autonomous-system
Syntax autonomous-system autonomous-system <asdot-notation> <loops number> {
independent-domain <no-attrset>;
}
Hierarchy Level [edit logical-systems logical-system-name routing-instances routing-instance-name
routing-options],
[edit logical-systems logical-system-name routing-options],
[edit routing-instances routing-instance-name routing-options],
[edit routing-options]
Release Information Statement introduced before Junos OS Release 7.4.
Statement introduced in Junos OS Release 9.0 for EX Series switches.
asdot-notation option introduced in Junos OS Release 9.3.
asdot-notation option introduced in Junos OS Release 9.3 for EX Series switches.
no-attrset option introduced in Junos OS Release 10.4.
Statement introduced in Junos OS Release 11.3 for the QFX Series.
Statement introduced in Junos OS Release 12.3 for ACX Series routers.
Statement introduced in Junos OS Release 14.1X53-D20 for the OCX Series.
Description Specify the routing device’s AS number.
An autonomous system (AS) is a set of routing devices that are under a single technical
administration and that generally use a single interior gateway protocol (IGP) and metrics
to propagate routing information within the set of routing devices. An AS appears to other
ASs to have a single, coherent interior routing plan and presents a consistent picture of
what destinations are reachable through it. ASs are identified by a number that is assigned
by the Network Information Center (NIC) in the United States (http://www.isi.edu).
If you are using BGP on the routing device, you must configure an AS number.
The AS path attribute is modified when a route is advertised to an EBGP peer. Each time
a route is advertised to an EBGP peer, the local routing device prepends its AS number
to the existing path attribute, and a value of 1 is added to the AS number.
In Junos OS Release 9.1 and later, the numeric range is extended to provide BGP support
for 4-byte AS numbers as defined in RFC 4893, BGP Support for Four-octet AS Number
Space. RFC 4893 introduces two new optional transitive BGP attributes, AS4_PATH and
AS4_AGGREGATOR. These new attributes are used to propagate 4-byte AS path
information across BGP speakers that do not support 4-byte AS numbers. RFC 4893
also introduces a reserved, well-known, 2-byte AS number, AS 23456. This reserved AS
number is called AS_TRANS in RFC 4893. All releases of Junos OS support 2-byte AS
numbers.
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 65,546 in plain-number format is represented as 1.10 in the AS-dot notation format.
Copyright © 2017, Juniper Networks, Inc.1444
ACX Series Universal Access Router Configuration Guide
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