Show Nsf - NETGEAR M6100 Series Reference Manual

To prepare the backup management blade in case of a failover, applications on the
management blade continuously checkpoint some state information to the backup blade.
Changes to the running configuration are automatically copied to the backup blade. MAC
addresses stay the same across a nonstop forwarding failover so that neighbors do not have
to relearn them.
When a nonstop forwarding failover occurs, the control plane on the backup blade starts from
a partially-initialized state and applies the checkpointed state information. While the control
plane is initializing, the chassis cannot react to external changes, such as network topology
changes. Once the control plane is fully operational on the new management blade, the
control plane ensures that the hardware state is updated as necessary. Control plane failover
time depends on the size of the chassis, the complexity of the configuration, and the speed of
the CPU.
The management plane restarts when a failover occurs. Management connections must be
reestablished.
For NSF to be effective, adjacent networking devices must not reroute traffic around the
restarting device. NETGEAR Managed Switch software uses three techniques to prevent
traffic from being rerouted:
• A protocol may distribute a part of its control plane to chassis blades so that the protocol
can give the appearance that it is still functional during the restart. Spanning tree and port
channels use this technique.
• A protocol may enlist the cooperation of its neighbors through a technique known as
graceful restart. OSPF uses graceful restart if it is enabled (see
Commands on page 729).
• A protocol may simply restart after the failover if neighbors react slowly enough that they
will not normally detect the outage. The IP multicast routing protocols are a good example
of this behavior.
To take full advantage of nonstop forwarding, layer 2 connections to neighbors should be via
port channels that span two or more chassis slots, and layer 3 routes should be ECMP routes
with next hops via physical ports on two or more slots. The hardware can quickly move traffic
flows from port channel members or ECMP paths on a failed blade to a surviving blade.

show nsf

This command displays global and per-blade information on NSF configuration on the
chassis.
Format
show nsf
Mode Privileged Exec
M6100 Series Switches
Chassis Commands
40
IP Event Dampening