5672UP to 2248 FEX via 40GB breakout

[rgnelson]

We are about to purchase two 5672UP's and two 2248TF-E bundles and I'm having a hard time nailing down the optimum interconnect

In the old 5500 world, we would use the 8 10GB FET modules (4 at the 2K, 4 at the 5K) with  fiber LC connector OM3 cables. 

For the 5600/2K setup, it looks like there is a FET40G option now. the configurator indicates that is 1xFET-40G and 4xFET-10G's using an MTP/MPO to LC breakout cable. 

My question is: Do I want to use the FET's and the fiber cable or do I want to order an SFP+ Copper breakout cable like QSFP-4SFP10G-CU1M? Distance is not an issue, the 5600's and the 2K's will be adjacent. Cost wise, the SFP+ breakout is a little more than the optical breakout.

Is there something else I am missing on using the 40GB ports for interconnecting the 2k's?

[Reza Sharifi · Accepted solution]

If the distance is not an issue, I would use the SFP+ copper breakout cable. The only issue is that the copper SFP is not as flexible as regular fiber, but you should be able to patch and still dress the cables.

Also, the fiber breakout cable is pretty expensive (about $600 per cable).

HTH

[rgnelson]

Further post implementation info for future folks searching. 

The 40Gb ports are an in-chassis module in the 5672's. These modules have 2 modes for the ports, 4x10Gb and native 40Gb. All the ports share the mode, so using these breakout cables forces the module into 4x10Gb mode for all of the ports. 

Its a subtle distinction because of how 40Gb works, but does affect design choices if there are more things to connect to the available ports.