Specifications

neighbor allowas-in
MP-364
Cisco IOS Multiprotocol Label Switching Command Reference
January 2010
neighbor allowas-in
To configure provider edge (PE) routers to allow readvertisement of all prefixes containing duplicate
autonomous system numbers (ASNs), use the neighbor allowas-in command in router configuration
mode. To disable the readvertisement of the ASN of the PE router, use the no form of this command.
neighbor i
p-address allowas-in [number]
no neighbor a
llowas-in [number]
Syntax Description
Command Default Readvertisement of all prefixes containing duplicate ASNs is disabled by default.
Command Modes Router configuration
Command History
Usage Guidelines In a hub and spoke configuration, a PE router readvertises all prefixes containing duplicate autonomous
s
ystem numbers. Use the neighbor allowas-in command to configure two VRFs on each PE router to
receive and readvertise prefixes are as follows:
• One Virtual Private Network routing and forwarding (VRF) instance receives prefixes with ASNs
from all PE routers and then advertises them to neighboring PE routers.
• The other VRF receives prefixes with ASNs from the customer edge (CE) router and readvertises
them to all PE routers in the hub and spoke configuration.
You control the number of times an ASN is advertised by specifying a number from 1 to 10.
ip-address IP address of the neighboring router.
number (Optional) Specifies the number of times to allow the advertisement
of a PE ro
uter’s ASN. Valid values are from 1 to 10. If no number is
supplied, the default value of 3 times is used.
Release Modification
12.0(7)T This command was introduced.
12.1 This command was integrated into Cisco IOS Release 12.1.
12.2 This command was integrated into Cisco IOS Release 12.2.
12.3 This command was integrated into Cisco IOS Release 12.3.
12.3T This command was integrated into Cisco IOS Release 12.3T.
12.4 This command was integrated into Cisco IOS Release 12.4.
12.4T This command was integrated into Cisco IOS Release 12.4T.
12.2(33)SRA This command was integrated into Cisco IOS Release 12.2(33)SRA.
12.2SX This command is supported in the Cisco IOS Release 12.2SX train.
S
upport in a specific 12.2SX release of this train depends on your
feature set, platform, and platform hardware.