Disable TCP Offloading (Network Steve Forum)

Disable TCP Offloading

Hello forum readers, Any advise on the following will be much appreciated. I have a customer who needs to disable all of the offloading capabilities in the NICs (NOT only the OS) on every machine within his network (XP, 2003, 2008 etc). Are there any ideas? We have found an msdn article posted at http://msdn.microsoft.com/en-us/library/aa938424.aspx that helped cust. to detect a registry hive with those keys but we dont know, if that can really configure the NIC HLM\SYSTEM\CurrentControlSet\Control\Class {4D36E972-E325-11CE-BFC1-08002BE10318}\0009 Changing the values in that hive, and then disable / enable the NIC will it configure it? Can method 2 posted at http://support.microsoft.com/kb/888750 disable offloading on all NICs too? (It seems the best solution. Easy & one move only). Thanks in advance for your time and support Rgds, Nick.

October 23rd, 2009 5:16pm

Dakaroni, I was working the Microsoft Networking team's phone queues when the SNP pack first came out with 2003 SP2. I cannot tell you how many problems were solved by following the steps now listed in method 2 of http://support.microsoft.com/kb/888750. If you want to stop ALL offloading functions this is the best way to go, and it works fantastically. The only headache comes from teaming software, which tries to manage these functions separately. If you have a server with teaming enabled, in addition to setting the registry key you will also very likely need to go about disabling these function in the team. Truly though I would suggest getting rid of teaming altogether: http://cbfive.com/blog/post/Considering-Network-Teaming.aspx Don't forget to give credit where credit is duel vote this as helpful if it helped you.

Free Windows Admin Tool Kit Click here and download it now

October 24th, 2009 2:08am

Dear Jared, Thanks for your time and response. Also found KB Articles below subjected Disabling TCP chimney, but I don't know how much apply on this case: http://support.microsoft.com/kb/948496/ http://support.microsoft.com/kb/949234 This only disables TCP offloading on the OS level. There is no way to automate the process on the NIC itself, since different vendors give different names for TCP offloading. Unless you are using the same vendor for your NICs on every machine What do you think? Rgds, Nick.

October 26th, 2009 12:28pm

Jared, One more thing. Cust. needs to disable it on both levels: OS & NIC! [Fyi, Customer NICs are from Broadcom and Intel]. To me, there is still need to clarify if changing the registry settings of a NIC you actually configure it. I cant find any information on this If we can configure the NICs from the registry, then I suppose we must do it programmatically because If I remember correctly every NIC has its own unique key.. Rgds, Nick.

Free Windows Admin Tool Kit Click here and download it now

October 26th, 2009 3:10pm

Hi Nick,You could refer to the following Kb article to disableTCP Chimney Offload in the OS and on the network adapterInformation about the TCP Chimney Offload, Receive Side Scaling, and Network Direct Memory Access features in Windows Server 2008http://support.microsoft.com/kb/951037Hope this helps.

October 26th, 2009 4:35pm

Free Windows Admin Tool Kit Click here and download it now

October 26th, 2009 5:52pm

The KB article includes the netsh commands. Surely you could scipt them.Bill

October 27th, 2009 3:07am

Dakoroni, Using the DisableTaskOffload key disables everything including the NIC offloading, TCP Chimney, and the whole lot. It quite literally only leaves teaming as the final thing to ensure is turned off. To be clear though, even in the cases where teaming is enabled, and the DisableTaskOffload registry key is set, offloading will not occur, but teaming will break network communications as it tries to offload, even though you told the OS not to, so ensuring that teaming is disabled in those cases is about making sure that things do not break. You can automatethe setting of the DisableTaskOffload registry keyby creating a custom GPO that sets this registry value. Here is a link for creating a custom GPO for search providers, but the generic steps still apply. http://support.microsoft.com/kb/918238/ One bit of caution here is that in MANY cases offloading is a really good thing. You can gain up to a 27% spike in network performance using a suite of offloading functions in windows (See Scalable Networking Pack). You will lose all these functions by turning this off through this registry key so typically I only turn this off on a case by case basis. I have never done this in a wide spread fashion myself, and would not advise setting this on a global level, but obviously you are more in tune on what your customer needs. Don't forget to give credit where credit is due, vote this as helpful if it helped you.

Free Windows Admin Tool Kit Click here and download it now

October 27th, 2009 11:00pm

Thanks Jared for your valuable clarifications, regarding NIC offloading and Teaming.

October 28th, 2009 3:52pm

Talked with customer. At least for Broadcoms BACS, as we can see it doesnt care about offloading but well check it further Is there any info about Cisco devices? Do they need some configuration to support it??? Rgds, Nick.

Free Windows Admin Tool Kit Click here and download it now

October 29th, 2009 3:42pm

Dakoroni, No there is nothing that needs to be done on the network hardware to support enabling or disabling TCP offloading. TCP offloading encompasses a suite of functions that enable the hardware (The NIC)to do some of the processing work when recieving/forming network packets. The packets on the wire though are always the same and need to be to be able to work with other networked devices, so the network devices should need no changes to support this either way. In fact it is common to have differing Offloading functions enabled on each server, depending upon what their NIC cards and OS settings will support.Don't forget to give credit where credit is due, vote this as helpful if it helped you.

October 29th, 2009 4:15pm

Thanks once more for your clarifications. Now the picture is much more clear :) Rgds, Nick.

Free Windows Admin Tool Kit Click here and download it now

October 29th, 2009 7:42pm

This topic is archived. No further replies will be accepted.