Cisco Nexus

Mon Feb 2 19:09:22 UTC 2015

I think it depends on what the upstream product from the FEX is and what
your requirements are. Last I checked,  eVPC was not supported on the N7K,
but it was supported as an option on the N5K platform.  eVPC being the dual
homed FEX to two a pair of N7K's running a VPC cluster. I know this is an
old post, but here's a good one that explains precisely what I mean:

If you look at the N5K verified scalability guide, you see this:

Maximum FEXs dual homed to a vPC Cisco Nexus 5500 Series Switch Pair: 24

http://www.cisco.com/en/US/docs/switches/datacenter/nexus5500/sw/configuration_limits/b_N5500_Config_Limits_602N11_chapter_01.html

If you look at the N7K verified scalability guide, there is *no* mention of
dual-homed fex architectures:

http://www.cisco.com/en/US/docs/switches/datacenter/sw/verified_scalability/b_Cisco_Nexus_7000_Series_NX-OS_Verified_Scalability_Guide.html#reference_E1ED6266546C444093CC27DEB0E1B38E

If I'm wrong and someone is dual homing 2K FEXs to 7K VPC pairs, please
correct me.

If you're interested in latency numbers fex-to-fex, here are some numbers
provided to me by our SE:

http://jumboframe.net/jumboframe/2013/5/5/n2k-fex-to-fex-latency-and-a-reader-follow-up
<http://static1.squarespace.com/static/513c6d36e4b0cc0702f94292/t/51866c97e4b0580e000cf5bd/1367764121313/fex-to-fex-latency.jpg?format=750w>

As you can see, these numbers are decent, but you'd have to be very careful
in choosing your FEX model if you're looking for better than average store
and forward performance out of your FEX.

On Mon, Feb 2, 2015 at 10:17 AM, Herman, Anthony <
Anthony.Herman at mattersight.com> wrote:

> Nanog,
>
> I would like to poll the collective for experiences both positive and
> negative with the Nexus line. More specifically I am interested in hearing
> about FEX with N2K at the ToR and if this has indeed made any impact on
> Opex as well as non-obvious shortcomings to using the fabric extenders.
> Also if anyone is using any of the Nexus line for I/O convergence (FCoE) I
> would be interested in hearing your experience with this as well.
>
> Thank you in advance,
>
> -A
>