Command Reference Guide

3Com Router 3000 Ethernet Family
Command Reference Guide
Chapter 6 IP Routing Policy Configuration
Commands
3Com Corporation
6-16
View
Routing policy view
Parameter
value: Specifies the required tag value.
Description
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.
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.
Related command: if-match interface, if-match acl, if-match ip-prefix, if-match ip
next-hop, if-match cost, route-policy, apply ip-address, apply cost, apply
local-preference, apply origin, and apply tag.
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
6.1.22 ip ip-prefix
Syntax
ip ip-prefix ip-prefix-name [ index index-number ] { permit | deny } network len
[ greater-equal greater-equal | less-equal less-equal ]
undo ip ip-prefix ip-prefix-name [ index index-number | permit | deny ]
View
System view
Parameter
ip-prefix-name: Specifies an address prefix list name. It identifies one address prefix list
uniquely.