4900M Upgrade "stacked"

[dazza007]

Hi

I have 2 4900M which do not have stacking capabilites and have been configured using a fibre cable for intercore connectivity. 

I am looking to upgrade the ios on them, however i am nervous as i the cores do not have a traditional setup for vlans as in a stack. In that a vlan on core 1 has an address and a standby ip. The same vlan on core 2 has a different ip address and the same standby. 

When upgrading would i need to upgrade on core 1 then let it talk to eachother and upgrade core 2 or just do them in tandem and let the 2 core switches come back up. Would having a non-traditional stacking mechanism cause extra delay in the upgrade process?

Many Thanks

Darren

[Giuseppe Larosa]

Hello @dazza007 ,

you can upgrade each switch in different times on client Vlans the HSRP protocol will move the VIP address and active role to the switch that is not rebooting in 10 seconds (3 missed HSRP hellos).

When core1 comes back on line it will take over if preemption is configured on each standby group and its priority is higher.

Later you can upgrade core2.

For safety you should ask for a maintenance window of two hours.

Hope to help

Giuseppe