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NLB issue with TMG 2010 SP1 Update 1 Enterprise Array on 2008 R2 VM's

We have had the following problem when applying Update 1 to 2 x TMG 2010 SP1 array members:

After installing the update and re-booting the array member (AM) the 1st AM that returns seems to work OK (servicing external requests on the listeners and can ping external IP addresses) but as soon as the 2nd AM comes on-line the 1st AM stops servicing requests externally and has no external connectivity. As soon as the 2nd AM is powered down or re-booted the 1st AM starts working normally again!

I will try my best to explain the configuration but if I miss anything then please don't hesitate to ask!!


ESX 4.0.0 208167 (Update 1) Cluster with multiple HP BL460c G6 Blades.

Enterprise with a single vCenter server (virtual)

2 x 2008 R2 Standard x64 running TMG 2010 SP1 in an Enterprise Array

Unicast NLB cluster

Notify switches (switch level) set to 'NO'

VMXNET3 Nic's on the guests.


Removed Update 1 - didn’t resolve the issue.

Disabled and re-enabled External NIC – didn’t resolve the issue.

Removed the 1st AM from the Array. Checked external connectivity and everything was OK. Re-added the AM to the array and immediately hit the same problem.

Tried removing VIP’s and re-adding but same problem.


The workaround in the end was to go to the advanced settings on the NIC (within windows) and set the MAC address to ‘not present’. This disables and re-enables the NIC and both nodes started working again!

We then re-installed Update 1 to see if it would cause the same problem and as soon as they were re-booted the problem re-occurred. We used the above workaround to resolve the problem.

Any idea’s??

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3 Replies

As for NLB in my setup I'm using  multicast and also VMware suggests that you should use multicast with NLB. Hope you did solve your problem!

best regards, Stoz

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I also would liketo know more info about how did you go with your 2x TMG2010 VM deployment ?

are you using VMware HA or justtwo normal VMware VM but utilizing the Multicast NLB

/* Please feel free to provide any comments or input you may have. */
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I was also facing same kind of problem ...it's related routing issue check ur routing table n add another network route in TMG Network Route.

and Keep in mind only one External Gateway allow to ping External DNS and due to it's add for default route in TMG.

if u think i m exactlly getting you, so plz send TMG 2010 Network Symentric

i am waiting............

Kuver Pratap Singh Virtualization Consultant
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