Tech Blog: mixing media types on a Cisco UCS IOM Module connected to a Fabric Interconnect

JUL 22, 2013

Today’s Tech Blog comes from Jeff Wyant and Kevin Martin in the form of a question:
Can you mixed media types on a Cisco UCS IOM Module connected to a Fabric Interconnect?

interesting questions came out of a planning meeting for a new installation of a pair of Cisco UCS blade systems and fabric interconnects. Can you mix media types from the IOM modules in the chassis to the Fabric Interconnects. Mixing a twinax cable with a traditional SFP and fiber cable. This situation arose from a challenging datacenter layout with the desire to separate across the isles the two chassis and FIs but keep cabling cost down.  Most of the UCS system installs I have been involved are using twinax cables because it’s cost is substantially cheaper than traditional SFPs and fiber cables.  When distance becomes an issue between the chassis and the FIs, we use SPFs and fiber cables.

Having never deployed in this configuration, I quickly turned to online resources looking a validated answer. After searching for an hour and discussing with other engineers, we had nothing. Still needing an answer, we decided to experiment in our lab.  We have a running FlexPod lab environment in our office, connected using twinax cables.  So we launched vCenter and UCSM, keeping an eye on connectivity, port group states, and signs of packet loss. I removed one twinax cable and replaced it with an SPF adapter and fiber cable on both the IOM module in the chassis and on the Fabric Interconnect.  Sure enough, the port group and trunk re-established itself without intervention and we didn’t experience any packet loss.

Once again our Trace3 FlexPod lab had proven to be invaluable in helping us test and validate configurations for our clients. So the answer is Yes, you can mix media types in IOM modules:

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