BGP Scenario

ccnp-routing

Full lab scenario building eBGP and iBGP peerings across three autonomous systems, injecting routes, and verifying neighbor and BGP table state.

Published

Jan 21, 2018

Lab Files Download

Everything this lab needs, ready to download.

bgp-running-config.txt (8 KB), the full running configurations of the routers in this scenario

Base configuration R1:

hostname R1
!
interface Loopback0
 ip address 1.1.1.1 255.255.255.255
!
interface GigabitEthernet0/2
 ip address 12.12.12.1 255.255.255.0
!
interface GigabitEthernet0/3
 ip address 13.13.13.1 255.255.255.0
!
router ospf 1
 network 1.1.1.1 0.0.0.0 area 0
 network 12.12.12.1 0.0.0.0 area 0
 network 13.13.13.1 0.0.0.0 area 0

R2:

hostname R2
!
interface Loopback0
 ip address 2.2.2.2 255.255.255.255
!
interface GigabitEthernet0/0
 ip address 10.1.24.2 255.255.255.248
!
interface GigabitEthernet0/1
 ip address 12.12.12.2 255.255.255.0
!
interface GigabitEthernet0/2
 ip address 10.1.25.2 255.255.255.248
!
router ospf 1
 network 2.2.2.2 0.0.0.0 area 0
 network 12.12.12.2 0.0.0.0 area 0

R3:

hostname R3
!
interface Loopback0
 ip address 3.3.3.3 255.255.255.255
!
interface GigabitEthernet0/1
 ip address 13.13.13.3 255.255.255.0
!
interface GigabitEthernet0/3
 ip address 10.1.36.3 255.255.255.248
!
router ospf 1
 network 3.3.3.3 0.0.0.0 area 0
 network 13.13.13.3 0.0.0.0 area 0

R4:

hostname R4
!
interface Loopback0
 ip address 4.4.4.4 255.255.255.255
!
interface GigabitEthernet0/0
 ip address 45.45.45.4 255.255.255.0
!
interface GigabitEthernet0/2
 ip address 10.1.24.4 255.255.255.248
!
router eigrp R4
 !
 address-family ipv4 unicast autonomous-system 1
  !
  topology base
  exit-af-topology
  network 4.4.4.4 0.0.0.0
  network 45.45.45.4 0.0.0.0
 exit-address-family

R5:

hostname R5
!
interface Loopback0
 ip address 5.5.5.5 255.255.255.255
!
interface GigabitEthernet0/0
 ip address 45.45.45.5 255.255.255.0
!
interface GigabitEthernet0/2
 ip address 10.1.25.5 255.255.255.248
!
interface GigabitEthernet0/3
 ip address 10.1.56.5 255.255.255.248
!
router eigrp R5
 !
 address-family ipv4 unicast autonomous-system 1
  !
  topology base
  exit-af-topology
  network 5.5.5.5 0.0.0.0
  network 45.45.45.5 0.0.0.0
 exit-address-family

R6:

hostname R6
!
interface Loopback0
 ip address 6.6.6.6 255.255.255.255
!
interface GigabitEthernet0/0
 ip address 10.1.36.6 255.255.255.248
!
interface GigabitEthernet0/1
 ip address 160.160.160.6 255.255.255.0
!
interface GigabitEthernet0/3
 ip address 10.1.56.6 255.255.255.248

BGP neighborship configuration

R1:

R1(config)#router bgp 64500
R1(config-router)#neighbor 2.2.2.2 remote-as 64500
R1(config-router)#neighbor 2.2.2.2 next-hop-self
R1(config-router)#neighbor 2.2.2.2 update-source loopback 0
R1(config-router)#neighbor 3.3.3.3 remote-as 64500         
R1(config-router)#neighbor 3.3.3.3 next-hop-self
R1(config-router)#neighbor 3.3.3.3 update-source loopback 0

R2:

R2(config)#ip route 4.4.4.4 255.255.255.255 10.1.24.4
R2(config)#ip route 5.5.5.5 255.255.255.255 10.1.25.5
R2(config)#router bgp 64500
R2(config-router)#neighbor 4.4.4.4 remote-as 64510
R2(config-router)#neighbor 4.4.4.4 ebgp-multihop 2
R2(config-router)#neighbor 4.4.4.4 update-source loopback 0
R2(config-router)#neighbor 5.5.5.5 remote-as 64510
R2(config-router)#neighbor 5.5.5.5 ebgp-multihop 2
R2(config-router)#neighbor 5.5.5.5 update-source loopback 0
R2(config-router)#neighbor 1.1.1.1 remote-as 64500
R2(config-router)#neighbor 1.1.1.1 next-hop-self
R2(config-router)#neighbor 1.1.1.1 update-source loopback 0
R2(config-router)#neighbor 3.3.3.3 remote-as 64500
R2(config-router)#neighbor 3.3.3.3 next-hop-self
R2(config-router)#neighbor 3.3.3.3 update-source loopback 0

R3:

R3(config)#ip route 6.6.6.6 255.255.255.255 10.1.36.6
R3(config)#router bgp 64500
R3(config-router)#neighbor 6.6.6.6 remote-as 64520
R3(config-router)#neighbor 6.6.6.6 ebgp-multihop 2
R3(config-router)#neighbor 6.6.6.6 update-source loopback 0
R3(config-router)#neighbor 1.1.1.1 remote-as 64500
R3(config-router)#neighbor 1.1.1.1 next-hop-self
R3(config-router)#neighbor 1.1.1.1 update-source loopback 0
R3(config-router)#neighbor 2.2.2.2 remote-as 64500         
R3(config-router)#neighbor 2.2.2.2 next-hop-self
R3(config-router)#neighbor 2.2.2.2 update-source loopback 0

