Dell EMC SmartFabric OS10 User Guide Release 10.5.1

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 | l2vpn evpn}

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BGP local RIB : Routes to be Added , Replaced , Withdrawn 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