Hi,I just need someone help me to clarify the need of private nic in Exchange 2007 CCR environment. I know it for heartbeat connectivity as it explain on all setup documentations but why the public nic can't also do that? What's the difference?Thank you.

Public Interface :It is used forintranet communication like your clients want to access the server for the its services.It is connected with straight cable or production switch .Private Interface :It is used for heart beat as you know this is used by windows clustering and it always want to know each other and it has different ip and subnet .This is directly connected with each other and by using cross cable .syed.arsalan

1- So the public nic is for Exchange Cluster and private nic is for Windows Cluster?2- When you said different subnet you mean different subnet between private and public nic?Thanks

Not Exactly. What syed is saying is private IP is to maintain the heart beat signals between the two nodes of the cluster. For 2nd question , what he is saying is that range of public IP and private IP should be always different.Raj

The reason why the heart beatshould beonprivate nic is it to avoid traffic on public nic?

Yes. I have always kept node to node traffic over a cross cable across both the nodes. Not even taking the traffic to the core switch or any routing device.Raj

The reason why I'm asking question about private and public nic it's because I see these warnings in event viewer sometime: The node lost communication with cluster node 'MAILBOX2' on network 'Private' The node lost communication with cluster node 'MAILBOX2' on network 'Public' But few sec after communication are back on.

Thats OK. Consider this as a normal and ignore this if they are not very frequent and not creating any fail over issues.Raj

Recommended private "Heartbeat" configuration on a cluster serverhttp://support.microsoft.com/default.aspx/kb/258750Regards,Xiu

Thank you for all your answers and the good link!