (RMT) Working
Group to re-submit the specification as an IETF Proposed Standard as
soon as the scheme is deemed adequate.