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@puck.nether.net> wrote: > > > > ---------- Forwarded message ---------- > From: Eli Kagan <e.ka...@yahoo.com> > To: "cisco-nsp@puck.nether.net" <cisco-nsp@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@puck.nether.net> > To: "cisco-nsp@puck.nether.net" <cisco-nsp@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 > _______________________________________________ > cisco-nsp mailing list cisco-nsp@puck.nether.net > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ > _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/