Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 59)

Multi-Service IronWare Routing Configuration Guide 31
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Four-byte Autonomous System Numbers (AS4)
The no form of the neighbor command with the capability 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.
Brocade(config-bgp)# neighbor 10.1.1.1 capability as4 disable
Specifying the local AS number
The local autonomous system number (ASN) identifies the AS 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 AS number, enter commands such as the following.
Brocade(config)# router bgp
BGP4: Please configure 'local-as' parameter in order to enable BGP4.
Brocade(config-bgp)# local-as 100000
Brocade(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 AS numbers and are not advertised to the
Internet community.
Route-map set commands and AS4s
You can prepend an AS4 number to an AS path or make the AS number a tag attribute for a route
map, as shown here.
Brocade(config-routemap test)# set as-path prepend 7701000
Syntax: [no] set as-path prepend num, num, ... | tag
Use the no form of this command to remove the configuration.
NOTE
If the AS path for a route map has prepended ASNs and you want to use the no form of the command
to delete the configuration, you must include the prepended ASNs in the no set as-path entry. For
example, if 70000 and 70001 have been prepended to a route map, enter no set as-path prepend
70000 70001. As a shortcut, in the configuration context of a particular route map, you can also
copy and paste ASNs from the output of show commands, such as show route-map or show ip bgp
route.
Use the prepend keyword to prepend one or more ASNs. The maximum number of ASNs that you
can prepend is 16. The range for each ASN is 1 – 4294967295.
Entering the tag keyword sets the tag as an AS-path attribute.