Configuring A Default Route; Advertising Default Routes - Juniper JUNOSE 11.2.X BGP AND MPLS Configuration Manual

bgp redistribute-internal

Configuring a Default Route

Copyright © 2010, Juniper Networks, Inc.
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.
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.
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.
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.
Chapter 1: Configuring BGP Routing
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