Example for Configuring a BGP Confederation

BGP confederations can be used to reduce the number of IBGP connections.

Networking Requirements

If multiple devices are deployed in an AS and fully meshed IBGP connections must be implemented between every two devices in the AS, a large number of IBGP connections will be established, increasing operation and maintenance costs. To address this issue, configure BGP confederations.

On the network shown in Figure 1, configure confederations in AS 200 to reduce the number of IBGP connections to be established. After confederations are configured, AS 200 is divided into three sub-ASs: AS 65001, AS 65002, and AS 65003. AS 65001 establishes EBGP connections with AS 65002 and AS 65003. The three routers in AS 65001 establish IBGP fully meshed connections with each other.

Figure 1 Configuring the confederation

Interfaces 1 through 5 in this example represent GE 0/1/0, GE 0/1/8, GE 0/1/16, GE 0/1/1, and GE 0/1/2, respectively.


Configuration Roadmap

The configuration roadmap is as follows:

  1. Configure a BGP confederation on each router in AS 200.

  2. Configure the IBGP connection in AS 65001.

  3. Configure the EBGP connection between AS 100 and AS 200, and check the routes.

Data Preparation

To complete the configuration, you need the following data:

  • The Router IDs of DeviceA, DeviceB, DeviceC, DeviceD, DeviceE, and DeviceF (1.1.1.1, 2.2.2.2, 3.3.3.3, 4.4.4.4, 5.5.5.5, and 6.6.6.6)

  • The AS number (100), and the three sub-ASs of AS 200 (AS 65001, AS 65002, and AS 65003)

Procedure

  1. Assign an IP address to each interface.

    For configuration details, see Configuration Files in this section.

  2. Configure the BGP confederation.

    # Configure DeviceA.

    [~DeviceA] bgp 65001
[*DeviceA-bgp] router-id 1.1.1.1
[*DeviceA-bgp] confederation id 200
[*DeviceA-bgp] confederation peer-as 65002 65003
[*DeviceA-bgp] peer 10.1.1.2 as-number 65002 
[*DeviceA-bgp] peer 10.1.2.2 as-number 65003
[*DeviceA-bgp] ipv4-family unicast
[*DeviceA-bgp-af-ipv4] peer 10.1.1.2 next-hop-local
[*DeviceA-bgp-af-ipv4] peer 10.1.2.2 next-hop-local
[*DeviceA-bgp-af-ipv4] commit
[~DeviceA-bgp-af-ipv4] quit
[~DeviceA-bgp] quit

    # Configure DeviceB.

    [~DeviceB] bgp 65002
[*DeviceB-bgp] router-id 2.2.2.2
[*DeviceB-bgp] confederation id 200
[*DeviceB-bgp] confederation peer-as 65001
[*DeviceB-bgp] peer 10.1.1.1 as-number 65001
[*DeviceB-bgp] commit
[~DeviceB-bgp] quit

    # Configure DeviceC.

    [~DeviceC] bgp 65003
[*DeviceC-bgp] router-id 3.3.3.3
[*DeviceC-bgp] confederation id 200
[*DeviceC-bgp] confederation peer-as 65001
[*DeviceC-bgp] peer 10.1.2.1 as-number 65001
[*DeviceC-bgp] commit
[~DeviceC-bgp] quit

  3. Configure IBGP connections inside AS 65001.

    # Configure DeviceA.

    [~DeviceA] bgp 65001
[*DeviceA-bgp] peer 10.1.3.2 as-number 65001
[*DeviceA-bgp] peer 10.1.4.2 as-number 65001
[*DeviceA-bgp] ipv4-family unicast
[*DeviceA-bgp-af-ipv4] peer 10.1.3.2 next-hop-local
[*DeviceA-bgp-af-ipv4] peer 10.1.4.2 next-hop-local
[*DeviceA-bgp-af-ipv4] commit
[~DeviceA-bgp-af-ipv4] quit 
[~DeviceA-bgp] quit

    # Configure DeviceD.

    [~DeviceD] bgp 65001
[*DeviceD-bgp] router-id 4.4.4.4
[*DeviceD-bgp] confederation id 200
[*DeviceD-bgp] peer 10.1.3.1 as-number 65001
[*DeviceD-bgp] peer 10.1.5.2 as-number 65001
[*DeviceD-bgp] commit
[~DeviceD-bgp] quit

    # Configure DeviceE.

    [~DeviceE] bgp 65001
[*DeviceE-bgp] router-id 5.5.5.5
[*DeviceE-bgp] confederation id 200
[*DeviceE-bgp] peer 10.1.4.1 as-number 65001
[*DeviceE-bgp] peer 10.1.5.1 as-number 65001
[*DeviceE-bgp] commit
[~DeviceE-bgp] quit

  4. Configure the EBGP connection between AS 100 and AS 200.

    # Configure DeviceA.

    [~DeviceA] bgp 65001
[*DeviceA-bgp] peer 10.216.1.2 as-number 100 
[*DeviceA-bgp] commit
[~DeviceA-bgp] quit

