Configure BGP

lab topology

     r2
    /  \
   /    \
r1  ---  r3

r1 is deltaos, r2, r3 are cisco ios.

r1
    ge0: 12.1.1.1/30
    ge1: 13.1.1.1/30
    lo0: 1.1.1.1/32

r2
    g0/0: 12.1.1.2/30
    g0/1: 23.1.1.1/30
    lo0: 2.2.2.2/32

r3
    g0/0: 13.1.1.2/30
    g0/1: 23.1.1.2/30
    lo0: 3.3.3.3/32

lab configuration

interface ge 0
  ip address 12.1.1.1 255.255.255.252
  no shutdown

interface ge 1
  ip address 13.1.1.1 255.255.255.252
  no shutdown

interface loopback 0
  ip address 1.1.1.1 255.255.255.255
  no shutdown

router bgp 65100
  address-family ipv4 unicast
    network 1.1.1.1 mask 255.255.255.255
  neighbor 12.1.1.2
    remote-as 65200
    address-family ipv4 unicast
  neighbor 13.1.1.2
    remote-as 65300
    address-family ipv4 unicast

interface loopback 0
  ip address 2.2.2.2 255.255.255.255
  no shutdown

interface GigabitEthernet0/0
 ip address 12.1.1.2 255.255.255.252
 no shutdown

interface GigabitEthernet0/1
 ip address 23.1.1.1 255.255.255.252
 no shutdown

router bgp 65200
 neighbor 12.1.1.1 remote-as 65100
 neighbor 23.1.1.2 remote-as 65300

 address-family ipv4
  network 2.2.2.2 mask 255.255.255.255
  neighbor 12.1.1.1 activate
  neighbor 23.1.1.2 activate
 exit-address-family

interface loopback 0
  ip address 3.3.3.3 255.255.255.255
  no shutdown

interface GigabitEthernet0/0
 ip address 13.1.1.2 255.255.255.252
 no shutdown

interface GigabitEthernet0/1
 ip address 23.1.1.2 255.255.255.252
 no shutdown

router bgp 65300
 bgp log-neighbor-changes
 neighbor 13.1.1.1 remote-as 65100
 neighbor 23.1.1.1 remote-as 65200

 address-family ipv4
  network 3.3.3.3 mask 255.255.255.255
  neighbor 13.1.1.1 activate
  neighbor 23.1.1.1 activate
 exit-address-family

check result

r1# show ip bgp
Status codes: * valid, > best, r RIB-failure
Origin codes: i - IGP, e - EGP, ? - incomplete

              Network        Next Hop     Metric     LocPrf Weight Path
 *>        1.1.1.1/32         0.0.0.0          0             32768 i
 *>        2.2.2.2/32        12.1.1.2          0          0      0 65200 i
 *                           13.1.1.2          0          0      0 65300 65200 i
 *>        3.3.3.3/32        13.1.1.2          0          0      0 65300 i
 *                           12.1.1.2          0          0      0 65200 65300 i

r2#show ip bgp
BGP table version is 4, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
              x best-external, a additional-path, c RIB-compressed,
              t secondary path,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *    1.1.1.1/32       23.1.1.2                               0 65300 65100 i
 *>                    12.1.1.1                               0 65100 i
 *>   2.2.2.2/32       0.0.0.0                  0         32768 i
 *    3.3.3.3/32       12.1.1.1                               0 65100 65300 i
 *>                    23.1.1.2                 0             0 65300 i

r3#show ip bgp
BGP table version is 4, local router ID is 3.3.3.3
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
              x best-external, a additional-path, c RIB-compressed,
              t secondary path,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *    1.1.1.1/32       23.1.1.1                               0 65200 65100 i
 *>                    13.1.1.1                               0 65100 i
 *    2.2.2.2/32       13.1.1.1                               0 65100 65200 i
 *>                    23.1.1.1                 0             0 65200 i
 *>   3.3.3.3/32       0.0.0.0                  0         32768 i