Connectivity Guide

AS number limit
Sets the number of times an AS number occurs in an AS path. The allow-as parameter permits a BGP speaker to allow the AS number
for a congured number of times in the updates received from the peer.
The AS-PATH loop is detected if the local AS number is present more than the number of times in the command.
1 Enter the neighbor IP address to use the AS path in ROUTER-BGP mode.
neighbor ip address
2 Enter Address Family mode in ROUTER-NEIGHBOR mode.
address-family {[ipv4 | ipv6] [unicast])
3 Allow the neighbor IP address to use the AS path the specied number of times in ROUTER-BGP-NEIGHBOR-AF mode (1 to 10).
allowas-in number
Congure AS number appearance
OS10(config)# router bgp 10
OS10(conf-router-bgp-10)# neighbor 1.1.1.2
OS10(conf-router-neighbor)# address-family ipv4 unicast
OS10(conf-router-bgp-neighbor-af)# allowas-in 5
View AS numbers in AS paths
OS10# show running-configuration bgp
!
router bgp 101
no fast-external-fallover
!
address-family ipv4 unicast
dampening
!
neighbor 17.1.1.2
remote-as 102
no shutdown
!
address-family ipv4 unicast
allowas-in 4
Show IP BGP
OS10(config)# router bgp 100
OS10(config-router-bgp-100)# neighbor 172:16:1::2
OS10(config-router-neighbor)# remote-as 100
OS10(config-router-neighbor)# no shutdown
OS10(config-router-neighbor)# address-family ipv6 unicast
OS10(config-router-bgp-neighbor-af)# activate
OS10(config-router-bgp-neighbor-af)# allowas-in 1
OS10(config-router-bgp-neighbor-af)# end
OS10# show running-configuration bgp
!
router bgp 100
!
neighbor 172:16:1::2
remote-as 100
no shutdown
!
address-family ipv6 unicast
activate
allowas-in 1
OS10# show ip bgp
BGP local RIB : Routes to be Added , Replaced , Withdrawn
BGP local router ID is 100.1.1.1
Status codes: s suppressed, S stale, d dampened, h history, * valid, > best
Layer 3
451