Distribution Of Routes Between Pe Routers - Juniper ACX1000 Configuration Manual

Junos os; acx series universal access router

Hide thumbs Also See for ACX1000:

Table of Contents

Distribution of Routes Between PE Routers

Static route

Figure 50 on page 823

illustrates how routes are distributed from CE routers to PE routers.

Router PE1 is connected to two CE routers that are in different VPNs. Therefore, it creates

two VRF tables, one for each VPN. The CE routers announce IPv4 routes. The PE router

installs these routes into two different VRF tables, one for each VPN. Similarly, Router

PE2 creates two VRF tables into which routes are installed from the two directly connected

CE routers. Router PE3 creates one VRF table because it is directly connected to only

Figure 50: Distribution of Routes from CE Routers to PE Routers

VPN A site 1

VPN B site 1

When one PE router receives routes advertised from a directly connected CE router, it

checks the received route against the VRF export policy for that VPN. If it matches, the

route is converted to VPN-IPv4 format—that is, the 8-byte route distinguisher is prepended

to the 4-byte VPN prefix to form a 12-byte VPN-IPv4 address. The route is then tagged

with a route target community. The PE router announces the route in VPN-IPv4 format

to the remote PE routers for use by VRF import policies. The routes are distributed using

IBGP sessions, which are configured in the provider's core network. If the route does not

match, it is not exported to other PE routers, but can still be used locally for routing,

for example, if two CE routers in the same VPN are directly connected to the same PE

The remote PE router places the route into its bgp.l3vpn.0 table if the route passes the

import policy on the IBGP session between the PE routers. At the same time, it checks

the route against the VRF import policy for the VPN. If it matches, the route distinguisher

is removed from the route, and it is placed into the VRF table (the

routing-instance-name.inet.0 table) in IPv4 format.

Chapter 26: Configuring Layer 3 VPNs

VPN A site 2

VPN B site 2

VPN A site 3

Show Quick Links

Table of Contents