As-Override - Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual

as-override

Syntax
Hierarchy Level
Release Information
Description
Required Privilege
Level
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Documentation
Copyright © 2010, Juniper Networks, Inc.
as-override;
[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]
Statement introduced before Junos OS Release 7.4.
Statement introduced in Junos OS Release 9.0 for EX Series switches.
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 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
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 OS MPLS Applications Configuration Guide.
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.
Configuring BGP Groups and Peers
Chapter 79: Configuration Statements for Layer 3 Protocols
statement is specific to a particular BGP group. This
as-override
statement overrides
1955