[c-nsp] Problem with Microsoft NLB on Server 2008 running in Multicast mode

[Bracey, John]

Youssef & Community:

No, the patch mentioned in KB960916 did NOT fix the issue for us (even though it's specifically supposed to).  In fact it has introduced some instability; now when our server admin switches between NLB clustering methods (unicast, multicast, igmp multicast) the server will bluescreen and reboot.  It's not consistent every time, but this behavior did not happen prior to the application of the patch.

We asked our tech support person this morning exactly what this patch does, because it certainly didn't fix the issue it was supposed to fix.  The only answer we could get was that it updated the nlb.sys file to a newer version.  

Microsoft's "solution" (we have a case open with them on this issue) is exactly the one mentioned in the techblog article, to create all the static ARP and MAC Address entries (which many of you have done).  They continue to place blame on the routing/switching even when the KB articles say that Microsoft is aware of this issue.  We're not comfortable with that solution as it no doubt will lead to confusion down the road that may be difficult to troubleshoot.

So, at this point I think we've decided to resolve the issue by backing out this patch, moving the cluster to its own separate vlan, leave the cluster in unicast mode, and call it a day.  

I thank you all for your feedback on this issue, it helped our decision process a bunch.

Thanks.

- John Bracey


-----Original Message-----
From: Asbjorn Hojmark - Lists [mailto:lists at hojmark.org] 
Sent: Thursday, March 25, 2010 1:12 PM
To: Peter Rathlev
Cc: Bracey, John; 'cisco-nsp at puck.nether.net'
Subject: Re: [c-nsp] Problem with Microsoft NLB on Server 2008 running in Multicast mode

On Thu, 25 Mar 2010 20:01:55 +0100, you wrote:

> C6k(config)# arp vrf X 10.0.0.1 03bf.0abc.def0 ARPA

If it is in fact a 6500, that alone is a pretty bad idea, as traffic
bound for the cluster will be process-switched. It is recommended to
add at static MAC entry as well.

 mac-address-table static 03bf.0abc.def0 vlan X int Y disable-snoop

-A