Sizing Fabric Interconnect connection

[mountaineer07]

Dear everyone,

We are sizing Cisco UCS for our new system. We wonder if there is any recommendation for "uplink : downlink" ratio that we should consideration?

Or more generally, is there any best practice to calculate FI's uplink?

Thanks in advance!

Mountaineer07

[Wes Austin]

This document is a good place to start:

http://www.cisco.com/c/en/us/products/collateral/servers-unified-computing/ucs-manager/whitepaper_c11-697337.html

Config Guide:

http://www.cisco.com/c/en/us/support/docs/servers-unified-computing/ucs-6120xp-20-port-fabric-interconnect/110267-ucs-uplink-ethernet-connection.html

Keep in mind that your vEth interfaces are going to pin to and only utilize the number of uplinks you have between your FI and IOM. So if you have 8 servers and only 1 link between IOM and FI, then that link is split 8 ways. It is also best practice to utilize port-channels between FI and IOM, that way your server interfaces pin to a port-channel rather than an individual link. In the event you lose a link, no re-pinning occurs or disruption to OS, if you had to replace a cable, SFP, etc.

Same scenario going from FI to northbound network. Typically you deploy at least 2-4 Uplink interfaces per FI, but if you are a smaller environment, you may only require 1-2.