Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 421)

group. If neither configuration exists, enforcement is simply that of the global configuration (which is
disabled by default).
To enable this feature globally, enter the enforce-first-as command at the BGP4 configuration level of
the CLI.
device(config-bgp-router)# enforce-first-as
Syntax: [no] enforce-first-as
To enable this feature for a specific neighbor, enter the following command at the BGP4 configuration
level.
device(config-bgp)# neighbor 10.1.1.1 enforce-first-as enable
Syntax: [no] neighbor ip-address enforce-first-as [ enable | disable ]
The ip-address value is the IP address of the neighbor.
When the first-as requirement is enabled, its status appears in the output of the show running
configuration command. The optional last keyword choice of enable or disable lets you specify
whether the output of the show running configuration command includes the configuration of the first-
as requirement. This option allows the show running configuration command output to show what is
actually configured.
To enable this feature for a peer group, enter the following command at the BGP4 configuration level.
device(config-bgp)# neighbor Peergroup1 enforce-first-as enable
Syntax: [no] neighbor peer-group-name enforce-first-as [ enable | disable ]
The peer-group-name value is the name of the peer group.
When the first-as requirement is enabled, its status appears in the output of the show running
configuration command. The optional last keyword choice, that of enable or disable , lets you specify
whether the output of the show running configuration command includes the configuration of the first-as
requirement: this option helps the show running command output to show what you have actually
configured.
The following example shows a running configuration with the first-as enforcement items (for global,
peer group, and neighbor) in bold.
device(config)# router bgp
BGP4: Please configure 'local-as' parameter in order to enable BGP4.
device(config-bgp)# local-as 1
device(config-bgp)# enforce-first-as
device(config-bgp)# neighbor abc peer-group
device(config-bgp)# neighbor abc remote-as 2
device(config-bgp)# neighbor abc enforce-first-as disable
device(config-bgp)# neighbor 192.168.1.2 peer-group abc
device(config-bgp)# neighbor 192.168.1.2 enforce-first-as enable
Disabling or re-enabling comparison of the AS-Path length
AS-Path comparison is Step 5 in the algorithm that BGP4 uses to select the next path for a route.
Comparison of the AS-Path length is enabled by default. To disable it, enter the following command at
the BGP4 configuration level of the CLI.
device(config-bgp)# as-path-ignore
Syntax: [no] as-path-ignore
Disabling or re-enabling comparison of the AS-Path length
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