[e2e] ECN vs. source quench

[David P. Reed]

At 08:18 PM 4/23/2004, Black_David at emc.com wrote:
>ECN for UDP -  really??  How is it reflected back to the source
>and what does the source do with it?

Protocols implemented on top of UDP can make use of ECN information to do 
their own (presumably "tcp compatible") congestion control, using whatever 
control loops they implement on top of UDP.

For example, a "digital fountain" can rate-control its transmission source 
to back off when congestion is encountered, even though "digital fountains" 
never retransmit.

As I said, ECN is an IP layer function and has nothing to do with TCP in 
particular - all it does is tell the endpoint about impending congestion 
conditions the IP datagram encountered as it traversed the routers along 
the route.