HP Intelligent Management Center Licenses - Manual (Page 36)

RD (Route Distinguisher)
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You are recommended to configure a distinct RD for each VPN instance on a PE, guaranteeing
that routes to the same CE use the same RD. The VPN-IPv4 address with an RD of 0 is in fact
a globally unique IPv4 address. RD code format is as follows: Type: two bytes. Value: six
bytes. An RD can be in either of the following two formats distinguished by the Type field:
1. When the value of the Type field is 0, the Administrator subfield occupies two bytes, the
Assigned number subfield occupies four bytes, and the RD format is: 16-bit AS number:32-bit
user-defined number. For example, 100:1.
2. When the value of the Type field is 1, the Administrator subfield occupies four bytes, the
Assigned number subfield occupies two bytes, and the RD format is: 32-bit IPv4 address:16-bit
user-defined number. For example, 172.1.1.1:1.
For the global uniqueness of an RD, you are not recommended to set the Administrator subfield to
any private AS number or private IP address.
VPN target attributes
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MPLS L3VPN uses the BGP extended community attributes called VPN target attributes, or
route target attributes, to control the advertisement of VPN routing information. A VPN instance
on a PE supports two types of VPN target attributes:
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Export target attribute: A local PE sets this type of VPN target attribute for VPN-IPv4 routes
learnt from directly connected sites before advertising them to other PEs.
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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, VPN target attributes define which sites can receive VPN-IPv4 routes, and from
which sites that a PE can receive routes. Like RDs, VPN target attributes can be of two types of
formats:
1. 16-bit AS number:32-bit user-defined number. For example, 100:1.
2. 32-bit IPv4 address:16-bit user-defined number. For example, 172.1.1.1:1.
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MP-BGP
Multiprotocol extensions for BGP-4 (MP-BGP) advertises VPN composition and routing
information between PEs. It is backward compatible and supports both traditional IPv4 address
family and other address families, such as VPN-IPv4 address family. Using MP-BGP can
guarantee that private routes of a VPN are advertised only in the VPN and implement
communications between MPLS VPN members.
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Routing policy
In addition to the import and export extended communities for controlling VPN route
advertisement, you can also configure import and export routing policies to control the injection
and advertisement of VPN routes more precisely. An import routing policy can further filter
the routes that can be advertised to a VPN instance by using the VPN target attribute of import
target attribute. It can reject the routes selected by the communities in the import target attribute.
An export routing policy can reject the routes selected by the communities in the export target
attribute. After a VPN instance is created, you can configure import and/or export routing
policies as needed.
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Tunneling policy
A tunneling policy is used to select the tunnel for the packets of a specific VPN instance to
use. After a VPN instance is created, you can optionally configure a tunneling policy. By
default, LSPs are used as tunnels and no load balancing occurs (in other words, the number
of tunnels for load balancing is 1). In addition, a tunneling policy takes effect only within the
local AS.
36 MPLS Manager