Control the Aggregator Path Attribute

The JUNOS implementation of BGP performs route aggregation, which is the process of combining the characteristics of different routes so that only a single route is advertised. Aggregation reduces the amount of information that BGP must store and exchange with other BGP systems.

BGP adds the aggregator path attribute to BGP update messages. This attribute contains the local system's AS number and IP address (router ID).

To prevent different routers within an AS from creating aggregate routes that contain different AS paths, set the IP address in the aggregator path attribute to 0 by including the no-aggregator-id statement:

no-aggregator-id; 

You can control the aggregator path attribute globally for all BGP groups (at the [edit protocols bgp] hierarchy level), for all peers in a group (at the [edit protocols bgp group group-name] level), or for an individual peer (at the [edit protocols bgp group group-name neighbor address] level). For routing instances, include the statement at the [edit routing-instances routing-instance-name protocols bgp] hierarchy level, [edit routing-instances routing-instance-name protocols bgp group group-name] hierarchy level, and the [edit routing-instances routing-instance-name protocols bgp group group-name neighbor address] hierarchy level.