[AG-TECH] Multicast beacon questions

Chris Greenhalgh cmg at Cs.Nott.AC.UK
Tue Oct 30 05:25:01 CST 2001


> with out logging in to the VirtualVenues i tried running this and i get
> an error message "Cannot bind requested address",
> after logging in i get "cannot bind:requested address in use"
>
> i tried to trace the problem, this message is coming from RtpMonitor code,
>  but couldnt figure out the exact cause for this exception.

The problem is probably either:
a) an app tries to bind a unicast udp socket to the session's specific port,
e.g. to send from (this is not necessary, since packets can be sent to the
session from any port) or
b) there is/was a bug in the low level networking (e.g. native
implementation of java.net.MulticastSocket) which was not setting the (BSD
sockets) SO_REUSEADDR socket option (or equivalent), which allows other
sockets to bind to (i.e. receive packets sent to) the same address.

the (unix & windows) command line command 'netstat -a' will give an idea of
what end points are bound on that machine.

Chris





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