Brocade Virtual ADX Switch and Router Guide (Supporting ADX v03.1.00) - Manual (Page 229)

Brocade Virtual ADX Switch and Router Guide 215
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Four-byte Autonomous System Numbers (AS4)
8
The no form of the capability command deletes the announcement and negotiation configuration
of AS4s (if it has been enabled) at the global level. Using the regular form of the command with the
disable keyword has the same effect on the global configuration. Disabling or using the no form of
the command does not affect the configuration at the level of a peer or neighbor.
The consequences of choosing between the enable or disable keyword are reflected in the output
of the show running configuration command.
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 10.1.1.1 illustrates.
Virtual ADX(config-bgp)# neighbor 10.1.1.1 capability as4 enable
Syntax: [no] neighbor IP address capability as4 enable | disable
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.
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 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.
Virtual ADX(config)# router bgp
BGP4: Please configure 'local-as' parameter in order to enable BGP4.
Virtual ADX(config-bgp)# local-as 100000
Virtual ADX(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 a AS4 number to an AS path or make the AS number a tag attribute for a route
map, as shown here.
Virtual ADX(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.