This lab will configure all three routers to form iBGP relationships with each other.

1. Connect R1: G0/0/0/2 to R3: G0/0/0/2
2. On R1:
   1. IP: 10.0.2.2/24
   2. BGP ASN 65000
3. On R3: 10.0.2.3/24
   1. BGP ASN 65000
4. Add a neighbor and network statement to R3 from R1 and vice-versa.
   1. Answer R1

      router bgp 65000
       address-family ipv4 unicast
        network 10.0.2.0/24
       ! 
       neighbor 10.0.2.3
        remote-as 65000
        address-family ipv4 unicast

   2. Answer R3

      router bgp 65000
       address-family ipv4 unicast
        network 10.0.2.0/24
       ! 
       neighbor 10.0.2.1
        remote-as 65000
        address-family ipv4 unicast

5. Verify

   1. RP/0/0/CPU0:R3#show bgp summ
      Neighbor        Spk    AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down  St/PfxRcd
      10.0.0.2          0 65000      24      24      779    0    0 00:18:58          3
      10.0.1.2          0 65000      25      27      779    0    0 00:22:02          3
      10.0.2.2          0 65000       4       4      779    0    0 00:00:11          3

   2. RP/0/0/CPU0:R3#show bgp nei 10.0.0.2 | i BGP state
      BGP state = Established, up for 01:44:11

   3. RP/0/RP0/CPU0:R3#show route bgp
      Tue Feb  4 14:13:28.337 UTC
      
      B    1.1.1.1/32 [200/0] via 10.0.0.2, 00:00:00
      B    2.2.2.2/32 [200/0] via 10.0.1.2, 00:23:32
      B    10.0.0.0/24 [200/0] via 10.0.0.2, 00:00:00

   4. RP/0/RP0/CPU0:R3#show route bgp
      Thu Feb  6 13:46:14.638 UTC
      
      B    1.1.1.1/32 [200/0] via 10.0.2.2, 00:20:02
      B    2.2.2.2/32 [200/0] via 10.0.1.2, 06:09:40
      B    10.0.0.0/24 [200/0] via 10.0.2.2, 00:20:02

   5. Now R1 and R3 have a physical full-mesh iBGP relationship.

IOS-XR Lab 8: iBGP with Three Routers part 4 - using loopback peering
IOS-XR Lab Index