The Junos OS uses the following routing tables for VPNs:
•
bgp.l3vpn.0—Stores all VPN-IPv4 unicast routes received from other PE routers. (This
table does not store routes received from directly connected CE routers.) This table is
present only on PE routers.
When a PE router receives a route from another PE router, it places the route into its
bgp.l3vpn.0 routing table. The route is resolved using the information in the inet.3 routing
table. The resultant route is converted into IPv4 format and redistributed to all
routing-instance-name.inet.0 routing tables on the PE router if it matches the VRF import
policy.
The bgp.l3vpn.0 table is also used to resolve routes over the MPLS tunnels that connect
the PE routers. These routes are stored in the inet.3 routing table. PE-to-PE router
connectivity must exist in inet.3 (not just in inet.0) for VPN routes to be resolved properly.
When a router is advertising non-local VPN-IPv4 unicast routes and the router is a
route reflector or is performing external peering, the VPN-IPv4 unicast routes are
automatically exported into the VPN routing table (bgp.l3vpn.0). This enables the
router to perform path selection and advertise from the bgp.l3vpn.0 routing table.
To determine whether to add a route to the bgp.l3vpn.0 routing table, the Junos OS
checks it against the VRF instance import policies for all the VPNs configured on the
PE router. If the VPN-IPv4 route matches one of the policies, it is added to the
bgp.l3vpn.0 routing table. To display the routes in the bgp.l3vpn.0 routing table, use
the show route table bgp.l3vpn.0 command.
•
routing-instance-name.inet.0—Stores all unicast IPv4 routes received from directly
connected CE routers in a routing instance (that is, in a single VPN) and all explicitly
configured static routes in the routing instance. This is the VRF table and is present
only on PE routers. For example, for a routing instance named VPN-A, the routing table
for that instance is named VPN-A.inet.0.
When a CE router advertises to a PE router, the PE router places the route into the
corresponding routing-instance-name.inet.0 routing table and advertises the route to
other PE routers if it passes a VRF export policy. Among other things, this policy tags
the route with the route distinguisher (route target) that corresponds to the VPN site
to which the CE belongs. A label is also allocated and distributed with the route. The
bgp.l3vpn.0 routing table is not involved in this process.
The routing-instance-name.inet.0 table also stores routes announced by a remote
PE router that match the VRF import policy for that VPN. The remote PE router
redistributed these routes from its bgp.l3vpn.0 table.
Routes are not redistributed from the routing-instance-name.inet.0 table to the
bgp.l3vpn.0 table; they are directly advertised to other PE routers.
For each routing-instance-name.inet.0 routing table, one forwarding table is maintained
in the router’s Packet Forwarding Engine. This table is maintained in addition to the
forwarding tables that correspond to the router’s inet.0 and mpls.0 routing tables. As
with the inet.0 and mpls.0 routing tables, the best routes from the
routing-instance-name.inet.0 routing table are placed into the forwarding table.
Copyright © 2017, Juniper Networks, Inc.820
ACX Series Universal Access Router Configuration Guide
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