OS10 Enterprise Edition User Guide Release 10.4.1.0

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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 configured 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 specified number of times in ROUTER-BGP-NEIGHBOR-AF mode (1 to 10).
    allowas-in 
                                           number
                                        

Configure 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
                                 Path source: I - internal, a - aggregate, c - confed-external,
                                 r - redistributed/network, S - stale
                                 Origin codes: i - IGP, e - EGP, ? - incomplete
                                 Network         Next Hop      Metric     LocPrf     Weight     Path           
                                 *>I       55::/64         172:16:1::2   0          0          0          100 200 300 400 i
                                 *>I       55:0:0:1::/64   172:16:1::2   0          0          0          100 200 300 400 i
                                 *>I       55:0:0:2::/64   172:16:1::2   0          0          0          100 200 300 400 i
                              

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