UCS VM-FEX Port Profile Max Ports

[brandonbittinger]

Hello, 

I am in the process of configuring VM-FEX in our UCS environment with VMWare 6.0.I am making Port Profiles and one of the fields in Max Ports. The default for this field is 64 and the only information I can find on this field is that the max ports is 4096.

What exactly is this field? I am assuming this is the number of ports on the DVS that VM's can connect to. is this per host or a total number of ports presented to all hosts? is this number dependent on anything? I think I saw one reference somewhere to there being some form of formula to calculate what this field should be set too. 

Also is this number related to the type of VICs we have and the number of vNICs they support? we are using VIC1240's witch should support 256 vNICs and all blades are also equipped with the UCS Port Expander Card.

Any help is appreciated. Thanks!

[Brandon Rumer (Cisco) · Accepted solution]

Based on my reading this 4096 is the limitation of dynamic ports per VMware host. It makes sense that Cisco would hard-program that into UCS so that you wouldn't get yourself into trouble. This 4096 would apply no matter the VIC combination installed in the server as (I believe) it is an OS addressing limitation. It is interesting that the port-profiles carry the same limitation with no regard to whether its applied to 1 host or 10.

One thing to keep in mind is that VMWare has announced end of support for 3rd party switches, to include VM-FEX (starting after 6.1U1). Implementing VM-FEX now could get you into trouble later. With that said, Cisco and other vendors have 'workarounds' but it wouldn't surprise me if Cisco let VM-FEX die.
https://kb.vmware.com/s/article/2149722

Hope this helps at least bit,
Brandon

[brandonbittinger]

Thank you for the helpful reply. Also thank you for the details about VMWare ending support, I did not realize that. I guess I will just let that dream die. This is such a shame, this is such a neat and underutilized technology.