Tim's Technology Journey Wiki

1. Advertise the Loopback and G 0/0/0/0 interface on both routers. Be patient, BGP neighborship will form. Sometimes it could take a few mins for that neighborship to form.
   1. Answer

      RP/0/0/CPU0:R1(config)#router bgp 65000
      RP/0/0/CPU0:R1(config-bgp)#address-family ipv4 unicast 
      RP/0/0/CPU0:R1(config-bgp-af)#network 10.0.0.0/24
      RP/0/0/CPU0:R1(config-bgp-af)#network 1.1.1.1/32
      RP/0/0/CPU0:R1(config-bgp-af)#commit 

      RP/0/0/CPU0:R2(config)#router bgp 65000
      RP/0/0/CPU0:R2(config-bgp)#address-family ipv4 unicast 
      RP/0/0/CPU0:R2(config-bgp-af)#network 10.0.0.0/24
      RP/0/0/CPU0:R2(config-bgp-af)#network 2.2.2.2/32
      RP/0/0/CPU0:R2(config-bgp-af)#commit

2. Verify

   1. RP/0/0/CPU0:R1#show bgp ipv4 unicast
      BGP router identifier 1.1.1.1, local AS number 65000
         Network            Next Hop            Metric LocPrf Weight Path
      *> 1.1.1.1/32         0.0.0.0                  0         32768 i
      *>i2.2.2.2/32         10.0.0.3                 0    100      0 i
      *> 10.0.0.0/24        0.0.0.0                  0         32768 i
      * i                   10.0.0.3                 0    100      0 i
      
      Processed 3 prefixes, 4 paths

   2. RP/0/0/CPU0:R2#show bgp ipv4 unicast
      BGP router identifier 2.2.2.2, local AS number 65000
         Network            Next Hop            Metric LocPrf Weight Path
      *>i1.1.1.1/32         10.0.0.2                 0    100      0 i
      *> 2.2.2.2/32         0.0.0.0                  0         32768 i
      *> 10.0.0.0/24        0.0.0.0                  0         32768 i
      * i                   10.0.0.2                 0    100      0 i
      
      Processed 3 prefixes, 4 paths

   3. RP/0/0/CPU0:R1#show bgp ipv4 unicast neighbors 10.0.0.3 advertised-routes 
      Mon Dec 16 20:58:58.809 UTC
      Network            Next Hop        From            AS Path
      1.1.1.1/32         10.0.0.2        Local           i
      10.0.0.0/24        10.0.0.2        Local           i
      
      Processed 2 prefixes, 2 paths

   4. RP/0/0/CPU0:R2#show bgp ipv4 unicast neighbors 10.0.0.2 advertised-routes 
      Mon Dec 16 20:59:45.226 UTC
      Network            Next Hop        From            AS Path
      2.2.2.2/32         10.0.0.3        Local           i
      10.0.0.0/24        10.0.0.3        Local           i
      
      Processed 2 prefixes, 2 paths

   5. RP/0/0/CPU0:R1#show route bgp
      Mon Dec 16 21:00:48.261 UTC
      
      B    2.2.2.2/32 [200/0] via 10.0.0.3, 00:16:35

   6. RP/0/0/CPU0:R2#show route bgp
      Mon Dec 16 21:00:54.761 UTC
      
      B    1.1.1.1/32 [200/0] via 10.0.0.2, 00:19:33

   7. Notice the [200/0] next to the neighbor's address. The 200 is the Administrative Distance (AD). An AD of 200 means iBGP whereas eBGP would be 20.

IOS-XR Lab 5: iBGP
IOS-XR Lab Index