Home BGP Configurations Cisco

Border Gateway Protocol (BGP) is one of the major protocols to achieve WAN connection redundancy. When you connect your network to Internet, BGP will be the easiest choice. Especially with two different Internet service providers (ISPs), BGP would be the only protocol you can choose.

Simple Cisco BGP Configuration by topology


I believe that the below topologies would cover the most of BGP configurations in real life. However, If you need a configuration for more specific topology, please send email me at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

The information in this article is based on Cisco Routers and GNS3 simulation tool. And used Cisco IOS® Software Release 12.x(x) and above.

Also, the BGP sample configuration were created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

We strongly recommend you to create a lab before applying prospective BGP configuration to production network.

 


BGP topology 1


  • ISPs : 1
  • WAN links : 1
  • CPE : 1
  • PE : 1

Sample configurations

1-1-1. Cisco Single BGP with default route
1-2-1.
Cisco Single BGP with Metric
1-3-1.
Cisco Single BGP with Origin value
1-4-1.
Cisco Single BGP with AS prepend
1-5-1.
Cisco Single BGP with Community string
1-6-1.
Cisco Single BGP with Multi-hop
1-7-1. Cisco Single BGP with MD5

BGP configuration topology 1

 

 

BGP topology 2

 
  • ISPs : 1
  • WAN links : 2
  • CPE : 1
  • PE : 1

Sample configurations

2-1-1. Cisco Single BGP with Multi-hop (load-balancing)
2-1-2. Cisco Single BGP with Multi-hop and eigrp(load-balancing)
2-2-1.
Cisco dual BGP with conditional announcement
2-3-1.
Cisco Single BGP with Multi-hop (load-balancing) on Ethernet using GRE Tunnel
2-3-2.
Cisco Multiple BGP with load-balancing on Ethernet using Maximum-paths
2-3-3. Cisco Multiple BGP with load-sharing using Maximum-paths and DMZLink-BW

BGP configuration topology 2

 

 

BGP topology 3

 
  • ISPs : 1
  • WAN links : 2
  • CPE : 1
  • PE : 2

Sample configurations

3-1-1. Cisco Dual BGP with Metric (Redundancy)
3-2-1.
Cisco Dual BGP with prefix Length (Load-balancing)
3-3-1.
Cisco Dual BGP with AS prepend (Redundancy)
3-3-2.
Cisco Dual BGP with AS prepend (Load-balancing)
3-4-1.
Cisco Dual BGP with Community string (Redundancy)
3-4-2.
Cisco Dual BGP with Community string (Load-balancing)
3-5-1.
Cisco Dual BGP with Origin Value (Redundancy)
3-6-1.
Cisco Dual BGP with Conditional Announcement

BGP configuration topology 3

 

 

BGP topology 4

 
  • ISPs : 2
  • WAN links : 2
  • CPE : 1
  • PE : 2

Sample configurations

4-1-1. Cisco dual BGP with Metric (Redundancy)
4-2-1.
Cisco dual BGP with prefix Length (Load-balancing)
4-3-1.
Cisco dual BGP with AS prepend (Redundancy)
4-3-2.
Cisco dual BGP with AS prepend (Load-balancing)
4-4-1.
Cisco dual BGP with Community string (Redundancy)
4-4-2.
Cisco dual BGP with Community string (Load-balancing)
4-5-1.
Cisco dual BGP with Origin Value (Redundancy)
4-5-2.
Cisco dual BGP with Origin Value (Load-balancing)
4-6-1.
Cisco dual BGP with Conditional Announcement
 

BGP configuration topology 4


BGP topology 5

 
  • ISPs : 1
  • WAN links : 2
  • CPE :2
  • PE : 2

Sample configurations

5-1-1. Cisco dual BGP with AS prepend-HSRP (Load-sharing)
5-1-2.
Cisco dual BGP with AS prepend-iBGP (Load-sharing)
5-2-1.
Cisco dual BGP with Community string-HSRP (Load-sharing)
5-2-2.
Cisco dual BGP with Community string-iBGP (Load-sharing) 
 

BGP configuration topology 5

 

 

BGP topology 6

 
  • ISPs : 2
  • WAN links : 2
  • CPE :2
  • PE : 2

Sample configurations

6-1-1. Cisco dual BGP with AS prepend-HSRP (Load-sharing)
6-1-2.
Cisco dual BGP with AS prepend-iBGP (Load-sharing)
6-2-1.
Cisco dual BGP with Community string-HSRP (Load-sharing)
6-2-2.
Cisco dual BGP with Community string-iBGP (Load-sharing)
6-3-1. Cisco dual BGP with AS prepend-RIP (Load-sharing)
6-4-1. Cisco dual BGP with AS prepend-eIGRP (Load-sharing)

 

BGP configuration topology 6

 

 

BGP topology 7

 
  • ISPs : 2
  • WAN links : 2
  • CPE :2
  • PE : 2

Sample configurations

7-1-1. Cisco dual BGP with eBGP (Failover)
7-2-1. Cisco dual BGP with RIP (Failover)
7-3-1. Cisco dual BGP with eIGRP (Failover)


 

BGP configuration topology 7

 

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Thank you! 

 

 
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