Bgp Enforce-First-As - Allied Telesis SwitchBlade x908 Series Software Reference Manual

BGP Commands
In the example above, the MED values were not considered when comparing the winners of
the two groups (the best routes from the different ASs). To use MED in the comparison of
routes from different ASs, use the bgp always-compare-med command.
Example
awplus(config-router)#
awplus(config-router)#
show ip bgp
Related Commands
show ip bgp neighbors

bgp enforce-first-as

Use this command to enforce the denying of eBGP updates in which the neighbor's AS
number is not the first AS in the AS-path attribute.
Use the no parameter with this command to disable this feature.
Syntax
bgp enforce-first-as
no bgp enforce-first-as
Router mode
Mode
This command specifies that any updates received from an external neighbor that do not have
Usage
the neighbor's configured Autonomous System (AS) at the beginning of the AS_PATH in the
received update must be denied. Enabling this feature adds to the security of the BGP network
by not allowing traffic from unauthorized systems.
Example
awplus(config-router#
38.20
awplus# configure terminal
awplus(config)# router bgp 100
bgp deterministic-med
awplus# configure terminal
awplus(config)# router bgp 100
no bgp deterministic-med
awplus# configure terminal
awplus(config)# router bgp 100
bgp enforce-first-as
Software Reference for SwitchBlade® x908, x900 and x600 Series Switches
TM
AlliedWare Plus Operating System - Software Version 5.3.1 C613-50007-01 REV B