392
•
Export target attribute: A local PE sets this type of route target attribute for VPN-IPv4 routes learned
from directly connected sites before advertising them to other PEs.
•
Import target attribute: A PE checks the export target attribute of VPN-IPv4 routes advertised by
other PEs. If the export target attribute matches the import target attribute of the VPN instance, the
PE adds the routes to the VPN routing table.
In other words, route target attributes define which sites can receive VPN-IPv4 routes, and from which
sites that a PE can receive routes.
Similar to RDs, route target attributes can be of the following formats:
•
16-bit AS number
:
32-bit user-defined number
. For example, 100:1.
•
32-bit IPv4 address
:
16-bit user-defined number
. For example, 172.1.1.1:1.
•
32-bit AS number
:
16-bit user-defined number
, where the minimum value of the AS number is 65536.
For example, 65536:1.
Multi-VPN-instance CE
Using tunnels, MPLS L3VPN implements private network data transmission over the public network.
However, the traditional MPLS L3VPN architecture requires each VPN instance exclusively use a CE to
connect with a PE, as shown in
For better services and higher security, a private network is usually divided into multiple VPNs to isolate
services. To meet these requirements, you can configure a CE for each VPN, which increases users’
device expenses and maintenance costs. Or, you can configure multiple VPNs to use the same CE and
the same routing table, which sacrifices data security.
Using the Multi-VPN-Instance CE (MCE) function of the switch, you can remove the contradiction of low
cost and high security in multi-VPN networks. With MCE configured, a CE can bind each VPN in a
network with a VLAN interface on the CE, and create and maintain a separate routing table (multi-VRF)
for each VPN. This separates the forwarding paths of packets of different VPNs and, in conjunction with
the PE, can correctly advertise the routes of each VPN to the peer PE, ensuring the normal transmission
of VPN packets over the public network.
How MCE works
shows how an MCE maintains the routing entries of multiple VPNs and how an MCE
exchanges VPN routes with PEs.
