udp port binding with multicast

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From: killkolor (anonymous_at_discussions.microsoft.com)
Date: 06/05/04 

Date: Sat, 5 Jun 2004 06:01:06 -0700

hello,

i am trying to make a simple udp application and encountered a problem with the port binding. i isolated the critical part in an console application with some try and catche's and came to this conclusions:

if i only bind the udp client to a port this works fine
if i don't bind the udp client to an explicit port (overload constructor without arguments) the JoinMulticastGroup works fine
--> if i bind the udp client to a specific port and try the JoinMulticastGroup on this instance, i get an exception (code: 10049) that says: the adress is not valid in this context

what i did is to turn off my firewall and disconnect everything from the internet, so it's really local. unfortunately still the same exception.

is there something i have to set in my system to allow a multicast on a specific port?

is there alternatively a way to find out what port i get, if i don't use an argument in the constructor, so i can send it as an endpoint to other multicast clients?

thx
killkolor

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