• Supported Platforms
• EX Series
• M Series
• T Series

• Related Topics
• Configuring BGP Groups and Peers
• Configuring BGP Groups and Peers
• 4-Byte Autonomous System Numbers Overview in the Using 4-Byte Autonomous System Numbers in BGP Networks Technology Overview
• Juniper Networks Implementation of 4-Byte Autonomous System Numbers in the Using 4-Byte Autonomous System Numbers in BGP Networks Technology Overview
• Establishing a Peer Relationship Between a 4-Byte Capable Router and a 2-Byte Capable Router Using a 2-Byte AS Number in the Using 4-Byte Autonomous System Numbers in BGP Networks Technology Overview
• Establishing a Peer Relationship Between a 4-Byte Capable Router and a 2-Byte Capable Router Using a 4-Byte AS Number in the Using 4-Byte Autonomous System Numbers in BGP Networks Technology Overview

peer-as

Syntax

Hierarchy Level

Release Information

Statement introduced before Junos OS Release 7.4.

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

Description

Specify the neighbor (peer) AS number.

The autonomous system (AS) numeric range in plain-number format has been extended in Junos OS Release 9.1 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 the Junos OS support 2-byte AS numbers.

In Junos OS Release 9.2 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.

Options

autonomous-system—AS number.

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

Range: 1 through 65,535 in plain-number format for 2-byte AS numbers (this is a subset of the 4-byte range)

Range: 0.0 through 65535.65535 in AS-dot notation format for 4-byte AS numbers

Required Privilege Level

routing—To view this statement in the configuration.

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