This lab will configure a third router to form iBGP with three routers. This lab will fail, but will be fixed in Lab 6.

1. Configure a third BGP router, connected to R2's G0/0/0/1 interface, with the following parameters:
   1. Hostname=R3
   2. Lo0=3.3.3.3/32
   3. G0/0/0/1=10.0.1.3/24
   4. BGP ASN=65000
   5. BGP router-id=3.3.3.3
   6. HSRP not required at this time
   7. Answer

      hostname R3
      interface Loopback0
       ipv4 address 3.3.3.3 255.255.255.255
      !
      interface GigabitEthernet0/0/0/1
       description R2; G 0/0/0/1; 10.0.0.1.2/24
       ipv4 address 10.0.1.3 255.255.255.0
      !
      router bgp 65000
       bgp router-id 3.3.3.3
       address-family ipv4 unicast
        network 3.3.3.3/32
        network 10.0.1.0/24
       !
       neighbor 10.0.0.2
        remote-as 65000
        address-family ipv4 unicast
        !
       !
       neighbor 10.0.1.2
        remote-as 65000
        address-family ipv4 unicast

2. On R2:
   1. G0/0/0/1=10.0.1.2/24
   2. BGP ASN=65000
      1. Answer

         interface GigabitEthernet0/0/0/1
          description R3; G 0/0/0/1; 10.0.1.3/24
          ipv4 address 10.0.1.2 255.255.255.0
         !
         router bgp 65000
          address-family ipv4 unicast
           network 10.0.1.0/24
          neighbor 10.0.1.3
           remote-as 65000
           address-family ipv4 unicast

3. Verify

   1. RP/0/0/CPU0:R3#show bgp summ
      BGP router identifier 3.3.3.3, local AS number 65000
      Neighbor        Spk    AS MsgRcvd MsgSent   TblVer  InQ OutQ  Up/Down  St/PfxRcd
      10.0.0.2          0 65000       0       0        0    0    0 00:00:00 Active
      10.0.1.2          0 65000       6       6        6    0    0 00:02:50          3

   2. Notice that the 10.0.0.2 neighbor is stuck in Active. This is because iBGP requires a full-mesh topology to prevent routing loops.

IOS-XR Lab 6: iBGP with Three Routers part 2
IOS-XR Lab Index