I have a questiuon regarding the heartbeat messgage exchange.

Currently i have 2 cluster systems, each consisting of 2 node:
- cluster A consists of nodes A1, A2
- cluster B consists of nodes B1, B2

All 4 nodes are attached with bonded interface to a tow LAN
switches SW1 and SW2 (lets call it normal LAN).

A1 and A2 (and B1 and B2) have a direct interconnection where
the DRBD devices are syncronized plus a serial cable (lets call it
DRBD LAN)

Thus currently cluster A (and B) use 3 different ways to exchange
the heartbeat packages:
- bcast ofer the DRDB LAN
- ucast using normal lan
- the serial cable

Now i figured out the cluster A needs states/data from cluster B 
(and vice versa) for some fail-over decisions.

I see 2 possible solutions:
a) wrting a resource agent which polls the state from the other cluster
and i use this state
b) i configure 1 single cib.xml with 2 "sub-clusters"

With sub-cluster i mean certain resource run only on cluster A and other
resource run only on B.

My question now:
* what will happen if one of the nodes is disconnected from the normal
LAN - are the information tunnled over the redundant connections?

Scenario: A1 is disconnected from SW1. A2 still recieves HB packages 
via the serial line and the DRBD LAN. Do B1 and B2 see A1 as dead or
do the get the information about A1 via A2?

maybe strange scenario but i have it (but unfortunatly i can not test it out
because some external constraints .... managers! ;-)

kind regards Max
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