24.7.3 AS_PATH Attribute Aggregation

When a summarized route includes a BGP4+ route among its source routes, the summarized route is tagged with the path attribute of the BGP4+ route. If the source routes include more than one BGP4+ route, the path attributes are summarized among those routes. The AS_PATH and COMMUNITIES attributes of summarized routes are edited as follows:

<Structure of this section>

(1) AS_PATH attribute

The initial AS path segment within the AS_SEQUENCE type of the AS_PATH attribute which is common to the summarization source routes is assigned as the AS_SEQUENCE type of the AS_PATH attribute of the summarized route. All other AS paths in the AS_SEQUENCE type and those outside the AS_SEQUENCE type appear in the AS_SET type of the AS_PATH attribute of the summarized route only if you execute the ipv6 summary-address configuration command with the as_set parameter specified.

(2) COMMUNITIES Properties

Every community in the summarization source BGP4+ routes is set to the COMMUNITIES attribute of the summarized route.