I have a Catalyst 9500x Virtual Stack and 2 Routers connected to these Switches.
Router 1 is the Primary Wan link and is connected to Switch 1 (Master) and Router 2 is the Secondary Wan link and is connected to Switch 2.
We have detected that when Switch 1 is reloaded, we have intermitent connectivity lost from WAN networks. It's due to Router 1 LAN (connected to reloaded Catalyst 9500x), goes UP (line and protocol) but Catalyst 9500x is still booting and data plane is not working yet (HSRP and OSPF are not available via LAN interface in the Router).
We have seen 9500x boot process is:
- Interfaces Ethernet goes UP
- Switch detects is a Virtual Stack System and put the interfaces DOWN again.
- Switch putting down interfaces
- Switch putting the interfaces UP again
- Switch finish the boot and all is working again.
We have some ideas in order to solve the issue using routing mechanism (tracking, etc...) but we prefer to understand (and fix if possible) why 9500x is putting interfaces UP before data plane working.
Thanks and regards!
What version are you running? Sounds similar to this issue:
Hope that helps!