[Linux-cluster] Howto multicast?

[Harri.Paivaniemi at tietoenator.com]

Please explain me,

I havn't use multicasting very much so now I have problems to understand this RHCS 5- communication.

I have tought it goes this way:

- cman uses either broadcast or multicast nowadays (multicast by default)
- openais uses always multicast, with it's default address

Is this right? What is the difference there - if we have openais communicating, why there is another thing also communicating? I have been told that openais is cman's communication channel so what the heck?

So, If I have 2 clusters in the same subnet, how to tell these things to be different?


D. Teigland says:

""
When openais is started by cman, the openais.conf file is not used.  Many of
the configuration parameters listed in openais.conf can be set in cluster.conf
instead.

See the openais.conf man page for the specific parameters that can be set in
these sections.  Note that settings in the <clusternodes> section will
override any comparable settings in the openais sections above (in particular,
bindnetaddr, mcastaddr, mcastport and nodeid will always be replaced by values
in <clusternodes>).
""

So, if I put in cluster.conf:

<clusternode....>
<multicast addr="239.192.204.100" interface="bond0"/>

... for each node, what it configures? Cman or openais? 

You see, if I do that, log says still:

--------
openais[15321]: [MAIN ] Using default multicast address of 239.192.204.175
----------

And then, I could also tell in <cman...>, that

<multicast addr="239.192.204.100" interface="bond0"/>

... but what it configures? Still netstat -g shows only that default address there...


So if somebody knows, how this goes, please tell me. Please...


-hjp





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