R4:

R4(config)#ip route 2.2.2.2 255.255.255.255 10.1.24.2
R4(config)#router bgp 64510
R4(config-router)#neighbor 2.2.2.2 remote-as 64500
R4(config-router)#neighbor 2.2.2.2 ebgp-multihop 2
R4(config-router)#neighbor 2.2.2.2 update-source loopback 0
R4(config-router)#neighbor 5.5.5.5 remote-as 64510
R4(config-router)#neighbor 5.5.5.5 next-hop-self 
R4(config-router)#neighbor 5.5.5.5 update-source loopback 0

R5:

R5(config)#ip route 2.2.2.2 255.255.255.255 10.1.25.2
R5(config)#ip route 6.6.6.6 255.255.255.255 10.1.56.6
R5(config)#router bgp 64510
R5(config-router)#neighbor 2.2.2.2 remote-as 64500
R5(config-router)#neighbor 2.2.2.2 ebgp-multihop 2
R5(config-router)#neighbor 2.2.2.2 update-source loopback 0
R5(config-router)#neighbor 6.6.6.6 remote-as 64520         
R5(config-router)#neighbor 6.6.6.6 ebgp-multihop 2
R5(config-router)#neighbor 6.6.6.6 update-source loopback 0
R5(config-router)#neighbor 4.4.4.4 remote-as 64510
R5(config-router)#neighbor 4.4.4.4 next-hop-self 
R5(config-router)#neighbor 4.4.4.4 update-source loopback 0

R6:

R6(config)#ip route 5.5.5.5 255.255.255.255 10.1.56.5
R6(config)#ip route 3.3.3.3 255.255.255.255 10.1.36.3
R6(config)#router bgp 64520
R6(config-router)#neighbor 3.3.3.3 remote-as 64500
R6(config-router)#neighbor 3.3.3.3 ebgp-multihop 2
R6(config-router)#neighbor 3.3.3.3 update-source loopback 0
R6(config-router)#neighbor 5.5.5.5 remote-as 64510
R6(config-router)#neighbor 5.5.5.5 ebgp-multihop 2
R6(config-router)#neighbor 5.5.5.5 update-source loopback 0

BGP injecting routes

R1(config)#router bgp 64500
R1(config-router)#network 13.13.13.0 mask 255.255.255.0
R1(config-router)#network 12.12.12.0 mask 255.255.255.0

R2(config)#router bgp 64500
R2(config-router)#network 12.12.12.0 mask 255.255.255.0

R3(config)#router bgp 64500
R3(config-router)#network 13.13.13.0 mask 255.255.255.0

R4(config)#router bgp 64510
R4(config-router)#network 45.45.45.0 mask 255.255.255.0

R5(config)#router bgp 64510
R5(config-router)#network 45.45.45.0 mask 255.255.255.0

R6(config)#ip prefix-list LAN160 permit 160.160.160.0/24
R6(config)#route-map RDtoBGP permit                     
R6(config-route-map)#match ip address prefix-list LAN160
R6(config-route-map)#exit
R6(config)#router bgp 64520
R6(config-router)#redistribute connected route-map RDtoBGP

Some verification

R6#show ip bgp   
BGP table version is 7, local router ID is 6.6.6.6
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, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *   12.12.12.0/24    5.5.5.5                                0 64510 64500 i
 *>                   3.3.3.3                                0 64500 i
 *   13.13.13.0/24    5.5.5.5                                0 64510 64500 i
 *>                   3.3.3.3                  0             0 64500 i
 *   45.45.45.0/24    3.3.3.3                                0 64500 64510 i
 *>                   5.5.5.5                  0             0 64510 i
 *>  160.160.160.0/24 0.0.0.0                  0         32768 ?

? means the route is injected into BGP by the redistribution command
i means the route is injected into BGP by the network command

R2’s BGP neighbors

R2#show ip bgp summary 
BGP router identifier 2.2.2.2, local AS number 64500
BGP table version is 8, main routing table version 8
4 network entries using 576 bytes of memory
9 path entries using 720 bytes of memory
5/4 BGP path/bestpath attribute entries using 760 bytes of memory
3 BGP AS-PATH entries using 72 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 2128 total bytes of memory
BGP activity 4/0 prefixes, 10/1 paths, scan interval 60 secs

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
1.1.1.1         4        64500     179     180        8    0    0 02:38:37        2
3.3.3.3         4        64500     175     170        8    0    0 02:31:52        2
4.4.4.4         4        64510     333     332        8    0    0 04:56:53        2
5.5.5.5         4        64510     195     191        8    0    0 02:50:30        2

R2’s BGP topology table

R2#show ip bgp         
BGP table version is 8, local router ID is 2.2.2.2
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, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *>  12.12.12.0/24    0.0.0.0                  0         32768 i
 * i                  1.1.1.1                  0    100      0 i
 r i 13.13.13.0/24    3.3.3.3                  0    100      0 i
 r>i                  1.1.1.1                  0    100      0 i
 *   45.45.45.0/24    4.4.4.4                  0             0 64510 i
 *>                   5.5.5.5                  0             0 64510 i
 *   160.160.160.0/24 5.5.5.5                                0 64510 64520 ?
 *                    4.4.4.4                                0 64510 64520 ?
 *>i                  3.3.3.3                  0    100      0 64520 ?

R2’s routing table for BGP

R2#show ip route bgp
Gateway of last resort is not set

      45.0.0.0/24 is subnetted, 1 subnets
B        45.45.45.0 [20/0] via 5.5.5.5, 01:39:25
      160.160.0.0/24 is subnetted, 1 subnets
B        160.160.160.0 [200/0] via 3.3.3.3, 00:13:34