Nic to nic connection on clustered servers, why?

We are replacing our CAT5 cable with CAT6 and found that that the Windows Server 2003, Enterprise Edition Node1 and Node2 servers are linked to each other via a CAT5 cable running between the servers to their second nic card. The first nic's on each are connected to the switch like a normal server.
This resulted in the network connection being broken when the cable CAT5 cable to the switch was swapped for CAT6 which also means the connection to the network has no backup. In this particular case, Node1 lost the connection and Node2 does not take over automatically, it needed to be enabled.

Is it normal for clustered servers node1 and node2 to be linked directly via nic and rj45 cable and what is the function of this connection?

Should a third additional NIC be installed to backup nic one?
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No, I wouldn't think that you'd need a 3rd NIC in either Server...

... I persume you understand that the configuration you've described is perfectly normal and is the correct way to setup a failover cluster.

So, you've swapped out all 3 cables to CAT6 and now you want to revert back to Node 1 as the primary?  (is that the question?)
canfly6Author Commented:
Thanks for the comments.

>>graye...the question was ...?is it normal?..

The "heartbeat" cable was not changed because we did not understand it's function and after reading the data in the link offered by TheCleaner it would appear that the data  transfer via this connector is so small that there is no need to switch the cable to CAT6, infact, it sounds like we could put those GigaByte connections to better use.

We know how to switch nodes.
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Yes, the heartbeat doesn't have to be anything great...a 10/100Mb NIC or similar will do just fine.
canfly6Author Commented:
Thank you for the points.
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