Stacking Dell PowerConnect 7000 Series Switches
NSF Example 1
Assume Unit 1 is the stack manager and Unit 2 is the standby switch. The following scenarios illustrate how the network recovers when Unit 1 is powered down.
•With NSF disabled: Unit 2 takes over as manager with a cold restart and clears the hardware tables. The video stream stops on Hosts 2 and 3 for at least 30 seconds as the OSPF adjacency is rebuilt, multicast routes are relearned, and spanning tree reconverges.
•With NSF enabled: Unit 2 takes over as manager with a warm restart. OSPF graceful restart keeps the adjacency with Router 1 up and Router 1 continues to forward to the stack. There is no perceivable outage of the video stream through the stack.
NSF Example 2:
Assume Unit 2 is the stack manager and Unit 3 is the standby switch, and both ports are active on the LAG. In this scenario, NSF is enabled and the initiate failover command is used.
•Because the unit with the root port goes down, the stack stops forwarding until the spanning tree control plane comes back and places the link on Unit 3 in the forwarding state (about 3 seconds).
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