The limit for number of vPCs for a pair of Nexus 31108PC-V

[onyXMaster]

Hi!

The data sheet for Nexus 3100-V states that the number of supported EtherChannels is 64 (with vPC).

Unfortunately, the Verified Scalability Guide for these switches states that "Number of switch port EtherChannels"is only 10 and does not discuss the effect of vPC on this.

We based our network design and purchase decision on the data sheet, not on the scalability guide (I guess this was an oversight on our end, and an expensive one).

The switches didn't arrive yet (and so the service contract is not active, so I can't ask the TAC), but I fear the worst, since our design involves at least 25 2-port 10G vPCs being available.

I wonder what is the source of this contradiction between Cisco documentation, maybe I'm missing something here? Could anyone guide me on this topic?

Thank you.

[chrihussey]

Hello,

Take a close look at the footnotes for the Tables of the Verified Scalability Guide. It indicates these as being limitations if all the listed features are running at the same time vs being tested on an isolated basis. That being said, depending on your requirements you could be OK.

Hoe this helps

[onyXMaster]

Thank you for responding.

Unfortunately the wording of the footnotes is vague at best. The value 10 that I'm referring to is in the "Verified Maximum" column, which is is described as "Indicates the maximum scale capability tested for the corresponding feature individually. This number is the absolute maximum currently supported for the corresponding feature. If the hardware is capable of a higher scale, future software releases may increase this verified maximum limit."
Then definition of "supported" isn't very clear to me in this case, and the hardware limitations or the availability of more than 10 port-channels/vPCs are still unknown to me. While I find it strange that Cisco would design a 48-port switch with vPC support and limit the amount of vPCs to 10, I've seen such limitations before (on 36xx Catalysts).

I'd expect someone from Cisco to respond, but well, this is not a real support channel, so I can only hope for it and wait for the real hardware to test it myself.

P.S. I wonder what TAC would tell to me if I ask them for 64 vPCs as advertised in datasheet =)

[chrihussey]

You raise a valid point. I did some additional research and checked the latest versions of code and it doesn't to appear to have changed.

This probably isn't much of a help, but if you do run into an issue, possibly using something like a C3850-24X-S aggregation switch pair could in a stack configuration to offset the port-channel limitation. I'm not aware of any port-channel restrictions and you could have regular port-channels to the 3850 and then connect the 3850 via vPC to the 31108.

Regards  

[onyXMaster · Accepted solution]

It appears that "verified scalability" is that as it's named -- verified scalability. We were able to create 40 vPCs easily, with software limit set to 511. So it may or may not work, it works in our case.

[chrihussey]

Good to hear. Thanks for the update and votes.