TCP/IP offload for Contact Centre Windows servers

[mabooth]

Here is the collated recommendations for Windows 2003 SP2 servers if they are part of a Contact Centre deployment.

• NIC Device driver updated to latest version
  
• KB948496 downloaded and installed and server rebooted
  
• Disable RSS and TCP Offload in the network adapter driver, with these steps:
  
  • Click Start, click Run, type ncpa.cpl, and then click OK.
    
  • Right-click a network adapter object, and then click Properties.
    
  • Click Configure, and then click the Advanced tab.
    
  • In the Property list, click Receive Side Scaling, click Disable in the Value list, and then click OK.
    
  • In the Property list, click TCP/IP Offload (IPv4 Checksum Offload), click Disable in the Value list, and then click OK.
    
  • Repeat steps for Public and Private interfaces.
    
• Check the registry to confirm settings applied after KB patch
  

• HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
  
• EnableTCPChimney = 0
  
• EnableRSS = 0
  
• EnableTCPA = 0
  

• Add the following key in the registry to globally disable TCP Offload
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
    
  • New dword DisableTaskOffload = 1
    
• Reboot the server again and check settings in TCP
  

This has shown to provide a significant improvment in buffering and latency issues across private network links.

For Windows 2008, please check the following link for TCP offload settings.

http://support.microsoft.com/kb/951037

[geoff]

If you are using an HP ProLiant server (DL380 etc), it is preferred to disable this with the HP Network Utility. This gives you access to disable one more property - the Offload Engine - that you cannot reach through properties on the Network Adapter. The others, as mentioned above, also are accessible to be turned off.

When finished, click the Save button and it will reset the adapter. You can do this over VNC and it will drop the link but you can come right back in.

A good command line call to check that you have disabled TCP offload is the following:

netsh int ip show offload

This should produce virtually no output under a heading like 'Offload Options for interface "Local Area Connection" with index: 2:"

No reboot required.

Regards,

Geoff

[dchumbley]

I'm wondering if IPv4 Large Send Offload needs disabled too?  I've got a recurring MDS issue at one customer and all of the above changes have been implemented for some time but we are still getting occasional MDS Delay messages.  When I use the netsh command above it doesn't return anything but I've been researching the Large Send Offload and that seems like it should be disabled too.  Just wondering if anyone else has disable this as well?  Thanks

[digitalhaus]

+1

Should I disable everything that has the word "offload" in it?

[bruce.masters]

Quick question. Did you ever get the MDS issue resolved?  We too are experiencing numerous MDS Sync delay messages when talking to our B side via the WAN. We receive up to 100 a day and have CAD failovers occur.

[Yankovskyi]

Good day!

We have done this recommendations for Windows 2003 SP2 servers and had a problem.

After disable TCP/IP Offload (IPv4 Checksum Offload) we cannot access to RoggerA through RDP.Also we cannot hear port 3389 to RoggerA.

After our investigation we found out that the problem was in RDP settings, because we also deleted NIC teaming and RDP was related to this.

I