Lab 8.4.3 Configure BGP Connectivity between 2 Autonomous Systems

Objective:

The student should be able to configure external BGP between multiple Autonomous Systems.

Task:

Router A is your corporate router. You are responsible for configuring the ISP routers as well as your corporate router and ensuring that users on the corporate network can see the Internet. For lab purposes, the Internet will be the Ethernet interfaces on each of the ISP routers.

Situation:

Your company is now dependent on e-commerce and has decided to have two connections to the Internet going to 2 different ISPs. Your ISP has informed you that you have to run BGP to make this work. The ISP has asked that you remove your static route to them, and configure a BGP route in order to ensure that everything is operation okay before you add the second ISP to the equation.

ISP #1 has an AS number of 200 while ISP #2 has an AS number of 400.

Addressing:
Router A: S0: 200.200.200.65/30
S1: 130.1.50.33/30
E0: 193.10.2.1/24

Router B: S0: 130.1.50.34/30
E0: 12.0.0.1/8

Router C: S1: 200.200.200.66/30
E0: 11.0.0.1/8

Overview of approach:

  1. Implement the IP addressing scheme as shown in the diagram.
  2. Enable BGP routing with AS number and assign neighbor relationship with ISP #1.
  3. Configure router B in ISP #1.
  4. Verify operation.
  5. Repeat sequence for ISP #2.
  6. Verify operation.

Steps:

  1. Configure all interfaces on all routers with the appropriate IP address and subnet mask. Don't forget to issue the no shutdown command as well!
  2. Go to Router A. Issue the show ip route command. Are there any routes in the routing table? If so, which ones?

  1. We are now going to configure BGP on the corporate router. This is Router A. · To turn on BGP routing, enter global configuration mode and issue the following command: routerA(config)# router bgp 300
  2. Verify that you can ping the IP address of the serial interface on Router B of ISP#1 from Router A.

Could you successfully ping the interface?

  1. The next step is to define BGP neighbors. To do this, return to the following mode and type the command below.

RouterA(config-router)# neighbor 130.1.50.34 remote-as 200

  1. Next step is to configure the locally attached networks that should be advertised from AS#300. To do this, issue the following command:

RouterA(config-router)#network 193.10.2.0

  1. Return to privileged mode and save your configuration.

CONFIGURE BGP ROUTING on ISP 1

  1. Enable BGP routing on Router B in ISP 1. To do this, issue the command:

RouterB(config)# router bgp 200

  1. Next step is to define the neighbor router(s) to ISP 1. Use the neighbor command like before.

RouterB(config-router)# neighbor 130.1.50.33 remote-as 300

  1. Final step for this half of the configuration is to define networks local to AS 200. Issue the following command:

RouterB(config-router)#network 12.0.0.0

Return to privileged mode and save your configuration.

Verify the BGP connection is working.

  1. Issue the show ip bgp neighbors command.

What is the BGP state?

How long has the connection been up for?

  1. Issue the show ip bgp command.

Does network 193.10.2.0 show up in the table?

What is the path to 193.10.2.0?

What does the path number represent?

Configure the BGP connection between Router A and Router C (ISP 2).

  1. Add additional neighbor information to Router A. Use the following command:

RouterA(config-router)#neighbor 200.200.200.66 remote-as 400

  1. Enable BGP on Router C. Use the following commands:

RouterC(config)# router bgp 400
RouterC(config-router)#neighbor 200.200.200.65 remote-as 300

  1. Indicate the networks that are found locally on AS 400. Use the following command:

RouterC(config-router)#network 11.0.0.0

Return to privileged mode and save your configuration.

  1. It is now time to reset the neighbor connections, and build a new BGP table. To do this, issue the command:

RouterA# clear ip bgp *

VERIFY THE CONFIGURATION

  1. From Router A, ping the Ethernet interfaces of Routers B and C.
  • Was the ping successful?

  1. Verify that BGP has a route to both Ethernet interfaces.
  • What command should you use?

  • Describe the results of this command:

  1. Verify that the IP routing table has the routes you are trying to access.
  • What command should you use?

  • Are the routes there?

  1. Use the ping command from ISP 1 and ISP 2 to verify that each ISP can get to your network without having a static route configured.