check-first-as

Function

The check-first-as command enables the function to check the first AS number in the AS_Path list that is carried in the Update message sent by the EBGP peer.

The undo check-first-as command disables the function.

By default, the function is enabled.

Format

check-first-as

undo check-first-as

Parameters

None

Views

BGP view

Default Level

2: Configuration level

Usage Guidelines

By default, BGP checks the first AS number in the AS_Path list that is carried in the Update message sent by the EBGP peer. If only the first AS number indicates the AS where the EBGP peer locates, the Update message is accepted. Otherwise, the Update message is denied, and the EBGP connection goes Down.

The check-first-as command is not listed in the configuration file.
After the undo check-first-as command is configured, loops have a greater chance to occur. Therefore, use the command with caution.

After configurations are modified, you need run the refresh bgp command.

Example

# Check the first AS number in the AS_Path list that is carried in the Update message sent by the EBGP peer.

<sysname> system-view

[sysname] bgp 100

[sysname-bgp] check-first-as