Juniper JUNOSE, Руководство по настройке

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If you issue the neighbor default-originate command, BGP sends the default route
to that neighbor regardless of whether the default route exists in the IP forwarding
table.
In Figure 15 on page 56, router NY originates the default route 0.0.0.0/0 to router
Albany only. Router Chicago does not receive the default route.
Figure 15: Advertising a Default Route
To configure router NY:
host1(config)# router bgp 200
host1(config-router)# network 192.168.42.0 mask 255.255.254.0
host1(config-router)# neighbor 10.3.3.1 remote-as 300
host1(config-router)# neighbor 192.168.10.2 remote-as 100
host1(config-router)# neighbor 192.168.10.2 default-originate
You can also specify a route map to modify the attributes of the default route. If the
default route does not match the route map, then the default route is not advertised.
Redistributing Default Routes
By default, the redistribute command does not permit a default route to be
redistributed into BGP. You can use the default-information originate command to
override this behavior and permit the redistribution of default routes into BGP.
default-information originate
■
Use to enable the redistribution of default routes into BGP.
■
Use the route-map keyword to specify outbound route maps to apply to the
default route. The route map can modify the attributes of the default route.
■
This command takes effect immediately. However, if the contents of the route
map specified with this command change, the new route map may or may not
take effect immediately. If the
disable-dynamic-redistribute command has
been configured, you must issue the clear ip bgp redistribution command to
apply the changed route map.
■
Outbound policy configured for the neighbor (using the neighbor route-map
out command) is applied to default routes that are advertised because of the
default-information originate command.
56 ■
Advertising Routes
JUNOSe 11.0.x BGP and MPLS Configuration Guide