CUCM NIC Teaming different switches

Unanswered Question
Dec 30th, 2009

We have a dual core network. All access and distribution switches have dual uplinks to the core switches. One uplink port will be blocked by STP at any given time. Can you configure NIC Teaming on CUCM 7.x and above and configure one NIC in one switch and the other NIC in the redundant switch or do both NIC’s need to be in the same switch?

I have this problem too.
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rob.huffman Wed, 12/30/2009 - 08:52

Hi Bill,

Yes, this is the supported/desired config for NIC Teaming as long

as the connected Switchports on the two switches are on the same VLAN.

"NIC Teaming for Network Fault Tolerance

The NIC teaming feature allows a server to be connected to the Ethernet via two NICs and, therefore, two cables. NIC teaming prevents network downtime by transferring the workload from the failed port to the working port. NIC teaming cannot be used for load balancing or increasing the interface speed.

Hewlett-Packard server platforms with dual Ethernet network interface cards can support NIC teaming for Network Fault Tolerance with Cisco Unified CM 5.0(1) or later releases.

IBM server platforms with dual Ethernet network interface cards can support NIC teaming for Network Fault Tolerance with Cisco Unified CM 6.1(2) and later releases. "

And the command to do that as per the CUCM OS CLI Reference Guide is:

"set network failover

This command enables and disables Network Fault Tolerance on the Media Convergence Server network interface card.

Command Syntax

failover {enable | disable}


enable enables Network Fault Tolerance.

disable disables Network Fault Tolerance.


Command privilege level: 1

Allowed during upgrade: No "

The referenced guides:



Cheers buddy!


Bill19795_2 Wed, 12/30/2009 - 11:29

Actually the SRND guide does not specifically say you  can place  the NIC teaming in diffrent switches.

NIC Teaming can be performed with two different switches.

Eth0 can be patched to Switch A

Eth1 can be patched to Switch B

Our current environment consists of two different switches feeding to two different core 6509, redundant links, fiber and over an Opti-man.

Different power runs, different power sources.

NIC Teaming would even work in the same switch. But, what are the odds of one or both ports going bad in the same switch. Not likely.

The odds of one switch going down, maybe. Both switches going down, not likely.

Aaron Harrison Fri, 04/02/2010 - 05:23


Well - the chances of one or two ports going down on one switch are much much higher than the chance of two ports on different switches going down for any number of reasons - administrative error, software/hardware failure, power loss, etc etc.

One switch will have ONLY it's REDUNDANT uplink blocked by STP. It will have connectivity as much as the other.

Generally speaking you would not bother enabling it if you only had one switch to connect to. If you have such a simple topology you probably have a low total port count in the room the server is in, and you probably wouldn't want to waste your sparse resources port to protect against administrative error and a cable failure failure.

The only types of fault tolerance that require linking to the same switch are those that support bandwidth aggregation/load balancing technologies, these aren't supported, and aren't available from the CLI.




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