Windows 2008 NLB issue

Windows 2008 security on NLB causes issues with pings from other subnets and connectivity. Run:
netsh interface ipv4 set interface NLB weakhostsend=enable
(where NLB) is the name of the adapter.


Windows 2008 introduces a "strong host model" that doesn't allow the
different NICs to talk to each other. For example, if a request comes in on
the 2nd NIC and there's no default gateway setup, then the NIC will not use
the 1st NIC to reply to the requests. (even though there's a default gateway
setup on that 1st NIC).

In order to change that behaviour and go back to a 2003 model, you go to the
command prompt and then you type:

netsh interface ipv4 set interface NLB weakhostreceive=enable
netsh interface ipv4 set interface NLB weakhostsend=enable

(where NLB is the name of the network interface... default is Local Area
Connection)

As an alternative, you can set a default gateway on the 2nd NIC but that can
introduce more problems where the system doesn't know which way to send
traffic. MS said that I could set the metric to 2 on the 2nd NIC and that
way it will only be used if the 1st NIC is unavailable.

http://technet.microsoft.com/en-us/magazine/2007.09.cableguy.aspx

Unquote:

netsh interface ipv4 set interface NLB weakhostreceive=enable
netsh interface ipv4 set interface NLB weakhostsend=enable