Looped AS_Path Attribute

When an EBGP speaker receives a route from its neighbor, it must validate the AS_Path attribute to ensure that there is no loop in the AS_Path. When an EBGP speaker finds it's own AS-number in the received EBGP route's AS_Path attribute, it is considered as a Looped AS Path and by default, the associated EBGP routes are silently discarded.

There are certain cases (such as in a spoke and hub topology) where it becomes necessary to accept and process EBGP routes with a looped AS_Path attribute.

This feature enables you to control the processing of EBGP routes with a looped AS_Path attribute. You can do the following:


A looped AS path is always allowed for IBGP, irrespective of the BGP configuration.