Failover Scenarios For Portchannels And Fspf Links - Cisco MDS 9000 Series Configuration Manual

Configuring Fibre Channel Routing Services and Protocols
Figure 47: Fault Tolerant Fabric with Redundant Links
For example, if all links are of equal speed and no PortChannels exist, the FSPF calculates four equal paths
from A to C: A1-E-C, A2-E-C, A3-D-C, and A4-D-C. If PortChannels exist, these paths are reduced to two.

Failover Scenarios for PortChannels and FSPF Links

The SmartBits traffic generator was used to evaluate the scenarios displayed in
Using Traffic Generators, on page
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 (see
• Shutting down the links in either switch 1 or switch 2 (see
Figure 48: Failover Scenario Using Traffic Generators
Table 17: Physically Removing the Cable for the SmartBits Scenario
PortChannel Scenario
Switch 1
110 msec (~2K frame drops)
100 msec (hold time when a signal loss is reported as mandated by the standard)
Table 18: Shutting Down the links in Switch for the SmartBits Scenario
PortChannel Scenario
Switch 1
~0 msec (~8 frame
drops)
No hold time needed
for the SmartBits Scenario , on page
for the SmartBits Scenario , on page
Switch 2
Switch 2
110 msec (~2K frame drops)
Signal loss on switch 1
Failover Scenarios for PortChannels and FSPF Links
187. Two links between switch 1 and switch 2 exist as either equal-cost
187).
187).
FSPF Scenario (Equal cost ISL)
Switch 1
130+ msec (~4k frame drops)
FSPF Scenario (Equal cost ISL)
Switch 1
130+ msec (~4K frame drops)
No hold time needed
Cisco MDS 9000 Series Fabric Configuration Guide, Release 8.x
Figure 48: Failover Scenario
Table 17: Physically Removing the Cable
Table 18: Shutting Down the links in Switch
Switch 2
Switch 2
Signal loss on switch 1
187