as-override

Syntax

as-override;

Hierarchy Level

[edit protocols bgp group group-name],
[edit protocols bgp group group-name neighbor address],
[edit routing-instances routing-instance-name protocols bgp group group-name],
[edit routing-instances routing-instance-name protocols bgp group group-name
    neighbor address],
[edit logical-routers logical-router-name protocols bgp group group-name],
[edit logical-routers logical-router-name protocols bgp group group-name neighbor address],
[edit logical-routers logical-router-name routing-instances routing-instance-name protocols bgp
    group group-name],
[edit logical-routers logical-router-name routing-instances routing-instance-name protocols bgp
    group group-name     neighbor address]

Description

Compare the AS path of an incoming advertised route with the AS number of the BGP peer under the group and replace all occurrences of the peer AS number in the AS path with its own AS number before advertising the route to the peer.

Enabling the AS override feature allows routes originating from an AS to be accepted by a router residing in the same AS. Without AS override enabled, the router refuses the route advertisement once the AS path shows that the route originated from its own AS. This is done by default to prevent route loops. The as-override statement overrides this default behavior.

Note that enabling the AS override feature results in possible occurrence of routing loops. This feature should only be used for specific applications that require this type of behavior, and in situations with strict network control. One application is the IGP protocol between the Provider-Edge router and the Customer-Edge router within a Virtual Private Network. For more information, see the JUNOS Internet Software Configuration Guide: MPLS Applications.

Required Privilege Level

routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.