> # Failover Scenarios for PortChannels and FSPF Links

> The SmartBits traffic generator was used to evaluate the scenarios displayed . Two links between switch 1 and switch 2 exist as either equal-cost ISLs or PortChannels. There is one flow from traffic generator 1 to traffic generator 2. The traffic was tested at 100 percent utilization at 1 Gbps in two scenarios:

> - Disabling the traffic link by physically removing the cable.
> - Shutting down either switch 1 or switch 2 .

> Table 23-3 Physically Removing the Cable for the SmartBits Scenario
> PortChannel Scenario | FSPF Scenario (Equal cost ISL)
> --- | ---
> Switch 1 | Switch 2 | Switch 1 | Switch 2
> 110 msec (~2K frame drops) | 130+ msec (~4k frame drops)
> 100 msec (hold time when a signal loss is reported as mandated by the standard)

> Table 23-4 Shutting Down the Switch for the SmartBits Scenario
> PortChannel Scenario | FSPF Scenario (Equal cost ISL)
> --- | ---
> Switch 1 | Switch 2 | Switch 1 | Switch 2
> ~0 msec (~8 frame drops) | 110 msec (~2K frame drops) | 130+ msec (~4K frame drops)
> No hold time needed | Signal loss on switch 1 | No hold time needed | Signal loss on switch 1

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