Dell 7000 Series - page 31

Stacking Dell PowerConnect 7000 Series Switches
Page 29
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 co ntinues to forward to the
stack. There is no perceivable outage of the video stream through the sta ck.
NSF Example 2:
Assume Unit 2 is the stack manager and Unit 3 is the standby switch, and bot h 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 s tops forwarding until the
spanning tree control plane comes back and places the link o n Unit 3 in the forwarding
state (about 3 seconds).