3com 8807 User Guide

C

HAPTER

 34: IP R

OUTING

 P

OLICY

 C

ONFIGURATION

An IP-prefix is identified by the IP-prefix name. Each IP-prefix can include multiple 
list items, and each list item can independently specify the match range of the 
network prefix forms and is identified with an index-number. The index-number 
designates the matching check sequence in the IP-prefix.

During the matching, the router checks list items identified by the 
sequence-number in the ascending order. Once a single list item meets the 
condition, it means that it has passed the IP-prefix filtering and will not enter the 
testing of the next list item.

The AS-path list is only used in the BGP. The routing information packet of the BGP 
includes an autonomous system path domain (During the process of routing 
information exchanging of the BGP, the autonomous system paths the routing 
information has passed through will be recorded in this domain). Targeting at the 
AS path domain, the AS-path specifies the match condition.

The community-list is only used in the BGP. The routing information packet of the 
BGP includes a community attribute domain to identify a community. Targeting at 
the community attribute, the community-list specifies the match condition.

Two routing policy applications are as follows:

When advertising/receiving routing information, the router filters the information 
according to the route policy, and receives or advertises the routing information 
which can meet the specified condition only.

When importing other routes detected by other routing protocol, the router only 
imports the routing information, which can meet the specified condition only, 
according to the route policy.

The routing policy configuration includes:

1 Filter configuration includes:

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2 Applications of routing policies include:

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A route-policy can comprise multiple nodes. Each node is a unit for matching 
operation. The nodes will be tested against by node-number.