ICMP and Microsoft Network Load Balancing (NLB)
Problem:
NLB does not balance ICMP by default.Solution:
NLB works great with ICMP (after a simple registry change):HKEY_LOCAL_MACHINE
\System
\CurrentControlSet
\services
\WLBS
\Parameters
\Interface
\{GUID}
\FilterICMP
Change the value from 0 to 1. NLB will balance ping requests like a champ!
Backgroud:
Conventional wisdom holds that Microsoft Network Load Balancer (NLB)only works with TCP and UDP traffic. Indeed, ICMP requests return replies from multiple sources by default.Backgroud:
Obscure URL on Technet has an interesting tid-bit: http://technet.microsoft.com/en-us/library/cc709622(v=ws.10).aspx
Apparently Windows System Image Manger can enable ICMP load balancing "ICMPFilteringEnabled" -but only for new installations.
What about our existing load??
I sent the URL to talented programmer and sys-admin, SAK, who quickly found the necessary registry attribute.