We are running several 4500-X VSS setups and we would like to upgrade them from 3.4.x to 3.6.x. Cisco states that ISSU is not supported due to incompatible software changes. So I asked TAC if it was possible to do an upgrade while keeping only layer 2 traffic active. TAC suggested the following upgrade procedure:
- Copy the image on both the switches [bootflash: <image name>
- Configure the config-reg 0x2102
- Reload the stanby switch and it will boot from new image [3.6.4]
- Check the redundancy state, standby will show Standby cold
- Then, you can do a force switch over
Has anyone tried this? Will this keep layer 2 active during the upgrade?
TAC also claims that multichassis etherchannels *should* remain active. Can anyone verify this?