    # Configure DeviceF.

    [~DeviceF] bgp 100
[*DeviceF-bgp] router-id 6.6.6.6
[*DeviceF-bgp] peer 10.216.1.1 as-number 200 
[*DeviceF-bgp] ipv4-family unicast
[*DeviceF-bgp-af-ipv4] network 192.168.1.0 255.255.255.0
[*DeviceF-bgp-af-ipv4] commit
[~DeviceF-bgp-af-ipv4] quit
[~DeviceF-bgp] quit

  5. Verify the configuration.

    # Check the routing table of DeviceB.

    [~DeviceB] display bgp routing-table
 BGP Local router ID is 2.2.2.2
 Status codes: * - valid, > - best, d - damped, x - best external, a - add path,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete
 RPKI validation codes: V - valid, I - invalid, N - not-found
 Total Number of Routes: 1
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn
 *>i  192.168.1.0/24     10.1.1.1        0          100        0      (65001) 100i
[~DeviceB] display bgp routing-table 192.168.1.0
BGP local router ID : 2.2.2.2
 Local AS number : 65002
 Paths:   1 available, 1 best, 1 select
 BGP routing table entry information of 192.168.1.0/24:
 From: 10.1.1.1 (1.1.1.1)
 Route Duration: 00h12m29s
 Relay IP Nexthop: 0.0.0.0
 Relay IP Out-Interface: GigabitEthernet0/1/0
 Original nexthop: 10.1.1.1
 Qos information : 0x0
 AS-path (65001) 100, origin igp, MED 0, localpref 100, pref-val 0, valid, external-confed, best, select, active, pre 255
 Not advertised to any peer yet

    # Check the BGP routing table of DeviceD.

    [~DeviceD] display bgp routing-table
 BGP Local router ID is 4.4.4.4
 Status codes: * - valid, > - best, d - damped, x - best external, a - add path,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete
 RPKI validation codes: V - valid, I - invalid, N - not-found
 Total Number of Routes: 1
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn
 *>i  192.168.1.0/24     10.1.3.1        0          100        0      100i
[~DeviceD] display bgp routing-table 192.168.1.0
BGP local router ID : 4.4.4.4
 Local AS number : 65001
 Paths:   1 available, 1 best, 1 select
 BGP routing table entry information of 192.168.1.0/24:
 From: 10.1.3.1 (1.1.1.1)
 Route Duration: 00h23m57s
 Relay IP Nexthop: 0.0.0.0
 Relay IP Out-Interface: GigabitEthernet0/1/0
 Original nexthop: 10.1.3.1
 Qos information : 0x0
 AS-path 100, origin igp, MED 0, localpref 100, pref-val 0, valid, internal-confed, best, select, active, pre 255
 Not advertised to any peer yet

Configuration Files

  • DeviceA configuration file

    #
sysname DeviceA
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.216.1.1 255.255.255.0
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 10.1.1.1 255.255.255.0
#
interface GigabitEthernet0/1/16
 undo shutdown
 ip address 10.1.2.1 255.255.255.0
#
interface GigabitEthernet0/1/1
 undo shutdown
 ip address 10.1.3.1 255.255.255.0
#
interface GigabitEthernet0/1/2
 undo shutdown
 ip address 10.1.4.1 255.255.255.0
#
bgp 65001
 router-id 1.1.1.1
 confederation id 200
 confederation peer-as 65002 65003
 peer 10.1.1.2 as-number 65002
 peer 10.1.2.2 as-number 65003
 peer 10.1.3.2 as-number 65001
 peer 10.1.4.2 as-number 65001
 peer 10.216.1.2 as-number 100
 #
 ipv4-family unicast
  undo synchronization 
  peer 10.216.1.2 enable
  peer 10.1.1.2 enable
  peer 10.1.1.2 next-hop-local
  peer 10.1.2.2 enable
  peer 10.1.2.2 next-hop-local
  peer 10.1.3.2 enable
  peer 10.1.3.2 next-hop-local
  peer 10.1.4.2 enable
  peer 10.1.4.2 next-hop-local
#
return

  • DeviceB configuration file

    #
sysname DeviceB
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.2 255.255.255.0
#
bgp 65002
 router-id 2.2.2.2
 confederation id 200
 confederation peer-as 65001
 peer 10.1.1.1 as-number 65001
 #
 ipv4-family unicast
  undo synchronization 
  peer 10.1.1.1 enable
#
return

    The configuration file of DeviceC is similar to that of DeviceB.

  • DeviceD configuration file

    #
sysname DeviceD
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.3.2 255.255.255.0
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 10.1.5.1 255.255.255.0
#
bgp 65001
 router-id 4.4.4.4
 confederation id 200
 peer 10.1.3.1 as-number 65001
 peer 10.1.5.2 as-number 65001
 #
 ipv4-family unicast
  undo synchronization 
  peer 10.1.3.1 enable
  peer 10.1.5.2 enable
#
return

    The configuration file of DeviceE is similar to that of DeviceD.

  • DeviceF configuration file

    #
sysname DeviceF
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.216.1.2 255.255.255.0
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 192.168.1.1 255.255.255.0
#
bgp 100
 router-id 6.6.6.6
 peer 10.216.1.1 as-number 200
 #
 ipv4-family unicast
  undo synchronization 
  network 192.168.1.0 255.255.255.0
  peer 10.216.1.1 enable
#
return
Parent Topic: Configuration Examples for BGP
Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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