Routing Policy Application; Configuring Ip Routing Policy - 3Com 8800 Configuration Manual

3Com Switch 8800 Configuration Guide
II. ip-prefix
The function of the ip-prefix is similar to that of the acl, but it is more flexible and easy
for the users to understand. When the ip-prefix is applied to the routing information
filtering, its matching objects are the destination address information domain of the
routing information.
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.
III. as-path
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.
IV. community-list
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.

22.1.2 Routing Policy Application

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.

22.2 Configuring IP Routing Policy

The routing policy configuration includes:
1) Filter configuration includes:
Configuring a Route-policy
Configuring Access Control List (ACL)
Chapter 22 IP Routing Policy Configuration
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