Configuring A Default Route; Advertising Default Routes - Juniper BGP - CONFIGURATION GUIDE V 11.1.X Configuration Manual

NOTE: This default behavior does not apply to VPN routes. Redistribution of IBGP
routes (routes received from an internal BGP peer) in a VRF is always enabled. You
do not have to issue this command to enable redistribution of internal BGP routes
in a VRF.
bgp redistribute-internal

Configuring a Default Route

Default routes can provide backup routes if primary connections fail or if the route
information for a destination is unknown. A router uses the default route in its IP
forwarding table to route traffic toward a destination for which no routing entry
exists. The accepted BGP convention is to represent a default route by the network
prefix 0.0.0.0/0.

Advertising Default Routes

If you want a router to serve as a default destination for traffic from other routers
that do not know where to forward traffic, you can configure the router to advertise
a default route. Use the neighbor default-originate command to specify the neighbors
to which this router will advertise the default route. Said another way, these neighbors
will dynamically learn the default route from the router you configure.
Use to enable the redistribution of IBGP routes in addition to EBGP routes into
IGPs configured for BGP route redistribution.
Redistribution of IBGP routes is disabled by default, except within a VRF where
IBGP routes are always redistributed.
You must clear all BGP sessions after issuing this command for it to take effect.
Example
host1(config-router)#bgp redistribute-internal
host1(config-router)#exit
host1(config)#exit
host1(config)#clear ip bgp *
All IBGP and EBGP routes subsequently placed in the IP routing table are
redistributed to IGPs that have route redistribution enabled.
To authorize redistribution of routes that are already present in the IP routing
table, you must use the clear ip bgp * command (this command will bounce
the BGP sessions) or the clear ip routes * command to reinstall BGP routes in
the IP routing table.
Use the no version to restore the default of permitting the redistribution only of
EBGP routes.
See bgp redistribute-internal.
Chapter 1: Configuring BGP Routing
Advertising Routes
55