Related Documentation
- M, MX, PTX, T Series
- 4-Byte Autonomous System Numbers Overview
- Configuring 4-Byte AS Numbers and BGP Extended Community Attributes
- Configuring 4-Byte Autonomous System Numbers
- Establishing a Peer Relationship Between a 4-Byte Capable Router and a 2-Byte Capable Router Using a 2-Byte AS Number
- Establishing a Peer Relationship Between a 4-Byte Capable Router and a 2-Byte Capable Router Using a 4-Byte AS Number
- Juniper Networks Implementation of 4-Byte Autonomous System Numbers
- Prepending 4-Byte AS Numbers in an AS Path
- Understanding 4-Byte AS Numbers and Route Loop Detection
- Understanding a 4-Byte Capable Router AS Path Through a 2-Byte Capable Domain
Understanding 4-Byte AS Numbers and Route Distinguishers
A route distinguisher (RD) is an 8-byte field prefixed to a service provider customer's IPv4 address. The resulting 12-byte field is a unique VPN-IPv4 address. The RD in BGP messages consists of two major fields, the type field (2 bytes) and value field (6 bytes). The type field determines how the value field should be interpreted.
The route distinguisher is configured as a 6-byte value that you can specify as as-number:number, where as-number is your assigned AS number and number (also known as an administrative number or assigned number subfield) is any 2-byte or 4-byte value. The AS number can be in the range from 1 through 4,294,967,295. If the AS number is a 2-byte value, the administrative number is a 4-byte value. If the AS number is 4-byte value, the administrative number is a 2-byte value.
An RD consisting of a 4-byte AS number and a 2-byte administrative number is defined as a type 2 route distinguisher in RFC 4364, BGP/MPLS IP Virtual Private Networks.
To configure an RD using a 4-byte AS number, append the letter “L” to the end of the number. In the following example, the 4-byte AS number is 7765000 and the administrative number is 1000:
If the router you are configuring is a BGP peer of a router that does not support 4-byte AS numbers, you also need to configure a local AS number as discussed in Establishing a Peer Relationship Between a 4-Byte Capable Router and a 2-Byte Capable Router Using a 4-Byte AS Number. To configure the local AS number, include the local-as statement, specify the 2-byte AS number to use (65001), and include the private option.
Related Documentation
- M, MX, PTX, T Series
- 4-Byte Autonomous System Numbers Overview
- Configuring 4-Byte AS Numbers and BGP Extended Community Attributes
- Configuring 4-Byte Autonomous System Numbers
- Establishing a Peer Relationship Between a 4-Byte Capable Router and a 2-Byte Capable Router Using a 2-Byte AS Number
- Establishing a Peer Relationship Between a 4-Byte Capable Router and a 2-Byte Capable Router Using a 4-Byte AS Number
- Juniper Networks Implementation of 4-Byte Autonomous System Numbers
- Prepending 4-Byte AS Numbers in an AS Path
- Understanding 4-Byte AS Numbers and Route Loop Detection
- Understanding a 4-Byte Capable Router AS Path Through a 2-Byte Capable Domain
Published: 2012-11-14
Related Documentation
- M, MX, PTX, T Series
- 4-Byte Autonomous System Numbers Overview
- Configuring 4-Byte AS Numbers and BGP Extended Community Attributes
- Configuring 4-Byte Autonomous System Numbers
- Establishing a Peer Relationship Between a 4-Byte Capable Router and a 2-Byte Capable Router Using a 2-Byte AS Number
- Establishing a Peer Relationship Between a 4-Byte Capable Router and a 2-Byte Capable Router Using a 4-Byte AS Number
- Juniper Networks Implementation of 4-Byte Autonomous System Numbers
- Prepending 4-Byte AS Numbers in an AS Path
- Understanding 4-Byte AS Numbers and Route Loop Detection
- Understanding a 4-Byte Capable Router AS Path Through a 2-Byte Capable Domain
