Background: OK, so I am trying to Multicast for a large deployment we have coming up in the next month. Recently installed the R3 release to make use of the Prestaged media, quick collection refresh, and fast AD updates, etc. Normal image deployment is working great as per normal. I enabled the multicast on the Distribution Point and took the defaults. (enabed, checked. Use multicast service point's computer account. Obtain IP address from DHCP server. UDP Port range 63000-64000. Schedule not enabled. Transfer rate 100Mbps) The client boots to PXE, select the task sequence, does its thing until Apply Operating System when it sits at "Opening Multicast". It does not fail and it does not move. It just sits there. I had situations where it failed before, but this doesn't. I can look at the Resource monitor on the server (Win 2008 R2) and see "svchost.exe (WDSServer)" sending on IP address "239.0.0.192". Working with my network admin and Cisco support (we have a Cisco 4510 core switch client and server plugged into the same switch). Using "sh ip mroute" we can see the 239.0.0.192 is linked to my server 172.16.0.78. Using "sh ip igmp snooping group vlan 1 | inc 239.0.0.192" we see "VLAN 1, Group 239.0.0.192, Version v2, Port list g5/12 g5/13 Po10". This shows that the clients are joining the server created multicast group. The server is sending and not closing the connection, but the clients are not moving. This has worked in the past. Then it didn't. Then it did. Etc. Upgraded to R3 and again not working. What I have done so far: I have uninstalled PXE, WDS, and Multicast using: http://social.technet.microsoft.com/Forums/en/configmgrosd/thread/1f6ac299-d069-4c3a-9d09-ba541493c9bc http://blogs.technet.com/b/configurationmgr/archive/2009/08/05/configmgr-2007-multicast-os-deployments-may-fail-after-applying-kb971413.aspx http://blogs.technet.com/b/configurationmgr/archive/2011/01/05/troubleshooting-the-pxe-service-point-and-wds-in-configuration-manager-2007.aspx I have tried changing the Multicast tab to use 224.0.0.1 thru 224.0.0.255 before and this worked for a short time. However our Cisco support engineer informed us we shouldn't be using the 224 range because it could conflict with Cisco "stuff"...I don't entirely follow. I may end up trying this again, but they are Wireshark mirroring ports and craziness on the newtork side now. http://social.technet.microsoft.com/Forums/en/configmgrosd/thread/bbde2371-2ea8-4399-a9f6-282d2a8cb74c http://social.technet.microsoft.com/Forums/en-US/configmgrosd/thread/b3de3ba0-3e93-4cd2-a492-0bdc42a01700/ Question: Where can I go from here? Suggestions? Find this post helpful? Does this post answer your question? Be sure to mark it appropriately to help others find answers to their searches.

Have you already tried the obvious? Examining multicast related logfiles? See http://technet.microsoft.com/en-us/library/bb932135.aspx, "Multicast for Operating System Deployment Log Files"Torsten Meringer | http://www.mssccmfaq.de

Yes we did and all appeared normal. Found the problem. It was in the Cisco switch configuration. Checking it yesterday, after a core network switch outage, where the VMs shutdown due to host isolation rules and then were restarted the MULTICASTING WORKED. The IP changed depending on how long we left in between multicasts so the changing IP thing didn't seem to matter. This made no sense until we checked which Port-channel the SCCM server was on. It changed from Port-channel 10 to Port-channel 8. This meant the VM migrated from one ESX host to another ESX host. Now that we found it was working on one host and not another we checked the Port-channel configurations. Port-channel 10 that did NOT work had: interface Port-channel10 description BASD-ESX02 - Virtual Machines switchport switchport mode access service-policy input POLICE storm-control broadcast level 20.00 storm-control action trap spanning-tree portfast end Port-channel 8 that did work had my original configuration on it: interface Port-channel8 description BASD-ESX01 - Virtual Machines switchport switchport mode access spanning-tree portfast end Final Resolution: The "service-policy input POLICE" on the Port-channel configuration was the culprit. Removed that from all Port-channels for the VMware servers and the Multicast works on all four ESX hosts even when Live migrating during a multicast from Host to Host. All that uninstalling and reinstalling and the Network guys are the problem! Bah! Find this post helpful? Does this post answer your question? Be sure to mark it appropriately to help others find answers to their searches.