Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 606)

576 Multi-Service IronWare Switching Configuration Guide
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VSRP fast start
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• Once a VSRP restart port is brought up by a VSRP instance, other VSRP instances (in Master
state) that have this port as a member do not go to forwarding immediately. This is a safety
measure that is required to prevent transitory loops. This could happen if a peer VSRP node
gets completely cut off from this node and assumed Master state. In this case, where there are
2 VSRP instances that are in Master state and forwarding, the port comes up and starts
forwarding immediately. This would cause a forwarding loop. To avoid this, the VSRP instance
delays forwarding.
Recommendations for configuring VSRP fast start
The following recommendations apply to configurations where multiple VSRP instances are running
between peer devices sharing the same set of ports:
• Multiple VSRP instances configured on the same ports can cause VSRP instances to be
completely cut off from peer VSRP instances. This can cause VSRP instances to toggle back
and forth between master and backup mode. For this reason, we recommend that you
configure VSRP fast start on a per port basis rather than for the entire VLAN.
• We recommend that VSRP peers have a directly connected port without VSRP fast start
enabled on it. This allows protocol control packets to be received and sent even if other ports
between the master and standby are down.
• The VSRP restart time should be configured based on the type of connecting device since
some devices can take a long time to bring a port up or down (as long as several seconds). In
order to ensure that the port restart is registered by neighboring device, the restart time may
need to be changed to a value higher than the default value of 1 second.
Configuring VSRP fast start
The VSRP fast start feature can be enabled on a VSRP-configured device, either on the VLAN to
which the VRID of the VSRP-configured device belongs (globally) or on a port that belongs to the
VRID.
To globally configure a VSRP-configured device to shut down its ports when a failover occurs, then
restart after five seconds, enter the following command.
Brocade(configure)# vlan 100
Brocade(configure-vlan-100)# vsrp vrid 1
Brocade(configure-vlan-100-vrid-1)# restart-ports 5
Syntax: [no] restart-ports seconds
This command shuts down all the ports that belong to the VLAN when a failover occurs. All the
ports will have the specified VRID.
To configure a single port on a VSRP-configured device to shut down when a failover occurs, then
restart after a period of time, enter the following command.
Brocade(configure)# interface ethernet 1/1
Brocade(configure-if-1/1)# vsrp restart-port 5
Syntax: [no] vsrp restart-port seconds
In both commands, the seconds parameter instructs the VSRP Master to shut down its port for the
specified number of seconds before it starts back up. Enter a value between 1 – 120 seconds. The
default is 1 second.