Hi Everyone, I'm creating a Windows 7 image for my client and have setup the SCCM 2007 R3 environment and created my Build and Capture task sequence and also a Deployment TS. They have had Novel here in the past (long gone now) and want to be able to use the Multicast features within SCCM as they were successfully using Multicast here using Novel. I'm able to deploy each TS via Unicast with the expected performance (about 1hr to deploy the image) but as soon as I enable my OS image package to use Multicast my deployment time goes from 1hr to 8+ hours! I've been doing a lot of reading on this all over the web and in this forum but I'm not finding anything to check out as a solution for me. Any help would be greatly appreciated! I don't want the answer to my customer to be "sorry, you need to use Unicast". Environment SCCM 2007 R3 Central Site Server running on Windows Server 2008 R2 SCCM 2007 R3 Secondary Site Server running on Windows Server 2008 R2 - holds WDS, DP (Multicast Enabled), MP, SUP and SMP roles Multicast is enabled on the Secondary Site DP and obtains the IP range from the DHCP server. Clients are using the 239.0.0.1 to 239.0.0.254 range. UDP Port Range is default of 63000 - 64000 Do NOT have the "Enable scheduled multicast" checked and have Transfer Rate set to 1GB. I've found these two articles to be good sources of information on the proper settings but to no avail. ConfigMgr 2007: WDS Multicast settings in the Distribution Point properties do not seem to apply http://support.microsoft.com/default.aspx?scid=kb;EN-US;2419357 OSD Multicast IS VERY SLOW http://www.networksteve.com/enterprise/topic.php/OSD_Multicast_IS_VERY_SLOW/?TopicId=40996&Posts=3 From the 2419357 article above I found the Registry settings for UDPStartPort and UDPEndPort to be off from what was in the GUI. In the Registry these were set to 64001 and 65000 respectively instead of the expected 63001 and 64000 range. I'd changed the Registry to match the GUI and restarted the WDS service and triggered another deployment with no effect. The download of the WIM using Multicast is still taking forever. Already Tried: - Using Unicast we are seeing transfer rates of approx. 12.5MB/sec - Used the MCAST command line tool from Win2K8 ResKit from the Secondary Site to my target client to simulate Multicast traffic and were seeing 5MB/sec - Using SCCM Multicast we are seeing transfer rates to a single client at only 0.125MB/sec (125KBytes/sec)! WTF. Another article I found was: SCCM OSD Multicast - Extremely Slow....Extremely.... http://social.technet.microsoft.com/Forums/en/configmgrosd/thread/77cb45fe-3302-4daa-9ae3-bfcbf2055cd6 I've shared this one with the Networking guy here but he doesn't want to do a restart on the core routers (I wouldn't want to either if I were him). Any other ideas to correct this issue? Help! :) Thanks, -Jeff

Anybody? :)

Have you tried this : http://social.technet.microsoft.com/Forums/en-US/configmgrosd/thread/2a1325d4-0852-4da4-a64d-99fd24d32698

Hi Hanna, The ApBlockSize seemed to do the trick. I tried the TpMaxWindowSize and TpExpWindowSize values first as described at the bottom of that thread but they didn't seem to have any effect. Once I changed the ApBlockSize and restarted the WDS Service speeds are much improved. Now I'll check with the Networking guys to confirm what their MTU size is at the routers and may tweak further, but for now a value of 1385 seems to be working OK. Thanks for your help! -Jeff