Lab aims

Getting the students familiar with L2 Virtual Private Networks powered by MPLS technology. The network is built using GNS3 emulator. It's understood that the student is already familiar with MPLS technology and that is why the details on setting up MPLS in the service provider's network are not presented. One can review the lab on setting up of MPLS if necessary.

Network scheme


Lab description

This lab emulates the service provider's network that offers L2 connectivity to its clients. L3 backbone network is powered by Cisco 7200 routers using MPLS technology. This lab emulates the procedure of maintaining connectivity between offices of two companies (A and B).

  1. Perform all connections presented on the scheme.
  2. Develop an address plan for the service provider's network and client networks.
  3. Assign the IP addresses to the routers' interfaces in the service provider's network and enable an internal dynamic routing protocol.
  4. Create Loopback 0 interfaces on all routers. Assign them IP addresses with /32 mask.
  5. Make sure that every router of the service provider has a route to every address assigned to Loopback 0 interfaces of the other routers.
  6. Enable MPLS inside of the service provider's network.
  7. Use xconnect ip_address vc_number encapsulation mpls command to enable xconnect support on the interface of ISP1 router which router A1 is connected to. Please note that ip_address stands for the IP address of Loopback 0 interface of ISP4 router, whilst vc_number is the value of MPLS label using which the traffic is to be transferred between A1 and A2 offices.
  8. Configure ISP4 router in the same way. vc_number attribute number must be equal on both sides.
  9. Use sho mpls l2transport vc and sho xconnect all commands in order to make sure that the xconnect virtual connection has been established completely on both routers of the service provider.
  10. Assign IP addresses to the necessary interfaces of client routers in company A. Use Loopback interfaces for emulation of local networks in the client offices. Interface addresses of A1 and A2 routers used for connection to the service provider must be in the same IP sub-network.
  11. Make sure that there is connectivity between A1 and A2 routers.
  12. Capture the frames that are transferred through ISP1-ISP2 and ISP1-ISP3 channels using Wireshark network analyser. Examine the frame structure and review all labels.
  13. Configure an internal dynamic routing protocol between the devices in company A. Redistribute information about the internal networks in both offices of the company into it.
  14. Make sure that the routing information is being successfully transferred between A1 and A2 devices.
  15. Make sure that there is connectivity between the networks in both offices of company A.
  16. The same way like for company A, establish L2 connectivity for company B. Connection of the company B offices to the service provider's network is done using serial interfaces.
  17. Check whether it's possible to establish L2 connectivity for two types of encapsulation used on the serial interfaces: HDLC and PPP. Naturally, the selected encapsulation must be the same on both link edges. One may need to repeat the procedure of setting-up xconnect upon changing encapsulation on the serial interfaces.
  18. Configure Frame-Relay encapsulation on the client routers in company B and perform all other settings necessary for operation of this channel protocol.
  19. Configure HDLC encapsulation on the respective interfaces of the service provider's routers.
  20. Use ping command, which should be performed on the client routers, to make sure that the data between B1 and B2 devices are being transferred successfully.
  21. Configure OSPF dynamic routing protocol on B1 and B2 routers for exchange of prefixes between the offices of company B. Upon configuring OSPF one needs to consider its operation peculiarities in Frame-Relay (NBMA) networks.
  22. Make sure that the routing info between B1 and B2 devices are being transferred successfully.
  23. Make sure that the traffic is being successfully transferred between the local networks in company B.

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