Win Server 2k3 NLB cant multicast out of VLAN


I have a windows 2003 NLB with 2 servers that is trying to multicast and it cant multicast out of its local vlan/subnet.  I am running VLC server to UDP multicast an MP3 file across the network as a test.  Only people on the same vlan can hear the audio stream.

Our first thought was that it was a multicast routing problem in the network(I am the net admin) but we validated the network setup with Cisco and if we multicast the MP3 file from any other machine other then the cluster it can be heard on any VLAN across the network.  Multicast Routing is working.

So we think its an issue with the NLB.  Perhaps there is a TTL setting that is stuck at 1?

Any help is greatly appreciated.

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BusbarSolutions ArchitectCommented:

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Eric-arupAuthor Commented:
Sorry, still here, got MS and Cisco going at it.  I'll update when I know more.
BusbarSolutions ArchitectCommented:
ou welcome, but I had them before and the same will still apply, I have been an MS before LOL
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Eric-arupAuthor Commented:
Ok so in the long run it turns out it was the app in question sending a TTL of 1.

After a long talk with Cisco, Microsoft basically breaks the multicasting RFC and there are a host of commands you can run on the routers to get around the issue.

You need to be running PIM routing, we run sparse with a RP, and you need to have an ARP entry for the "unicast ip to multicast mac" relationship on your layer 3 devices.  Also you need to have a static mac-address-table command that is on the interfaces that lead back to the server and if you are running a Cisco 6500 you also need to have disable-snooping.  Once we had all that in place the VLC server works fine broadcasting multicast.
Eric-arupAuthor Commented:
Not technically the solution, but A for effort.
BusbarSolutions ArchitectCommented:
perfect Eric, thanks for sharing the info.
can you detail and share the exact configuration, I am so intersted in that
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Windows Server 2003

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