Brocade Communications Systems FastIron SX 1600, Configuration Manual, Page: 420 / 593

The consequences of choosing between the enable or disable keyword are reflected in the output of the show running configuration
command.
Peer group configuration of AS4s
To enable AS4s for a peer group, use the capability keyword with the neighbor command in the BGP4 configuration context, as the
following example for the Peergroup_1 peer group illustrates.
device(config-bgp)# neighbor Peergroup_1 capability as4 enable
Syntax: [no] neighbor peer-group-name capability as4 enable | disable
The no form of the neighbor command along with the capability and as4 keywords disables the announcement and negotiation of AS4s
in the named peer group. Using the regular form of the command with the disable keyword has the same effect on the neighbor
configuration.
The consequences using the enable or disable keywords are reflected in the output of the show running configuration command.
However, if the peer group configuration omits an explicit AS4 argument, the show running configuration output will not contain AS4
information.
Neighbor configuration of AS4s
To enable AS4s for a neighbor, use the capability and as4 keywords with the neighbor command in the BGP4 configuration context, as
the following example for IP address 1.1.1.1 illustrates.
device(config-bgp)# neighbor 1.1.1.1 capability as4 enable
Syntax: [no] neighbor IPaddress capability as4 enable | disable
The no form of the neighbor command with the capability and as4 keywords deletes the neighbor-enable for AS4s.
The consequences of using the enable or disable keywords are reflected in the output of the show running configuration command.
However, if the neighbor configuration omits an explicit AS4 argument, the show running configuration output will not contain AS4
information.
To disable AS4s on a particular neighbor within a peer group that is enabled for AS4s, enter a command similar to the following.
device(config-bgp)# neighbor 1.1.1.1 capability as4 disable
Specifying the local AS number
The local autonomous system number (ASN) identifies the autonomous system where the BGP4 device resides.
Normally, AS4s are sent only to a device, peer group, or neighbor that is similarly configured for AS4s. Typically, if you try to set up a
connection from an AS4-enabled device to a device that processes only two-byte ASNs, the connection fails to come up unless you
specify the reserved ASN 23456 as the local ASN to send to the far-end device.
To set the local autonomous system number, enter commands such as the following.
device(config)# router bgp
BGP4: Please configure 'local-as' parameter in order to enable BGP4.
device(config-bgp)# local-as 100000
device(config-bgp)# write memory
Syntax: [no] local-as num
The num parameter specifies a local ASN in the range 1 - 4294967295. No default exists for num . ASNs 64512 - 65535 are the
well-known private BGP4 autonomous system numbers and are not advertised to the Internet community.
Four-byte Autonomous System Numbers (AS4)
FastIron Ethernet Switch Layer 3 Routing
420 53-1003627-04