Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 456)

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.
Route-map set commands and AS4s
You can prepend an AS4 number to an autonomous system path or make the autonomous system
number a tag attribute for a route map as shown here.
device(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 autononous system 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.
Clearing BGP4 routes to neighbors
You can clear BGP4 connections using the AS4 as an argument with the clear ip bgp neighbor
command in the configuration context level of the CLI. as shown.
device(config)# clear ip bgp neighbor 80000
Syntax: clear ip bgp neighbor all | ip-addr | peer-group-name | as-num [ last-packet-with-error |
notification-errors | [ soft [ in | out ] | soft-outbound ]
The neighbor specification is either all, ip-addr , peer-group-name , or as-num . The all parameter
specifies all neighbors. The ip-addr parameter specifies a neighbor by its IP interface with the device.
Specifying the local AS number
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