[c-nsp] Cisco Cat4500 Quad Sup VSS ISSU IOS Upgrade

[Eli Kagan]

Thanks Garrett!

Unfortunately I cannot afford a 30 minutes outage.

What doesn't make sense to me is the "issu loadversion" step. If I understand correctly, it would load the current hot standby with the new version. But wouldn't a cold standby take over if I reloaded the hot standby CPU, effectively bringing me back to the same state?

Is there a reason why I shouldn't do the upgrade the old fashion way? That is, change the boot variable, reload hot standby manually, failover and then reload the other three supervisor engines. 
I mean, is there a benefit to using "issu loadverion/runversion/acceptversion/commitversion" process vs just loading the software and reloading manually?

Thanks,
Eli 






On Friday, March 12, 2021, 04:08:25 PM EST, Garrett Skjelstad <garrett at skjelstad.org> wrote: 





I know this is an awful answer, but just don't do ISSU on them. 😅

Most of my experiences come from quad Sup8s in the same chassis. We have been running 3.11.1 for the past 49 weeks, since our last cycle, which is 12/18 months.

The biggest ISSUe (lol) with it, is just the sheer number of jumps back and forth as you climb the ISSU ladder from a historic release. We have also found it to be beneficial to do a pre-ISSU supervisor restarts for each supervisor prior to actually doing the upgrade so as to lessen the chance of getting 'stuck' in a ISSU-loop with a hung Supervisor. The fact that 4500 sups sit in a 'cold' mode when doing the jumps just adds to the delay, 6500s/6800s are MUCH nicer for this action in the fact they are 'warm(hot?)' and already booted.

A full cold restart of the shelves takes approximately 23 minutes per our lab units. We have found in some locations that have tolerable maintenance windows, to load/prep and simply cold start the shelves, instead of a weeklong of ISSU maintenance windows. Of course, if you patch every 60-120 days as the cadence of each release, perhaps it's more manageable. I read there are some additional protections and time optimizations in later rommon versions, but for our use, we just haven't seen the need for a seperate out of cycle ROMMON patches. We are currently looking at simply replacing them with Catalyst 9k models.

The 4500-Xs run the same supervisor set and are just as friendly, although contending with only duals vs quads.

Obviously out-of-band management on all supervisors is a necessity.

YMMV, good luck!
-Garrett

On Fri, Mar 12, 2021 at 12:27 PM Eli Kagan via cisco-nsp <cisco-nsp at puck.nether.net> wrote:
> 
> 
> 
> ---------- Forwarded message ----------
> From: Eli Kagan <e.kagan at yahoo.com>
> To: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
> Cc: 
> Bcc: 
> Date: Fri, 12 Mar 2021 20:25:01 +0000 (UTC)
> Subject: Cisco Cat4500 Quad Sup VSS ISSU IOS Upgrade
> Hi all,
> 
> I have a rather old Cat4507R+E pair, running on four Sup7e as a VSS, IOS-XE version 3.8.8E.
> 
> I'd like to understand what's the right way of doing an ISSU on a quad sup system. I am planing to go to version 3.8.10E unless someone has a better suggestion.
>  
> Sharing your first hand experience would be greatly appreciated.
>  
> Thanks,
> Eli
> 
> 
> 
> ---------- Forwarded message ----------
> From: Eli Kagan via cisco-nsp <cisco-nsp at puck.nether.net>
> To: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
> Cc: 
> Bcc: 
> Date: Fri, 12 Mar 2021 20:25:01 +0000 (UTC)
> Subject: [c-nsp] Cisco Cat4500 Quad Sup VSS ISSU IOS Upgrade
> 
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