WB1 7.48 BGP Default Routing

7.48 BGP Default Routing
• Configure R2 to originate a default route to R3 and R5 via BGP.
• This default route should be withdrawn if R2's link to BB2 goes down.
 
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You may inject a default route into BGP by using the

network 0.0.0.0 mask 0.0.0.0

command, provided that there is a default route in the RIB. However, this will advertise the default route to all BGP neighbors.

To selectively generate a default route, use the command

neighbor <IP> default-originate [route-map <CONDITION>]

Without the route-map parameter, this command will generate a default route and send it to the configured peer. It is not required to have a matching default route in the BGP table or the RIB.

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R2:
ip prefix-list LINK_TO_BB2 permit 192.10.1.0/24
!
route-map DEFAULT permit 10
 match ip address prefix-list LINK_TO_BB2
!
router bgp 200
 neighbor 155.1.23.3 default-originate route-map DEFAULT
 neighbor 155.1.0.5 default-originate route-map DEFAULT