Catalyst 9410 Dual SUPs and Failover

[Ex-Engineer1968]

Hello!

I have a Catalyst 9410 chassis in the ACCESS LAYER - L2 ONLY - with DUAL SUPs. BUT, I only have the DNA Essentials and the Network Essentials licenses, NOT the Advantage license, so that means I do not have some HA functionality like NSF or ISSU. Is that a deal breaker?

What supporting technologies and features MUST be deployed, if any, in a DUAL SUP chassis just to have a failover if the active SUP goes down? In other words, if I have DUAL SUPs, does that mean I MUST configure NSF and SSO to get failover? Or is simply having the DUAL SUPs in the chassis enough to get the failover to work if the active SUP goes down?

[M02@rt37]

Hello @Ex-Engineer1968 

Even without NSF and SSO, dual SUPs will still provide redundancy. If the active SUP fails, the standby SUP will assume the role of the active SUP, but the recovery will not be seamless. Protocols like STP and other L2 processes will need to reconverge...

Without NSF, the forwarding plane will experience downtime during the SUP switchover since NSF allows the forwarding to continue uninterrupted during a control plane failure. Without NSF, when the active SUP fails, packet forwarding will pause while the new SUP becomes active and rebuilds its state.

Note that SSO is part of Network Essentials license... This feature ensures that the control plane state (like routing tables, protocol states, etc.) is fully synchronized between the active and standby SUPs. When the active SUP fails, the standby SUP takes over without having to reinitialize the control plane, resulting in a faster switchover. So you can and should configure it for faster failover with minimal control plane disruption. However (and again), without NSF, packet forwarding will still experience a brief disruption during SUP failover.

[Ex-Engineer1968 · Accepted solution]

This was a fantastic answer because it was complete and addressed exactly what i was asking. Thank you! Are you with Cisco TAC? Just curious. I will eventually accept your answer as the solution, but I just want to see if anyone else wants to chime in first.