Technical Documentation

Supported Platforms
EX Series
M Series
T Series

Related Topics
autonomous-system
family
Configuring a Local AS for EBGP Sessions

local-as

Syntax

local-as autonomous-system <loops number> <private | alias> <no-prepend-global-as>;

Hierarchy Level

[edit logical-systems logical-system-name protocols bgp],[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],[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],[edit protocols bgp group group-name],[edit protocols bgp group group-name neighbor address],[edit routing-instances routing-instance-name protocols bgp],[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 OS Release 7.4.

Statement introduced in Junos OS Release 9.0 for EX Series switches.

alias option introduced in Junos OS Release 9.5.

no-prepend-global-as option introduced in Junos OS Release 9.6.

Description

Set the local AS number.

In Junos OS Release 9.1 and later, the autonomous system (AS) numeric range in plain-number format is extended to provide BGP support for 4-byte AS numbers, as defined in RFC 4893, BGP Support for Four-octet AS Number Space.

In Junos OS Release 9.3 and later, you can also configure a 4-byte AS number using the AS-dot notation format of two integer values joined by a period: <16-bit high-order value in decimal>.<16-bit low-order value in decimal>. For example, the 4-byte AS number of 65546 in plain-number format is represented as 1.10 in the AS-dot notation format.

Options

alias—(Optional) Configure the local AS as an alias of the global AS number configured for the router at the [edit routing-options] hierarchy level. As a result, a BGP peer considers any local AS to which it is assigned as equivalent to the primary AS number configured for the routing device. When you use the alias option, only the AS (global or local) used to establish the BGP session is prepended in the AS path sent to the BGP neighbor.

autonomous-system—AS number.

Range: 1 through 4,294,967,295 (2³² – 1) in plain-number format

Range: 0.0 through 65535.65535 in AS-dot notation format

loops number—(Optional) Specify the maximum number of times that the local AS number can appear in an AS path received from a BGP peer. For number, include a value from 1 through 10.

no-prepend-global-as—(Optional) Specify to strip the global AS and to prepend only the local AS in AS paths sent to external peers.

private—(Optional) Configure to use the local AS only during the establishment of the BGP session with a BGP neighbor but to hide it in the AS path sent to external BGP peers. Only the global AS is included in the AS path sent to external peers.

Note: The private and alias options are mutually exclusive. You cannot configure both options with the same local-as statement.

Required Privilege Level

routing—To view this statement in the configuration.

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