Connecting Cisco UCS 6120 FI directly to Cisco Catalyst 6500?

[wider]

I look at a lot of design guide with Cisco UCS solution and everywhere there is Cisco Nexus 5000/7000 switches connection to uplink ports of Cisco UCS 6120 FI with advantages of vPC technology.

How about to connect Cisco UCS 6120 FI directly to 10GE ports of Cisco Catalyst 6500 (without VSS and with VSS)? It is possible by design?

If I use C6500VSS there will be port-channel from UCS aggregation all Nx10GE bandwidth?

And what if I use C6500 (without VSS) - how it will be about many links from UCS to two C6500 boxes? It will be blocked by STP? Somewhat else?

Please explain me, because we have only C6500 switches in our data center and want to test one Cisco UCS schassis.

[Jeremy Waldrop · Accepted solution]

Yes, you can connect the 6120s to cat6500s with or without VSS. With VSS you get a vPC like port channel where 2 links from a single 6120 can be connected to 2 different 6500s in an LACP port channel.

VSS is not required, you can connect 1 or more 10G/1G uplinks from a 6120 to cat6500s. I you have 2 cat6500s (non-vss) and 2 uplinks per 6120 then you will want to connect 1 to cat6500-1 and the other to cat6500-2. I would recommend going ahaed and creating a single port port-channel so that you can easily add uplinks in the furture without downtime.

Ideally for non-vss I would have 4 10G uplinks per 6120; 2 in a port-channel to cat6500-1 and 2 in a port-channel in cat6500-2

[wider]

Jeremy, thanks a lot for quick reply. Can you give me a few links to cisco.com documentation where I could find design Cisco UCS without Nexus platform?

[jomartin · Accepted solution]

Hi. This is correct. All our documentation and design guides have examples with Nexus 5000 or Neus 7000, but this has more to do with our strategy than what is supported. Unfortunately we don't have guides for each single switch that we sell, but that doesn't mean that they are not supported. The Fabric Interconnect uses 802.1q and/or LACP (both standards) to communicate to the upstream devices. As long as the uplink port connect to a switch that can do them, you'll be fine.

Many customer don't have Nexus 5K or Nexus 7K in their environments and they have successfully deployed UCS. Connection to Cat6k (with or without VSS), Cat 4k or even our stackable units are all valid. Cisco would definitely prefer that you use our switches, but if you have competitos switches you should also have no problem connecting to them. As long as they comply to standards, it will be fine.

It is also good to point out that 10GE connection is recommended for the obvious performance benefit, but it is not necessary. The first 8 ports of a 6120 can be configured for 1GE as well as the first 16 ports of a 6140. Please be aware that there is an open issue with this (CSCtn94464), but it has been supported since day one.

As for the STP concerns... If you use the Fabric Interconnects in its default (end-host mode) configuration, there is no STP to worry about. The connections from the LAN side will always be forwarding. The UCS will take care of looks by implementing Deja-vu and RPF checks.