[Icecast] is there a way to do a "push relay"?

[David Baelde]

I'm not sure to understand all the details of your setup, but
liquidsoap could be handy. It can act as icecast from the source
client, and relay streams to one or several icecast servers. If you
can run it on server1, that's a solution. The only downside is that by
design, liquidsoap will re-encode the stream.
--
David
http://savonet.sf.net