3com 8807 Reference Guide

route-tag tag-number

OSPF protocol view

tag-number: Tag value to identify VPN import route, in the range of 0 to 
4294967295. By default, its first two bytes are fixed to 0xD000, while the last two 
bytes are the ASN of local BGP. For example, if the local BGP ASN is 100, then the 
default tag value in decimal is 3489661028. The value is an integer from 0 to 
4294967295.

Use the route-tag command to specify a tag value to identify VPN import route.

Use the undo route-tag command to restore the default value.

If a VPN Site is linked to multiple PEs, when a route learned from MPLS/BGP is 
advertised by a PE router via its type-5 or type-7 LSA to the VPN Site, the route 
may be received by another PE router. This will result in routing loop. To avoid 
routing loop, you should configure Route-tag and you are recommended to 
configure the same route-tag for the PEs in the same VPN domain. The Route-tag 
is included in the type-5/-7 LSA. It is not transmitted in the extended community 
attributes of BGP, and thus it is limited in the local area. Therefore, it can only be 
configured and function on the PE router which receives BGP routes and generates 
OSPF LSA.

Configure Route-tag in OSPF protocol view. Different processes can be configured 
with a same Route-tag. You can configure the same Route-tag using different 
commands, but they are different in priority.

■

Those configured with the import-route command are of the highest priority.

■

Those configured with the route-tag command are in the second place in 
terms of priority.

■

Those configure with the default tag command are of the lowest priority.

If the Tag included in the type-5/-7 LSA is identical with its existing Tag, the LSA 
received will be neglected in route calculation.

c 

Related command: import-route and default.

# Configure Route-tag 100 to OSPF process 100.

[3Com-ospf-100] route-tag 100

 

 OSPF: Process 100’s route tag has been changed