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Can we use the two NICs in MCS for dual-homing for redundancy?


I would like to find out the purpose of having two NICs in MCS, is it for dual-homing to two switches for redundancy? Is Yes, does it mean that the two NICs share the same IP Address and one is in active mode and the other in passive mode?

If no, what is the real purpose of having two NICs?

Hope you can provide some information on this.



Cisco Employee

Re: Can we use the two NICs in MCS for dual-homing for redundanc

NIC teaming has recently been certified for use with CallManager (as of OS 2000.2.4). This is teaming only - no separate IP addresses. The app note is here:

In addition, as reported by those who tested the teaming, there are some design considerations:

- If you connect the NICs to two spearate switches, you must span the VLAN between the two switches as teaming requires the NIC’s to be in the same L2 domain. This has considerations as to best-practices (spanning vlans between switches) as well as speed of convergence in event of failure (STP tweaking)

- Beware if you are doing port security - the same MAC and IP address can appear on two different switches

- Redundancy should be addressed to make sure that a link failure does not put each NIC in a separate broadcast domain (HP/Compaq recommendation as well).

Check the app note as NIC teaming is not supported on all servers shipped with dual nics. The dual nics are a result of using industry-standard platforms. Support came after testing and documentation.

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