[Linux-cluster] A better understanding of multicast issues

[Digimer]

Hi all,

  It seems to me that a very good number of clustering problems end up
being multicast and smart switch related. I know that IGMP snooping and
STP are often the cause, and PIM can help solve it. Despite
understanding this, though, I can't quite understand exactly *why* IGMP
snooping and STP break things.

  Reading up on them leads me to think that they should cleanly create
and handle multicast groups, but this obviously isn't the case. When a
switch restarts, shouldn't it send a request to clients asking to
resubscribe to multicast groups? When corosync starts, I expect it would
also send multicast joins.

  Sorry if the question is a little vague or odd. I'm trying to get my
head around the troubles when, on the surface, the docs seem to make the
process of creating/managing multicast quite simple and straight forward.

Thanks!

-- 
Digimer
E-Mail: digimer at alteeve.com
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