A BGP peer group is a set of BGP peers with the same policies, the peer inherits all the configurations of the group when it is added to the peer group. In a large network where there are many BGP peers with the same policies, you need to run some commands repeatedly for each peer increasing the maintenance workload and possibility of configuration errors.

BGP peer groups can be used to combine the configuration of BGP neighbors using a template, common commands are applied to the group once and apply to all peers in the group. A BGP peer group reduces the load on system resources by allowing the routing table to be checked only once, and updates to be replicated to all peer group members instead of being done individually for each peer in the peer group.

In our HoVPN solution, we apply route import and export policies on BGP groups which simplifies the configuration. Check it out from this link: IPRAN HoVPN Configuration on Huawei

Topology Description

R1, R2, R3, and R4 are in AS 200 and we configure OSPF as the IGP. R5 is configured in AS 300. We configure a group ” INTERNAL” for iBGP peering on R1, R2 R3, and R4 with R4 as the RR. A group “EXTERNAL” is configured on R4 and R5 for EBGP peering. IP addresses of interfaces are assigned as shown in the topology above.

Configuration Steps

Step 1: Configure IP addresses on all the routers.

***********************************R1
interface GigabitEthernet0/0/0
 ip address 10.10.10.1 255.255.255.254
#
interface GigabitEthernet0/0/1
 ip address 10.10.10.4 255.255.255.254
#
interface LoopBack0
 ip address 1.1.1.1 255.255.255.255
#

*****************************R2
interface GigabitEthernet0/0/0
 ip address 10.10.10.7 255.255.255.254
#
interface GigabitEthernet0/0/1
 ip address 10.10.10.5 255.255.255.254
#
interface LoopBack0
 ip address 2.2.2.2 255.255.255.255
#

********************************R3
interface GigabitEthernet0/0/0
 ip address 10.10.10.6 255.255.255.254
#
interface GigabitEthernet0/0/1
 ip address 10.10.10.3 255.255.255.254
#
interface LoopBack0
 ip address 3.3.3.3 255.255.255.255
#

******************************R4
interface GigabitEthernet0/0/0
 ip address 10.10.10.2 255.255.255.254
#
interface GigabitEthernet0/0/1
 ip address 10.10.10.0 255.255.255.254
#
interface GigabitEthernet0/0/2
 ip address 172.200.200.0 255.255.255.254
#
interface LoopBack0
 ip address 6.6.6.6 255.255.255.255
#

*****************************R5
interface GigabitEthernet0/0/1
 ip address 172.200.200.1 255.255.255.254
#
interface LoopBack0
 ip address 7.7.7.7 255.255.255.255
#

Step 2: Configure OSPF in AS 200 and verify adjacency status on routers in AS 200.

*******************************R1
ospf 10 router-id 1.1.1.1
 area 0.0.0.0
  network 1.1.1.1 0.0.0.0
  network 10.10.10.0 0.0.0.1
  network 10.10.10.4 0.0.0.1
#

*****************************R2
ospf 10 router-id 2.2.2.2
 area 0.0.0.0
  network 2.2.2.2 0.0.0.0
  network 10.10.10.6 0.0.0.1
  network 10.10.10.4 0.0.0.1
#

*****************************R3
ospf 10 router-id 3.3.3.3
 area 0.0.0.0
  network 3.3.3.3 0.0.0.0
  network 10.10.10.2 0.0.0.1
  network 10.10.10.6 0.0.0.1
#

****************************R4
ospf 10 router-id 6.6.6.6
 area 0.0.0.0
  network 6.6.6.6 0.0.0.0
  network 10.10.10.0 0.0.0.1
  network 10.10.10.2 0.0.0.1
#

Step 3: Configure BGP peering on all the routers. We configure a group for iBGP for peering among R1, R2, R3, and R4 and another group for eBGP for peering between R4 and R5.

***********************************R1
bgp 200
 router-id 1.1.1.1
 group INTERNAL internal
 peer INTERNAL connect-interface LoopBack0
 peer 6.6.6.6 as-number 200
 peer 6.6.6.6 group INTERNAL
 #
 ipv4-family unicast
  undo synchronization
  peer INTERNAL enable
  peer 6.6.6.6 enable
  peer 6.6.6.6 group INTERNAL
#

**************************************R2
bgp 200
 router-id 2.2.2.2
 group INTERNAL internal
 peer INTERNAL connect-interface LoopBack0
 peer 6.6.6.6 as-number 200
 peer 6.6.6.6 group INTERNAL
 #
 ipv4-family unicast
  undo synchronization
  peer INTERNAL enable
  peer 6.6.6.6 enable
  peer 6.6.6.6 group INTERNAL
#

************************************R3
bgp 200
 router-id 3.3.3.3
 group INTERNAL internal
 peer INTERNAL connect-interface LoopBack0
 peer 6.6.6.6 as-number 200
 peer 6.6.6.6 group INTERNAL
 #
 ipv4-family unicast
  undo synchronization
  peer INTERNAL enable
  peer 6.6.6.6 enable
  peer 6.6.6.6 group INTERNAL
#

****************************R4
bgp 200
 router-id 6.6.6.6
 group EXTERNAL external
 peer 172.200.200.1 as-number 300
 peer 172.200.200.1 group EXTERNAL
 group INTERNAL internal
 peer INTERNAL connect-interface LoopBack0
 peer 1.1.1.1 as-number 200
 peer 1.1.1.1 group INTERNAL
 peer 2.2.2.2 as-number 200
 peer 2.2.2.2 group INTERNAL
 peer 3.3.3.3 as-number 200
 peer 3.3.3.3 group INTERNAL
 #
 ipv4-family unicast
  undo synchronization
  peer EXTERNAL enable
  peer 172.200.200.1 enable
  peer 172.200.200.1 group EXTERNAL
  peer INTERNAL enable
  peer INTERNAL reflect-client
  peer INTERNAL next-hop-local
  peer 1.1.1.1 enable
  peer 1.1.1.1 group INTERNAL
  peer 2.2.2.2 enable
  peer 2.2.2.2 group INTERNAL
  peer 3.3.3.3 enable
  peer 3.3.3.3 group INTERNAL
#

*****************************R5
bgp 300
 router-id 7.7.7.7
 group EXTERNAL external
 peer 172.200.200.0 as-number 200
 peer 172.200.200.0 group EXTERNAL
 #
 ipv4-family unicast
  undo synchronization
  peer EXTERNAL enable
  peer 172.200.200.0 enable
  peer 172.200.200.0 group EXTERNAL
#

Step 4: Verify BGP peering status.