Juniper JUNOSE 11.2.X BGP AND MPLS, Configuration Manual

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Use in the route-target address family to cause a BGP speaker (the local router) to
send the Default-RT-MEM-NLRI route (0:0:0/0) to a peer group for use as a default
route.
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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.
•
If you specify a BGP peer group by using the peerGroupName argument, all the members
of the peer group inherit the characteristic configured with this command. You cannot
override the characteristic for a specific member of the peer group.
•
Outbound policy configured for the neighbor (using the neighbor route-map out
command) is not applied to default routes that are advertised because of the neighbor
default-originate command.
•
This command takes effect immediately.
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Example
host1(config)# router bgp 100
host1(config-router)# router address-family route-target
host1(config-router-af)# neighbor default-originate
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Use the no version to prevent the default route from being advertised by BGP. Use the
default version to remove the explicit configuration from the peer or peer group and
reestablish inheritance of the feature configuration.
•
See neighbor default-originate.
Route Selection When Route-Target Filtering Is Enabled
When route-target filtering is enabled for a peer, BGP applies outbound filters to initially
prevent the speaker from advertising any VPN routes to the peer.
If the BGP speaker subsequently receives a Default-MEM-NLRI route from a peer, BGP
applies outbound filters for the peer to prevent route-target filtering from suppressing
any VPN routes sent to the peer.
BGP follows the standard route selection process to find the route-target filtering best
path for RT-MEM-NLRI routes received from other autonomous systems. The selection
is based on the AS path and other MP-NLRI path-attributes attached to the route.
The route-target membership information, which includes the route target and the
originator AS number, enables BGP speakers to use the standard path selection rules to
remove duplicate, less-preferred paths from the total set of paths to route-target
membership peers.
For RT-MEM-NLRI routes that originated within the local AS and are received from an
IBGP peer, BGP considers the route-target filtering best path to be the set of all available
IBGP paths for the RT-MEM-NLRI prefix. BGP then sets outbound route filters so that
VPN routes that match the route target are sent to all IBGP peers that advertised the
RT-MEM-NLRI route. This behavior does not affect how the BGP speaker in turn advertises
the RT-MEM-NLRI routes.
419 Copyright © 2010, Juniper Networks, Inc.
Chapter 6: Configuring BGP-MPLS Applications