Figure 94: Bgp/Mpls Vpn Eibgp Example - Juniper BGP - CONFIGURATION GUIDE V 11.1.X Configuration Manual

JUNOSe 11.1.x BGP and MPLS Configuration Guide

Figure 94: BGP/MPLS VPN EIBGP Example

VRF A has two paths to get to CE 2: the IBGP path through the MPLS network, and
the EBGP path by means of regular IP.
To support BGP/MPLS ECMP, PE 1 is configured with the maximum-paths eibgp
command in the IPv4 unicast VRF A address family. Doing this allows both the EBGP
paths from CE 2 and the IBGP paths from PE 2 to be selected as multipaths in the
VRF A routing information base (RIB) for use in load balancing.
Traffic taking the various routes from CE 1 to CE 2 is treated as follows:
maximum-paths
442
Configuring BGP VPN Services
Traffic from CE 1 to CE 2 that takes the EBGP route from PE 1 is forwarded as
IP packets.
Traffic from CE 1 to CE 2 that takes the IBGP route from PE 1 is forwarded as
MPLS-encapsulated packets. PE 2 receives the MPLS-encapsulated traffic from
PE 1, removes the encapsulation, and then forwards the traffic as IP packets by
means of the EBGP route to CE 2.
Use to enable ECMP support for BGP/MPLS VPNs.
Specify a value in the range 1–16; the default value is 1. The value indicates the
maximum number of equal-cost multipaths for VPN routes.
This command takes effect immediately; it does not bounce the session.
For BGP/MPLS support, you must specify the maximum number of equal-cost
multipaths in the context of a VRF IPv4 unicast or IPv6 unicast address family.
This command is not supported for the VPNv4 or VPNv6 address families.
The maximum-paths eibgp command cannot be used if the router is currently
configured with the maximum-paths or maximum-paths ibgp command.
Example
host1(config)#router bgp 100
host1(config-router)#address-family ipv4 vrf vrfA
host1(config-router-af)#maximum-paths eibgp 6