[OpenSIPS-Users] A behavior of Clusterer module during networking issues

[Donat Zenichev]

Hi there!
I have question and it's almost theoretic.
The question relates to Clusterer module and its behavior.

Lets imagine we have a regular Active/Stand-by setup.
And both instances are sharing the same sharing tag, for e.g.: "vip/1"

This cluster also has some automatic tool kit that handles:
- shared IP migration
- shared tag activation

One day a networking failure happens on Active (Master) side,
and Stand-by side decides to allocate shared IP address on itself,
and also Stand-by machine activates shared tag (sets it to active).

For a while, Stand-by side acts as Active machine and everything works
great.

But, since that failure with a regular Master, was networking related issue.
And, operation system keeps on working on regular Master,
then a regular Master also supposes itself as a real Active node, and it
thinks that
it's Stand-by side that is unreachable and not-working, meanwhile it's not
true.

What happens with a sharing tag, when a Master side comes back into play?
(no more networking issues)
Master keeps on working (all the time) with already present active "vip/1"
shared tag.
So when Master returns into work, and meets Stand-by side, they both have
active shared tag.

Will Clusterer module solve this contradiction on its own?
And if so, to which side the precedence is given?

The other way around could be to manually re-activate all services,
when all the cluster resumes into normal working process (all nodes are
present).
Thus this gives us a warranty that shared tag will only be activated on one
of the sides.

Any answer is appreciated.

-- 

Best regards,
Donat Zenichev
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