Using Access Lists In A Route Map; Configuration Example 1; Figure 4: Route Map Filtering - Juniper JUNOSE 11.2.X IP SERVICES Configuration Manual

JunosE 11.2.x IP Services Configuration Guide

Using Access Lists in a Route Map

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host1(config)#ip as-path access-list 2 permit .*
host1(config)#ip as-path access-list 3 deny [621 11]
host1(config)#ip as-path access-list 3 permit .*
AS-path access list 1 is applied to routes that router London receives from router Paris.
Router London rejects routes with the AS path 11 621 or 11 282 621.
AS-path access list 2 is applied to routes that router London receives from router Berlin.
Router London rejects routes with the AS path 621 11 or 621 282 11.
Router London accepts routes with the AS path 282 11, 282 621, 282 621 11, or 282 11 621.
However, it applies AS-path access list 3 to routes it forwards to router Madrid, and filters
out routes with the AS path 282 621 11 or 282 11 621.
You can use a route map instead of the neighbor filter-list command to apply access
lists for filtering routes.

Configuration Example 1

In Figure 4 on page 24, a route map is used to determine the weight for routes learned
by router Chicago.

Figure 4: Route Map Filtering

Access list 1 permits any route whose AS-path attribute includes 32 or 837. This condition
permits routes that originate in (or pass through from elsewhere) AS 32 or AS 837. When
these routes are advertised through AS 451 and AS 17 to router Chicago, instance 1 of
route map 1 matches such routes and sets their weight to 25, overriding the neighbor
weight set for updates received from 10.2.2.4.
Access list 2 permits any route whose AS-path attribute indicates that it originates in AS
74. When these routes are advertised through AS 837 and AS 32 to router Chicago,
instance 1 of route map 2 matches such routes and sets their weight to 175, overriding
the neighbor weight set for updates received from 10.5.5.2.
The following example configures router Chicago:
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