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Re: [Linux-cluster] Multicast for GFS?

> Can you explain why this should be INADDR_ANY rather than the local IP address?

i knew i forgot something... 

i've been having some trouble with
        memcpy(&mreq.imr_interface, he->h_addr, he->h_length);

since it contains my mcast addr instead of real host addr. I'm debugging
it now to see where the error happens... 

Temporarly, I've changed it to htonl(INADDR_ANY)... 
seems like "temporarly" is a bit streching term for me :) 

> You also mentioned in another email that the "cman_tool leave" should issue 
> a setsockopt to leave the multicast group, does this not happen automatically 
> when the socket is closed? 

Actually no. When you close the socket that was a member of Mcast Group,
node does not sent "IGMP leave" message to router, so mcast packets
continue to arrive until router issues "membership refresh" procedure
(which, depending on configuration, is at every 30 seconds). 

If node does not confirm it's membership (and it won't since kernel
can't find any socket for the multicast group), mcast path gets pruned
at a router, but stays valid for another 2-3 minutes (also depending on

> If it isn't then cman_tool leave can do this I
> suppose. In the case where the cluster software exits without the help of
> cman_tool it will be fenced anyway so there shoudn't be a problem :-)

That's true for fenced nodes, but it's not a clean solution, so, if it
isn't much of a trouble, I'd really like to have membership drop
implemented before socket gets closed.

Lazar Obradovic, System Engineer
laza YU net
YUnet International http://www.EUnet.yu
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