let's assume we have the following scenarios. 2 Cisco Catalyst 6509 having one supervisor engine in each one of them. In case of failure of the first supervisor engine in the first chassis, how long does it take for the 2nd switch to take over ?
Thanks in advance.
if you have one supervisor in each chassis you are looking for node redundancy not supervisor redundancy.
routing protocols convergence time and STP time are involved.
standard STP requires up to 50 seconds to converge unless additional features like uplinkfast and backbonefast are used.
routing protocols convergence time can be as low as 15 seconds with EIGRP and default settings
It can be lowered with specific configuration for example sub-second OSPF hello timers or use of IP BFD (when supported)
Supervisor redundancy means two supervisors in the same device.
With SSO the best redundancy strategy the time is small.
Hope to help