Brocade Communications Systems FastIron X Series User Manual

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 rst AS to be the neighbor AS
By default, the Brocade device does not require the
rst AS listed in the AS_SEQUENCE eld 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 specic neighbor or peer group. This section describes how
to enable this requirement.
When you congure the device to require that the AS an EBGP neighbor is in be the same as the rst AS in the AS_SEQUENCE eld 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 notication 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-rst-as value if one is congured; if none is
congured, the neighbor will try to use the congured value for a peer group. If neither conguration exists, enforcement is simply that of
the global conguration (which is disabled by default).
To enable this feature globally, enter the enforce-rst-as command at the BGP4 conguration level of the CLI.
device(config-bgp-router)# enforce-first-as
Syntax: [no]
enforce-rst-as
To enable this feature for a specic neighbor, enter the following command at the BGP4 conguration level.
device(config-bgp)# neighbor 10.1.1.1 enforce-first-as enable
Syntax: [no] neighbor ip-address enforce-rst-as [ enable | disable ]
The ip-address value is the IP address of the neighbor.
When the rst-as requirement is enabled, its status appears in the output of the show running conguration command. The optional last
keyword choice of enable or disable lets you specify whether the output of the show running conguration command includes the
conguration of the rst-as requirement. This option allows the show running conguration command output to show what is actually
congured.
To enable this feature for a peer group, enter the following command at the BGP4 conguration level.
device(config-bgp)# neighbor Peergroup1 enforce-first-as enable
Syntax: [no] neighbor peer-group-name enforce-rst-as [ enable | disable ]
The peer-group-name value is the name of the peer group.
When the rst-as requirement is enabled, its status appears in the output of the show running conguration command. The optional last
keyword choice, that of enable or disable , lets you specify whether the output of the show running conguration command includes the
conguration of the rst-as requirement: this option helps the show running command output to show what you have actually congured.
The following example shows a running conguration with the rst-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 conguration tasks
FastIron Ethernet Switch Layer 3 Routing
386 53-1003627-04

Brocade Communications Systems FastIron X Series Specifications

General

Brand	Brocade Communications Systems
Model	FastIron X Series
Category	Switch
Language	English