[c-nsp] Nexus 5xxx VPC peer keepalives

[Tony Varriale]

----- Original Message ----- 
From: "Church, Charles" <Charles.Church at harris.com>
To: "nsp-cisco" <cisco-nsp at puck.nether.net>
Sent: Wednesday, April 28, 2010 12:35 PM
Subject: [c-nsp] Nexus 5xxx VPC peer keepalives


> Anyone,
>
> Coming up on a design issue with our upcoming first deployment of Nexus 
> 5010s and 5020s in a new datacenter.   It's recommended in the following 
> doc to use the mgmt0 interface for peer keepalive messages:
>
> http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/layer2/Cisco_Nexus_5000_Series_NX-OS__chapter8.html#concept_47F7274E5FDA489884D0488BC491B066
>
> We're doing a true out of band management approach on this new network, so 
> the mgmt0 interfaces all home back to an OOB switch/router (4507)  which 
> houses the NMS gear, etc.  My concern is that a reload (or failure of some 
> type) on this OOB switch could cause a 'dual active' situation on all the 
> Nexus pairs of devices .  (6 pairs of 5010s, and the pair of 5020s that 
> aggregate the 5010 pairs).  I don't think I want that to happen.  So the 
> alternative seems to be a back to back non-VPC-peer link between the two 
> devices using a VLAN interface, but I hate the idea of using a 10 gig port 
> just for keepalives.  There are what appears to be additional copper mgmt 
> ports on the boxes, but they're covered up, and not in the CLI.  Any way 
> to utilize those?  Any other possibilities I'm overlooking?  Or am I stuck 
> getting 1 gig copper SFPs and crossover cables for keepalives?
>
> Thanks,
>
> Chuck

There are specific rules and actions that are taken when specific failures 
occur and it's important to understand them.  Also, if this is your first go 
at this, I would highly recommend testing the scenarios so you can get 
comfortable.  Part of the value in Nexus is the vPC.  Unless you have a very 
specific reason that is broken by the vPC, get comfortable with it.  The 
dual active scenario isn't that bad.

Oddly enough, I was testing a 350mbps multicast stream in a similiar 
environment today.  2 5ks that were dual active - workstation on a single 
attached 2k.  The keepalive link was down between those 5ks and had 
connection to network via peer link only.  The 2nd 5k had only 1 uplink to 
7k-1.  The source of the multicast was on a 2k hanging off 7k-2 and a 
separate set of 5ks.

All multicast packets were received and in order (reliable multicast testing 
with sequencing).

tv