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Re: UDP Broadcast uses random source ports
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Re: UDP Broadcast uses random source ports

Title: Re: UDP Broadcast uses random source ports
That may be true for busy networks.  It is not always the case.  In our case, we want to use satellite (and other) broadcasts.  Obviously, it will have to be UDP.  We want the receiver to be able to establish a listener port and be able to select the UDP port.  In our case, the “network” will likely consist of a receiver and a single user (or at most, a few users).  So I am definitely interested in this discussion.


On 8/31/11 2:18 AM, "Jens Alfke" <email@hidden> wrote:

I don’t have an answer to your exact question (been too long since I used UDP), but I can tell you that it’s a bad idea to use broadcast. It will create work for the network interface and IP stack of every single device on the LAN, because every device has to listen to all broadcast packets. This is a bad idea on busy networks.

What you should be using instead is link-local multicast. It has the same basic behavior, except that only network interfaces that are explicitly listening on your multicast address will handle the packet; others can just ignore it. This is how Bonjour works, for example. (And it was Stuart “Bonjour” Cheshire who first explained to me the difference, ten years ago.)

 
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