Network high availability on exchange using GLBP on cisco switch

Posted on 2010-09-13
Last Modified: 2012-05-10
I am currently leveraging GLBP--gateway load balancing, on my 4948 cisco switches. This gives me the ability to connect 2 Ethernet cables into my servers, one from one switch and one from another. If one switch fails then the server still has a route out using the other link. This works well on everything but exchange. My exchange server has two nics on it and both are configured with a different ip address ( and 104). I have send and receive when both nics are active and I can also send and receive if only the nic with 105 is active. I run into a problem when 105 goes down. I can send out but can not receive on 104, any thought as to why this would be happening? I have checked all firewall settings and everything is fine.
Question by:justin0104
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Tony1044 earned 500 total points
ID: 33670124
Which version of Exchange?

Author Comment

ID: 33672084
Exchange 2010
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Expert Comment

ID: 33672127
Ah ok - are your send/receive connectors bound to a single IP address?
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Expert Comment

ID: 33672148
>I run into a problem when 105 goes down
does the physical interface go down, meaning does the switchport go down/down

> I run into a problem when 105 goes down. I can send out but can not receive on 104, any thought as to why this would be happening?

I imagine it has to do with the switches have stale/outdated/incorrect layer 2 information, and possibly issues relating to multiple default gateways utilizing different metrics. The design you have is not mean to work the way that you think. What you are trying to accomplish is failover but with the wrong technology. You want to look into the concept of NIC Teaming (Bonding, etc).


Author Comment

ID: 33672381
Yeah perferrably I would like to give the server 2 nics team them or whatever and have the same ip address on them so I don't have a problem like this.
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Expert Comment

ID: 33672438
Teaming them is by far the better solution.

Basically you get one virtual network card with a single IP address and a virtual MAC address (which is usually a copy of the first NIC in the team).

I tend to set them as a failover pair only, as more advanced functions can cause issues with things like Exchange.

Once this is done, you can give the virtual NIC a static IP address (if it hasn't taken the one from the first NIC).

If one NIC goes down / cable is unplugged the other seamlessly takes over and Exchange won't even notice.

However - you should really cable one NIC into one switch and the other into another for the best resilience, otherwise if you lose a switch you still lose Exchange.

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