Command Reference Guide

3Com Router 5000 Family and Router 6000 Family if-match tag ● 157
Command Reference
if-match tag
Purpose Use the if-match tag command to match the tag field of OSPF route information.
Use the undo if-match tag command to cancel the existing matching rules.
Syntax if-match tag value
undo if-match tag
Parameters value
Specifies the required tag value.
Example Display how to define one if-match clause and enable the OSPF route information
whose tag field is 8 to pass the if-match clause.
[3Com -route-policy] if-match tag 8
View This command can be used in the following views:
■ Routing Policy view
Description When a route is redistributed from protocol A to protocol B, and is redistributed back
to protocol A on some other routers, protocol A allows the tag field of the routing
protocol update packet to be transferred to the peer, that is, the information in the
tag field can traverse from protocol A to protocol B and then back to protocol A,
without being lost.
OSPF, RIP2, ISIS, and BGP support the tag field, but RIP1 does not.
For example, when a BGP route is redistributed into OSPF and then redistributed back
to BGP on another router, the as-path attribute of the BGP route is lost. You can the
aplly tag command to set the OSPF tag field as as-path to guarantee the integrity of
the as-path attribute.