I've seen several implementations of "interface vlan <id>" on many Catalyst switches for interVLAN routing but on a single instance of a core switch only.
Recently, I've seen 2 core switches connected with each other via HSRP and with interface vlan <id> configured on each switches -- same vlan id created for both switches. The interface vlan <id> was configured to have a virtual ip and a priority id for HSRP.
My question is, in these kind of scenario, what would be the reason, chances or cause that a virtual interface (layer 3 - switch virtual interface) would go into a down state ? I am just looking for a clear answer/picture since it's the physical interface that often encounter these type of problems most of the time.