Example for Configuring BGP to Interact with an IGP

Configuring BGP to interact with an IGP can enrich routing tables.

Networking Requirements

As the Internet grows, devices in different networks need to access each other, data needs to be reliably transmitted, and the traffic interruption time needs to be minimized. This requires that routing information be transmitted widely and network convergence be accelerated. BGP can transmit routing information efficiently and widely. BGP, however, does not calculate routes by itself. An IGP can implement rapid route convergence, but it transmits routing information with a low efficiency in a limited scope. After BGP is configured to interact with an IGP, IGP routes can be imported into BGP routing tables and transmitted efficiently. BGP routes can also be imported into IGP routing tables to allow access to other ASs.

The network shown in Figure 1 is divided into AS 65008 and AS 65009. In AS 65009, an IGP is used to calculate routes. In this example, OSPF is used as an IGP. BGP can be configured to enable the two ASs to access each other. Interaction between BGP and the IGP can be configured on edge routers of the two ASs so that the two ASs can exchange routes efficiently. In addition, AS external routes can be imported into the IGP routing table to allow access to the outside of the local AS.

Figure 1 Configuring BGP to interact with an IGP

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



Precautions

None.

Configuration Roadmap

The configuration roadmap is as follows:

  1. Configure OSPF on Device B and Device C.

  2. Establish an EBGP connection between Device A and Device B.

  3. Configure BGP and OSPF to import routes from each other on Device B and then check the routes.

  4. Configure BGP route summarization on Device B to simplify the BGP routing table.

Data Preparation

To complete the configuration, you need the following data:

  • Router ID and AS number of Device A

  • Router IDs and AS numbers of Device B and Device C

Procedure

  1. Configure an IP address for each interface. For configuration details, see Configuration Files in this section.
  2. Configure OSPF.

    # Configure Device B.

    [~DeviceB] ospf 1
[*DeviceB-ospf-1] area 0
[*DeviceB-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[*DeviceB-ospf-1-area-0.0.0.0] commit
[~DeviceB-ospf-1-area-0.0.0.0] quit
[~DeviceB-ospf-1] quit

    # Configure Device C.

    [~DeviceC] ospf 1
[*DeviceC-ospf-1] area 0
[*DeviceC-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[*DeviceC-ospf-1-area-0.0.0.0] network 10.1.2.0 0.0.0.255
[*DeviceC-ospf-1-area-0.0.0.0] commit
[~DeviceC-ospf-1-area-0.0.0.0] quit
[~DeviceC-ospf-1] quit

  3. Configure an EBGP connection.

    # Configure Device A.

    [~DeviceA] bgp 65008
[*DeviceA-bgp] router-id 1.1.1.1
[*DeviceA-bgp] peer 172.16.1.1 as-number 65009
[*DeviceA-bgp] ipv4-family unicast
[*DeviceA-bgp-af-ipv4] network 192.168.1.0 255.255.255.0
[*DeviceA-bgp-af-ipv4] commit

    # Configure Device B.

    [~DeviceB] bgp 65009
[*DeviceB-bgp] router-id 2.2.2.2
[*DeviceB-bgp] peer 172.16.1.2 as-number 65008
[*DeviceB-bgp] commit

  4. Configure BGP to interact with an IGP.

    # Configure BGP to import OSPF routes on Device B.

    [~DeviceB-bgp] ipv4-family unicast
[*DeviceB-bgp-af-ipv4] import-route ospf 1
[*DeviceB-bgp-af-ipv4] commit
[~DeviceB-bgp-af-ipv4] quit
[~DeviceB-bgp] quit

    # Check the routing table of Device A.

    [~DeviceA] display bgp routing-table
 BGP Local router ID is 1.1.1.1
 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: 3
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn
 *>   192.168.1.0/24     0.0.0.0         0                     0      i
 *>   10.1.1.0/24        172.16.1.1      1                     0      65009?
 *>   10.1.2.0/24        172.16.1.1      2                     0      65009?

