Exchange CAS 2010 and NLB: changing from Unicast to IGMP Multicast

We have a cluster of 2 Exchange 2010 CAS servers running WNLB in Unicast Mode. It all runs fine, except the broadcast flooding on the Cisco switches. Thus, we want to change the NLB configs to IGMP Multicast to stop that.

After changing NLB to multicast, NLB complained that the interfaces were misconfigured and the “configuration conflicts with Cluster: cluster traffic mode differs” and the cluster could not converge.

From the System Logs in event viewer, I saw this: “A duplicate name has been detected on the TCP network.  The IP address of the computer that sent the message is in the data. Use nbtstat -n in a command window to see which name is in the Conflict state.”

Another error in the NLB manager itself: “Cluster IP address (172.16.xx.xx) not added to TCPIP properties.”

Each CAS server has 2 dedicated NIC's, one for LAN and the other for NLB.

Any suggestions as to what I am missing when making this change from Unicast to Multicast? Do I need to add the NLB Cluster VIP  to each NIC?

Thanks.
alibrisAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

msmamjiCommented:
It seems to be default behavior.
http://support.microsoft.com/kb/264645
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
alibrisAuthor Commented:
Thanks for the possible answer. We'll have to put the KB to the test. I will update shortly.
0
Senior IT System EngineerIT ProfessionalCommented:
Hi, for the exchange server HT role, what is the correct NLB mode ?

Is that Unicast or IGMP Multicast ?
0
lawlibraryCommented:
I have the same question as above....which is the correct NBL mode?
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Exchange

From novice to tech pro — start learning today.