R0106-HP MSR Router Series MPLS Command Reference(V7)

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• 32-bit AS number:16-bit user-defined number, where the minimum value of the AS number is 65536.
For example, 65536:1.
Usage guidelines
RDs enable VPNs to use the same address space. An RD and an IPv4 prefix comprise a unique VPN IPv4
prefix.
To change the RD of a VPN instance, you must delete the RD with the undo route-distinguisher command,
and then use the route-distinguisher command to configure a new RD.
Examples
# Configure RD 22:1 for VPN instance vpn1.
<Sysname> system-view
[Sysname] ip vpn-instance vpn1
[Sysname-vpn-instance-vpn1] route-distinguisher 22:1
route-tag
Use route-tag to configure an external route tag for redistributed VPN routes.
Use undo route-tag to restore the default.
Syntax
route-tag tag-value
undo route-tag
Default
If BGP runs within an MPLS backbone, and the BGP AS number is not greater than 65535, the first two
octets of the external route tag are 0xD000, and the last two octets are the local BGP AS number. For
example, if the local BGP AS number is 100, the external route tag value is 3489661028 (100 + the
decimal value of 0xD0000000). If the AS number is greater than 65535, the external route tag is 0.
Views
OSPF view
Predefined user roles
network-admin
Parameters
tag-value: Specifies the external route tag for redistributed VPN routes, in the range of 0 to 4294967295.
Usage guidelines
In a dual-homed scenario where OSPF runs between the CE and the connected PEs (PE-A and PE-B, for
example), you can use external route tags to avoid routing loops.
When PE-A redistributes BGP routes from the peer PE into OSPF, and advertises these routes in the Type
5 or 7 LSAs to the CE, PE-A adds the locally configured external route tag to the LSAs.
When PE-B receives the Type 5 or 7 LSAs advertised by the CE, it compares the external route tag in the
LSAs with the locally configured tag. If they are the same, PE-B ignores the LSA in route calculation to
avoid routing loops.
The commands used to configure the external route tag (in the descending order of tag priority) are as
follows: