Juniper JUNOSE 11.2.X BGP AND MPLS, Руководство по настройке

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When BGP selects a RT-MEM-NLRI route from a peer as the best path for the
RT-MEM-NLRI prefix, BGP modifies the outbound filters to enable the speaker to advertise
to that peer all VPN routes that correspond to that route target. These filters affect the
subsequent calculation of the peer's Adj-RIBs-Out entries.
EBGP confederation peers are treated as IBGP peers when the BGP speaker is selecting
the route-target filtering best path. When the BGP speaker advertises routes, then the
EBGP confederation peers are treated normally, as EBGP peers.
You can control the maximum number of received EBGP best paths that are considered
for path selection. The
external-paths command limits external route target membership,
thus controlling the number of EBGP peers that receive the route target VPN routes
referenced by the RT-MEM-NLRI route. BGP ignores routes received from the peer after
the limit specified with the
external paths command is reached.
Configuring Route-Target Filtering
To configure route-target filtering:
1.
Enable the BGP routing process in the specified AS.
The AS number identifies the PE router to other BGP routers.
host1(config)# router bgp 738
2.
Configure the peers for the BGP speaker. Use neighbor commands to specify the PE
router peers to which BGP advertises routes and to configure any additional BGP
attributes.
host1(config-router)# neighbor 10.2.2.2 remote-as 45
host1(config-router)# neighbor 10.2.2.2 update-source loopback 0
host1(config-router)# neighbor 10.2.2.2 next-hop-self
3.
Create the route-target address family to configure the router to use BGP signaling
to exchange the RT-MEM-NLRI attribute with peer routers.
Optionally, you can use the signaling keyword with the address-family command
when you configure the route-target address family to specify BGP signaling of
reachability information. Currently, you can omit the
signaling keyword with no
adverse effects.
host1(config-router)# address-family route-target signaling
4.
Activate the neighbors that routes of the route-target address family are exchanged
with for this BGP session. The neighbors must first be created in the default IPv4
unicast address family.
host1(config-router-af)# neighbor 10.2.2.2 activate
host1(config-router-af)# neighbor 10.2.2.2 next-hop-self
5.
(Optional) Configure BGP to send a Default-MEM-NLRI route for all peers in the
address family or for a specific peer or peer group in the address family.
host1(config-router-af)# default-information originate
or
host1(config-router-af)#
neighbor 10.2.2.2 default-originate
Copyright © 2010, Juniper Networks, Inc. 420
JunosE 11.2.x BGP and MPLS Configuration Guide