Brocade BigIron RX Series Configuration Guide - Manual (Page 922)

844 BigIron RX Series Configuration Guide
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Enabling fast external fallover
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BigIron RX(config-bgp)# enforce-first-as
Syntax: [no] enforce-first-as
Neighbor local-AS
The Neighbor Local Autonomous System (AS) allows a router that is a member of one AS to appear
to also be a member of another AS. This feature is useful, for example, if Company A purchases
Company B, but Company B does not want to modify its peering configurations.
This feature can only be used for true EBGP peers. When establishing a BGP connection, the router
will use the configured neighbor local AS, instead of the system AS number.
For example, if you want a router to use AS 200, instead of 100 when peering with neighbor
11.11.11.2, enter commands such as the following.
BigIron RX(config)#router bgp
BigIron RX(config-bgp-router)#local-as 100
BigIron RX(config-bgp-router)#graceful-restart restart-time 30
BigIron RX(config-bgp-router)#graceful-restart
BigIron RX(config-bgp-router)#neighbor 11.11.11.2 remote-as 101
BigIron RX(config-bgp-router)#neighbor 11.11.11.2 local-as 200
Syntax: [no] neighbor <ip-address> local-as <local-as-number>
Enter the IP address of the neighbor with which the device will be peering for <ip-address>.
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 or the TCP connection fails 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.
NOTE
The fast external fallover feature applies only to directly attached EBGP neighbors. The feature does
not apply to IBGP neighbors.
To enable fast external fallover, enter the following command.
BigIron RX(config-bgp)# fast-external-fallover
To disable fast external fallover again, enter the following command.
BigIron RX(config-bgp)# no fast-external-fallover
Syntax: [no] fast-external-fallover