Technical Documentation

as-override

Syntax

as-override;

Hierarchy Level

[edit logical-systems logical-system-name protocols bgp group group-name],[edit logical-systems logical-system-name protocols bgp group group-name neighbor address],[edit logical-systems logical-system-name routing-instances routing-instance-name protocols bgp group group-name],[edit logical-systems logical-system-name routing-instances routing-instance-name protocols bgp group group-name neighbor address],[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]

Release Information

Statement introduced before JUNOS Release 7.4.

Statement introduced in JUNOS Release 9.0 for EX Series switches.

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.

Note: The as-override statement is specific to a particular BGP group. This statement does not affect peers from the same remote AS configured in different groups.

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 routing device 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 may result in routing loops. Use this feature only 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 routing device and the customer edge routing device in a virtual private network. For more information, see the JUNOS MPLS Applications Configuration Guide.

Required Privilege Level

routing—To view this statement in the configuration.

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


Published: 2010-04-14