Configure 4-byte AS numbers

Configure AS numbers using the 4-byte format and represent the numbers in octets.

Before you begin

  • You cannot modify the global BGP configuration unless BGP is disabled.

  • Make sure that you define AS numbers in policies the same way that you configure them for the router. The choices are asplain (regular expression) or asdot (dot notation). If you create policies using asplain and configure the switch with asdot, the match will not occur.

About this task

Use BGP 4–byte AS numbers to ensure the continuity of loop-free inter-domain routing information between autonomous systems and to control the flow of BGP updates as 2 byte AS numbers will deplete soon. AS Plain notation format is the default and the preferred form of representing 4–byte AS numbers over the AS dot notation format.

You have an option to configure AS dot notation format as well. With AS dot notation, analyzing and troubleshooting any issues encountered becomes difficult as it is incompatible with the regular expressions used by most of the network providers.

If you enable 4-byte AS numbers, or the dotted octet notation, for the Global Router (VRF0), the configuration is inherited by user-defined VRFs. You cannot enable 4-byte AS numbers on individual user-defined VRFs.

Procedure

  1. In the navigation pane, expand Configuration > IP.
  2. Select BGP.
  3. Select the Generals tab.
  4. To change the AS number format, select disable for AdminStatus.
  5. Select Apply.
  6. In 4-byteAs , select enable.
  7. In AsDot, select enable.
  8. In LocalAs, type the 4-byte AS number in octets.
  9. In AdminStatus, select enable.
  10. Select Apply.

4–byte AS Field Descriptions

Use the data in the following table to use the 4–byte AS related fields on the Generals tab.

Name

Description

LocalAs

Configures the local autonomous system (AS) number. You cannot change this field when AdminStatus is set to enable. This field sets a 2-byte local AS number in the range from 0 to 65535. To set a 4-byte local AS number, click enable in the 4ByteAs field and enter a number in the LocalAs field.

Attention: The switch does not support this parameter with BGP +.

4byteAs

Enables or disables the switch from using 4 byte numbers for autonomous systems.

AsDot

Enables or disables representing AS numbers in octects. The default is disable so the switch uses the plain notation format. If you enable this field and the 4ByteAs field, enter the AS number in the LocalAs field.

Attention: The switch does not support this parameter with BGP +.
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