The
external-distance
sets the EBGP distance and can be a value from 1 through 255.
The
internal-distance
sets the IBGP distance and can be a value from 1 through 255.
The
local-distance
sets the Local BGP4 distance and can be a value from 1 through 255.
Requiring the first AS to be the neighbor AS
By default, the Brocade device does not require the first AS listed in the AS_SEQUENCE field of an AS path update message from
EBGP neighbors to be the AS of the neighbor that sent the update. However, you can enable the Brocade device to have this
requirement. You can enable this requirement globally for the device, or for a specific neighbor or peer group. This section describes how
to enable this requirement.
When you configure the device to require that the AS an EBGP neighbor is in be the same as the first AS in the AS_SEQUENCE field of
an update from the neighbor, the device accepts the update only if the AS numbers match. If the AS numbers do not match, the Brocade
device sends a notification message to the neighbor and closes the session. The requirement applies to all updates received from EBGP
neighbors.
The hierarchy for enforcement of this feature is: a neighbor will try to use the enforce-first-as value if one is configured; if none is
configured, the neighbor will try to use the configured value for a peer 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
Optional BGP4 configuration tasks
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