NLB across subnets

**aza2004** · 17-12-2008

Ok so here is my dilema. I have two terminal servers on different subnets (different locations). I want to use NLB to load balance traffic and for fail over, applying updates ect. Now the two subnets are connected with two wan switches using static routes.
Here is what I set up

Terminal Server 1:
NIC 1
Host IP address: 172.16.8.9 /21
Gateway: 172.16.15.254
DNS:172.16.16.1/172.16.16.2
NIC 2
Host IP address: 172.16.8.10 /21
Cluster IP address: 172.16.8.15 /21
NLB Mode: Unicast
Port Rule: all opened
Name resolution: Termserver.domain.com
Priority:1
TCP/IP advanced
Additional IP: 172.16.8.15

Terminal server 2
NIC 1
Host IP address: 172.16.16.9 /21
Gateway: 172.16.23.254
DNS:172.16.16.1/172.16.16.2
NIC 2
Host IP address: 172.16.16.10 /21
Cluster IP address: 172.16.8.15 /21
NLB Mode: Unicast
Port Rule: all opened
Name resolution: Termserver.domain.com
Priority: 2
TCP/IP advanced
Additional IP: 172.16.8.15

Now terminal server one appears fine but server two has no network connectivity outside of its subnet.

I tried adding an addition cluster IP 172.16.16.15 /21 assigned this as the cluster ip for server two. Added it as an additional IP on both servers. But then neither server could communicate outside of it subnet. I did kind of expect this.

I then tried removing 172.16.8.15 from server 2 additional IP and 172.16.16.15 from server 1 additional IP. Now both servers could see the entire network (all subnets). But NLB doesn't work as this is now two seperate clusters due to two seperate IP's.

I've always been under the impression this could work but I see no way of making it work. Unless I put both servers on the same site however this kind of defeats the object of load balancing accross the WAN. All help welcome.

Russ Kaufmann · 18-12-2008

"aza2004" <aza2004.3kke3d@DoNotSpam.com> wrote in message
news:aza2004.3kke3d@DoNotSpam.com...
>
> Ok so here is my dilema. I have two terminal servers on different
> subnets (different locations).

NLB nodes need to be in the same subnet. You can use a VLAN that stretches
across the two locations.

--
Russ Kaufmann,
MVP, MCSE: Messaging and Security, MCT, MCITP, MCTS and other stuff

ClusterHelp.com, a Microsoft Certified Gold Partner
Web http://www.clusterhelp.com
Blog http://msmvps.com/clusterhelp

**aza2004** · 18-12-2008

setting up a vlan across two locations isn't feasible here as our wan switches only support physical port based vlans. But thanks for the info, I will put both servers on the same subnet. Come back to this later after we have refresh our network switches.

James Yeomans BSc, MCSE · 19-12-2008

If you want to load balance between 2 servers you could try implementing
Round Robin DNS. You create 2 records with the same name each with a
different ip address and configure your dns server to allow round robin dns.
This will cause the server to alternate the address that it hand out, it is
primitive but should give you an even distribution between your 2 servers:
http://www.justaskjames.co.uk/default.asp?link=139
--
James Yeomans, BSc, MCSE
Ask me directly at: http://www.justaskjames.co.uk

"aza2004" wrote:

>
> setting up a vlan across two locations isn't feasible here as our wan
> switches only support physical port based vlans. But thanks for the
> info, I will put both servers on the same subnet. Come back to this
> later after we have refresh our network switches.
>
>
> --
> aza2004
> ------------------------------------------------------------------------
> aza2004's Profile: http://forums.techarena.in/members/aza2004.htm
> View this thread: http://forums.techarena.in/server-cluster/1089102.htm
>
> http://forums.techarena.in
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>

Russ Kaufmann · 19-12-2008

"James Yeomans BSc, MCSE" <JamesYeomansBScMCSE@discussions.microsoft.com>
wrote in message news:A6A5AD4B-5E8D-494B-8E0B-87C07A860F10@microsoft.com...
> If you want to load balance between 2 servers you could try implementing
> Round Robin DNS.

Round Robin DNS is not a high availability solution. If one server is down,
DNS will continue to refer clients to the down server as a percentage of the
membership in the round robin solution. So, if you have two servers in this
configuration, and one server goes down, half of your clients will be
directed to the down server.

--
Russ Kaufmann,
MVP, MCSE: Messaging and Security, MCT, MCITP, MCTS and other stuff

ClusterHelp.com, a Microsoft Certified Gold Partner
Web http://www.clusterhelp.com
Blog http://msmvps.com/clusterhelp

**aza2004** · 19-12-2008

James I'm with Russ on this I have used round robin before although extremely effective at load balancing. There is no redundancy built in as Russ says clients continue to be directed to a down server. I have now moved the server to the same site and am in the process of setting up NLB. However once our network switches have all been replaced then I will look at the vlan option again.

Thanks for the suggestion and thanks for the help.
Aaron