    # Configure OSPF to import BGP routes on Device B.

    [~DeviceB] ospf
[*DeviceB-ospf-1] import-route bgp
[*DeviceB-ospf-1] commit
[~DeviceB-ospf-1] quit

    # Check the routing table of Device C.

    [~DeviceC] display ip routing-table
Route Flags: R - relay, D - download to fib, T - to vpn-instance, B - black hole route
------------------------------------------------------------------------------
Routing Table : _public_
         Destinations : 12        Routes : 12

Destination/Mask    Proto  Pre  Cost        Flags NextHop         Interface

    192.168.1.0/24  O_ASE  150  1             D  10.1.1.1        GigabitEthernet0/1/0
       10.1.1.0/24  Direct 0    0             D  10.1.1.2        GigabitEthernet0/1/0
       10.1.1.1/32  Direct 0    0             D  10.1.1.1        GigabitEthernet0/1/0
       10.1.1.2/32  Direct 0    0             D  127.0.0.1       GigabitEthernet0/1/0
     10.1.1.255/32  Direct 0    0             D  127.0.0.1       GigabitEthernet0/1/0
       10.1.2.0/24  Direct 0    0             D  10.1.2.1        GigabitEthernet0/1/8
       10.1.2.1/32  Direct 0    0             D  127.0.0.1       GigabitEthernet0/1/8
     10.1.2.255/32  Direct 0    0             D  127.0.0.1       GigabitEthernet0/1/8
      127.0.0.0/8   Direct 0    0             D  127.0.0.1       InLoopBack0
      127.0.0.1/32  Direct 0    0             D  127.0.0.1       InLoopBack0
127.255.255.255/32  Direct 0    0             D  127.0.0.1       InLoopBack0
255.255.255.255/32  Direct 0    0             D  127.0.0.1       InLoopBack0

  5. Configure automatic route summarization.

    # Configure Device B.

    [~DeviceB] bgp 65009
[*DeviceB-bgp] ipv4-family unicast
[*DeviceB-bgp-af-ipv4] summary automatic
[*DeviceB-bgp-af-ipv4] commit

    # Check the BGP routing table of Device A.

    [~DeviceA] display bgp routing-table
 BGP Local router ID is 1.1.1.1
 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: 2
      Network            NextHop        MED        LocPrf    PrefVal Path/Ogn
 *>   192.168.1.0/24     0.0.0.0         0                     0      i
 *>   10.0.0.0           172.16.1.1                            0      65009?

    # Verify the configuration by using the ping command.

    [~DeviceA] ping -a 192.168.1.1 10.1.2.1
  PING 10.1.2.1: 56  data bytes, press CTRL_C to break
    Reply from 10.1.2.1: bytes=56 Sequence=1 ttl=254 time=15 ms
    Reply from 10.1.2.1: bytes=56 Sequence=2 ttl=254 time=31 ms
    Reply from 10.1.2.1: bytes=56 Sequence=3 ttl=254 time=47 ms
    Reply from 10.1.2.1: bytes=56 Sequence=4 ttl=254 time=46 ms
    Reply from 10.1.2.1: bytes=56 Sequence=5 ttl=254 time=47 ms
  --- 10.1.2.1 ping statistics ---
    5 packet(s) transmitted
    5 packet(s) received
    0.00% packet loss
    round-trip min/avg/max = 15/37/47 ms

Configuration Files

  • Device A configuration file

    #
sysname DeviceA
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 192.168.1.1 255.255.255.0
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 172.16.1.2 255.255.255.0
#
bgp 65008
 router-id 1.1.1.1
 peer 172.16.1.1 as-number 65009
 #
 ipv4-family unicast
  undo synchronization 
  network 192.168.1.0 255.255.255.0
  peer 172.16.1.1 enable
#
return

  • Device B configuration file

    #
sysname DeviceB
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.1 255.255.255.0
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 172.16.1.1 255.255.255.0
#
bgp 65009
 router-id 2.2.2.2
 peer 172.16.1.2 as-number 65008
 #
 ipv4-family unicast
  undo synchronization 
  summary automatic
  import-route ospf 1
  peer 172.16.1.2 enable
#
ospf 1
 import-route bgp
 area 0.0.0.0
  network 10.1.1.0 0.0.0.255
#
return

  • Device C configuration file

    #
sysname DeviceC
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 10.1.1.2 255.255.255.0
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 10.1.2.1 255.255.255.0
#
ospf 1
 area 0.0.0.0
  network 10.1.1.0 0.0.0.255
  network 10.1.2.0 0.0.0.255
#
return
Parent Topic: Configuration Examples for BGP
Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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