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Tuesday, 6 August 2013

Cisco VIC 1225 with VMware | Redundant Networking Problem

Hi all,

I have been installing some Cisco C220 servers with the VIC 1225 CNA (converged network adapter) for a local company. As part of the installation these servers were connected to a pair of Nexus 5K's with the CNA used for both fiber channel and 10gbps ethernet for VMware ESXi 5.1.

The connectivity was pretty standard to any installation of this type with one 10 gig link going to one switch and the other going to the second switch, exactly like if this was a 1 gig implementation with catalyst switches. So i installed VMware and as part of the default installation vmware takes the first network card and uses that as its management interface and also uses the MAC address of that NIC for the MAC address of the management console. FINE! But that will come back and trouble me later on.

So i give the management interface a static IP address and connect using the vSphere client and all's going well until the point where i add the second NIC, and all connectivity to the host was lost!  So i connect the CIMC and run the test network connectivity and everything fails. So i remove one of the NIC's and everything comes back up again. So after lots and lots of testing and nothing working when everything looked correct, we resulted in logging a support call with Cisco.

It turns out that there is currently a fault on the VIC 1225 where by, even though all the vNIC's are in promiscuous mode, if one port see's the MAC address of another vNIC it doesn't forward the packet. I have been told that there is a fix on the way and should be available in September.

So the solution, if you get this as a problem is to delete the default VMware management interface and create a brand new one, this is given a VMWare MAC address stating in 00 and is therefore not a MAC address that appears on the VIC. Add your two network to this new management interface and everything works as you would expect.

Thanks for reading and i hope this was of use to someone.