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AGGREGATOR (optional, transitive)<br />

Indicates that the BGP router has summarized a range of prefixes.<br />

COMMUNITY (optional, transitive)<br />

Identifies an administrative or logical grouping of routes that share routing policies.<br />

Communities are represented by an identifier that includes the 16-bit AS<br />

number and a 16-bit community number. For example, in 65500:1001, the AS<br />

number is 65500 and the community number is 1001. BGP has three well-known<br />

communities:<br />

NO_EXPORT<br />

Routes cannot be advertised to EBGP peers but can be advertised within a<br />

BGP confederation.<br />

NO_ADVERTISE<br />

Routes cannot be advertised at all.<br />

LOCAL_AS<br />

Routes cannot be advertised to EBGP peers, even if the peers are in the same<br />

confederation.<br />

MP_REACH_NLRI and MP_UNREACH_NLRI (optional, nontransitive)<br />

Carry IPv6 NLRI information in MBGP.<br />

ORIGINATOR_ID (optional, nontransitive)<br />

Identifies a route reflector for IBGP. It is a 32-bit value that indicates the originator<br />

of the route within an AS.<br />

CLUSTER_LIST (optional, nontransitive)<br />

Lists route reflection identifiers of the clusters through which the route has<br />

passed. If a cluster sees its own identifier in the list, a loop has occurred and the<br />

route is ignored.<br />

13.1 Configuring a BGP Session Between Routers<br />

in Two ASs<br />

Problem<br />

You want to configure BGP on the border routers that connect the two different ASs.<br />

Solution<br />

Configure the autonomous system number and router ID on each router:<br />

[edit routing-options]<br />

aviva@RouterF# set autonomous-system 65500<br />

aviva@RouterF# set router-id 192.168.16.1<br />

422 | Chapter 13: BGP<br />

This is the Title of the Book, eMatter Edition<br />

Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved.

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