[Live-devel] what's mean of this sentence?

[Ross Finlayson]

> I have found out that Live555 uses TTL 0 multicast message in order to find its own IP address.

Yes, this is the *first* thing that it tries, because - despite what you might think - is an approach that is very effective and portable across many different OSs.

However, it's important to realize that this is not the *only* technique that it tries.  If the 'multicast loopback' technique fails, then the code then tries a second technique - one that is more conventional, but less portable:
	- Call "gethostname()" to get the computer's domain name; then
	- Call "getaddrinfo()" (or "gethostbyname()" if "getaddrinfo()" is not available), to resolve this name into an IP address.

If both of these techniques (multicast loopback and "gethostname()"/"getaddrinfo()") fail, then it usually means that your network interface is not configured properly.


> Solution like that might sound dubious, but there must be a reasonable explanation for such an implementation.
> Network configurations? Portability? Although it seems that it creates more problems (on some network configurations, including mine).

Actually, on most configurations, it works just fine.


> I just switched to usual IP query

I don't know what "usual IP query" is supposed to mean, but - as noted above - you should check to make sure that your network interface is configured properly (and has a router for 224.0.0.0/8 - i.e., for IP multicast).

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/

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