•
When the Type field is 2, the Administrator subfield occupies four bytes, the Assigned number
subfield occupies two bytes, and the RD format is 32-bit AS number:16-bit user-defined number,
where the minimum value of the AS number is 65536. For example, 65536:1.
To guarantee global uniqueness for a VPN-IPv4 address, do not set the Administrator subfield to any
private AS number or private IP address.
R oute target attribute
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MPLS L3VPN uses route target community attributes to control the advertisement of VPN routing
information. A VPN instance on a PE supports the following types of route target attributes:
•
Export target attribute—A PE sets the export 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 received
from other PEs. If the export target attribute matches the import target attribute of a VPN
instance, the PE adds the routes to the routing table of the VPN instance.
Route target attributes define which sites can receive VPN-IPv4 routes, and from which sites a PE
can receive routes.
Like RDs, route target attributes can be one 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.
MCE overview
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The Multi-VPN Instance CE (MCE) feature allows you to create multiple VPN instances on a CE. The
VPN instances each have an independent routing table and an address space to achieve service
isolation.
As shown in
private routes to the routing tables of corresponding VPN instances.
•
Route exchange between MCE and VPN site—Create VPN instances VPN 1 and VPN 2 on
the MCE. Bind VLAN-interface 2 to VPN 1, and VLAN-interface 3 to VPN 2. The MCE adds a
received route to the routing table of the VPN instance that is bound to the receiving interface.
•
Route exchange between MCE and PE—The MCE connects to PE 1 through a trunk link that
permits VLAN 2 and VLAN 3. On PE 1, create VPN instances VPN 1 and VPN 2. Bind
VLAN-interface 2 to VPN 1, and VLAN-interface 3 to VPN 2. The MCE and PE add a received
route to the routing table of the VPN instance that is bound to the receiving interface.
F igure
94, the MCE exchanges private routes with VPN sites and PE 1, and adds the
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