WIndows Server with Multiple IP addresses in different VLANS

Unanswered Question
Aug 4th, 2009

Hello Everyone,

we have a Windows 2008 server that has a primary and secondary IP address on it. Each IP address actually belongs to a different VLAN. The NIC is a virtual NIC from 2 teamed NICs. The server team put routers on the server to allow it to reach whicc ever VLANs the traffic was destined for. To try and make this work on the network side we put the switchport into trunk mode and allowed all needed VLANS. The server cannot talk to anything but itself now. Was this the right way to go on this?

Thanks in advance! All replies rated.

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Peter Paluch Tue, 08/04/2009 - 08:18


From the switch viewpoint, you have done it correctly - the port must be a trunk.

However, you have to somehow configure the Windows to use 802.1Q frame tagging. I am not skilled in Windows networking but I assume that simply teaming two NICs on Windows does not make them work as a 802.1Q tagging NIC. Therefore, the server team should actually look for options how to define VLANs on the virtual NIC, how to turn on the 802.1Q frame tagging and how to assign IP addresses to individual VLANs.

Best regards,


Marvin Rhoads Tue, 08/04/2009 - 09:44

Is your server team trying to do both Network Load Balancing (NLB) and VLAN tagging? If so, that probably won't work because, according to Microsoft, "You cannot enable 802.1Q VLAN tagging and integrated NLB on the same interface of a network adapter. This limitation is imposed by NLB."

Without teaming, they can just assign a separate IP address to each NIC and the network team put them in their respective VLANs (with associated default gateways).

The network adapter vendor may add functionality, typically added via their drivers' configuration tools.

Hope this helps.


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