PowerConnect B-Series FCX Configuration Guide 1005
53-1002266-01
Optional configuration tasks
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For each keyword, <num> indicates the number of seconds. The Keep Alive Time can be 0 through
65535. The Hold Time can be 0 or 3 through 65535 (1 and 2 are not allowed). If you set the Hold
Time to 0, the router waits indefinitely for messages from a neighbor without concluding that the
neighbor is dead.
Changing the BGP4 next-hop update timer
By default, the Layer 3 Switch updates its BGP4 next-hop tables and affected BGP4 routes five
seconds after IGP route changes. You can change the update timer to a value from 1 through 30
seconds.
To change the BGP4 update timer value, enter a command such as the following at the BGP
configuration level of the CLI.
PowerConnect(config-bgp-router)#update-time 15
This command changes the update timer to 15 seconds.
Syntax: [no] update-time <secs>
The <secs> parameter specifies the number of seconds and can be from 1 through 30. The default
is 5.
Enabling fast external fallover
BGP4 routers rely on KEEPALIVE and UPDATE messages from neighbors to signify that the
neighbors are alive. For BGP4 neighbors that are two or more hops away, such messages are the
only indication that the BGP4 protocol has concerning the alive state of the neighbors. As a result,
if a neighbor dies, the router will wait until the Hold Time expires before concluding that the
neighbor is dead and closing its BGP4 session and TCP connection with the neighbor.
The router waits for the Hold Time to expire before ending the connection to a directly-attached
BGP4 neighbor that dies.
For directly attached neighbors, the router immediately senses loss of a connection to the neighbor
from a change of state of the port or interface that connects the router to its neighbor. For directly
attached EBGP neighbors, the router can use this information to immediately close the BGP4
session and TCP connection to locally attached neighbors that die.
The fast external fallover feature applies only to directly attached EBGP neighbors. The feature does
not apply to IBGP neighbors.
If you want to enable the router to immediately close the BGP4 session and TCP connection to
locally attached neighbors that die, use either of the following methods.
To enable fast external fallover, enter the following command.
PowerConnect(config-bgp-router)#fast-external-fallover
To disable fast external fallover again, enter the following command.
PowerConnect(config-bgp-router)#no fast-external-fallover
Syntax: [no] fast-external-fallover
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