Upgrading the VSF stack software

Upgrading the software on a VSF stack consists of two basic steps:

  1. Copy the new software image into primary or secondary bank in flash.
  2. Reboot the stack with new image. See vsf sequenced-reboot

FSU differs from the normal software upgrade in the second step where only the standby of the VSF stack boots, using the upgraded image. The current commander is intact, thus ensuring that the IMs and their ports on commander switch are still available for traffic.

Following is the sequence used by FSU:
  1. The user downloads new firmware into the primary or secondary bank and issues the CLI command to perform FSU.

  2. The standby switch reboots to the new firmware and boots up as a commander switch.

  3. The old commander switch reboots to the new firmware when the VSF link is brought up and joins the other switch as a new standby.

  4. Traffic starts passing through the new commander as it comes up. However, the switchover is not stateful. L2 traffic is guaranteed to be within the timeline of 3 secs but not L3.