The BGP multiprotocol extensions (MP-BGP) enable BGP to support IPv4 services
such as BGP multicast and BGP/MPLS virtual private networks (VPNs). BGP/MPLS
VPNs are sometimes known as RFC 2547bis VPNs. Some of the applications for
which you might use BGP/MPLS VPNs are to transport packets across an IP backbone,
enable overlapping VPNs, operate inter-AS VPNs, enable multicast across VPNs, and
provide carrier-of-carriers VPNs.
Address Families
The BGP multiprotocol extensions specify that BGP can exchange information within
different types of address families. The JUNOSe BGP implementation defines the
following different types of address families:
■ Unicast IPv4—If you do not explicitly specify the address family, the router is
configured to exchange unicast IPv4 addresses by default. You can also configure
the router to exchange unicast IPv4 routes in a specified VRF.
■ Multicast IPv4—If you specify the multicast IPv4 address family, you can use
BGP to exchange routing information about how to reach a multicast source
instead of a unicast destination. For information about BGP multicasting
commands, see “Configuring BGP Routing” on page 3. For a general description
of IPv4 multicasting, see IPv4 Multicast Overview in the JUNOSe Multicast Routing
Configuration Guide.
■ VPN IPv4—If you specify the VPN-IPv4 (also known as VPNv4) address family,
you can configure the router to provide IPv4 VPN services over an MPLS
backbone. These VPNs are often referred to as BGP/MPLS VPNs.
■ Unicast IPv6—If you specify the IPv6 unicast address family, you can configure
the router to exchange unicast IPv6 routes or unicast IPv6 routes in a specified
VRF. For a description of IPv6, see IPv6 Overview in the JUNOSe IP, IPv6, and IGP
Configuration Guide.
■ Multicast IPv6—If you specify the multicast IPv6 address family, you can use
BGP to exchange routing information about how to reach an IPv6 multicast
source instead of an IPv6 unicast destination. For a general description of IPv6
multicasting, see IPv4 Multicast Overview in the JUNOSe Multicast Routing
Configuration Guide.
■ VPN IPv6—If you specify the VPN-IPv6 address family, you can configure the
router to provide IPv6 VPN services over an MPLS backbone. These VPNs are
often referred to as BGP/MPLS VPNs.
■ L2VPN—If you specify the L2VPN address family, you can configure the PE router
for VPLS L2VPNs or VPWS L2VPNs to exchange layer 2 network layer reachability
information (NLRI) for all VPLS or VPWS instances. Optionally, you can use the
signaling keyword with the address-family command for the L2VPN address
family to specify BGP signaling of L2VPN reachability information. Currently,
you can omit the signaling keyword with no adverse effects. For a description
of VPLS, see “Configuring VPLS” on page 589. For a description of VPWS, see
“Configuring VPWS” on page 657.
■ Route-target—If you specify the route-target address family, you can configure
the router to exchange route-target membership information to limit the number
of routes redistributed among members. For a description of route-target filtering,
see “Constraining Route Distribution with Route-Target Filtering” on page 410.
380 ■ Overview
JUNOSe 11.1.x BGP and MPLS Configuration Guide
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