Reloading CSM

Unanswered Question
Jun 4th, 2008


I have CSM with 4.2(4) code running in Catalyst 6509 chassis (and nother one - standby - in Catalyst 6513 chassis). Both chassis have Sup720 with 12.2(18)SXD7 code (a bit old code)

I had heard some "rumors" that rebooting CSM only (not the entire switch) can distabilize the switch and might need the entire switch reboot.

I wanted to ask if anyone had any experience with rebooting CSM in similar environment (code levels) and had run into issues where entire switch needed to be rebooted afterwards.

Thanks a lot!


I have this problem too.
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Gilles Dufour Thu, 06/05/2008 - 07:52


I do constant CSM reboot in my lab when testing different configs, versions, ... and never had a n issue on the switch resulting from such operation.

The only issue I heard about is that the CSM could freeze for switch bus for a short period causing data loss - but it was never confirmed as far as I can tell.


dknov Thu, 06/05/2008 - 12:00


When you say freeze for switch bus, do you mean that CSM's 4Gb connection to DBUS becomes frozen?

If so, thinking about it, I am trying to see what can go wrong.... The one thing that comes to my mind is that both CSMs can end up Active and this when it can become messy as far as ARP table of upstream router and MAC address table of the switches where CSMs are....

I see that all VIPs configured on CSMs are shown as one MAC in both ARP table of upstream router and MAC tables of switches where CSMs are installed.

Is this a virtual MAC, or does Active CSM generate Gratitous ARPs on switchover between them?

If it is virtual MAC, how do switches learn it? Does CSM originate traffic with this virtual MAC being Source MAC (like HSRP does)?



Gilles Dufour Thu, 06/05/2008 - 12:34


again, I have NEVER seen an issue and I do a few reloads everyday.

What I heard - but never got the proof - is that people have seen the DBUS freeze so it wasn't usable by any module - not jsut csm - for a short period (like 2 or 3 sec) resulting in data loss.

This was never proven and no data was ever collected.

Personally I think it is perfectly safe to reload a CSM module.


CSCO10199329 Thu, 06/05/2008 - 08:05


I've got a couple of 6509's. Both have Sup720 with 12.2(18)SXF6 and CSM modules with 4.2(5).

A couple of times I have rebooted the standby CSM using "no power enable module 1" and "power enable module 1". So far no issues have been noticed.


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