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VPN Traffic Generation


Alternatively, you may add demands within the VPNs using the VPN Traffic Generation tool. Select Tools > VPN Traffic Generation to open the window as shown in Figure 1.

Figure 1: VPN Traffic Generation
VPN Traffic Generation
  1. Select, in the VPN table, one or more VPNs for which you wish to generate demands.
  2. Next, specify the traffic source to use for the gravity model (either the Configured Interface BW or the Interface Traffic Load). The Interface Traffic Load corresponds to the egress/ingress files in the File > Load Network Files window, and the interfaceLoad_out and interfaceLoad_in files in the specification file. If selecting the Interface Traffic Load, select which period to use (Mean, Peak, or specific period.)
  3. Specify the subscription ratio in percentages in the L3/L2K/VPLS and L2M/L2CCC textboxes. The subscription ratio is a percentage of the router’s PE-CE interface bandwidth utilized for VPN traffic. The formula used to calculate the demand is dependent on the type of VPN that is being applied.

    Layer 3 VPN, Layer 2 Kompella VPN, or VPLS (Juniper) VPN

    gravity model is used to create a set of fully-meshed demands for this type of VPN. The program takes the configured interface bandwidth of all the interfaces in the routers and calculates a bandwidth for the circuits using a gravity formula. If the subscription ratio is not specified, the default value is 10%.

    Gravity model:

    1. For each router in the VPN, add up the traffic load of all of the interfaces that are associated with the VPN. This is the weight of the router.

    2. Let Wi be the weight of router i. Then the traffic from router i to router j is Wi * Wj / (-Wi + W1+W2...Wn), where n is the number of routers in the VPN.

    3. The bandwidth of the demand is calculated by multiplying the result of the previous step by the subscription ratio.

    Layer 2 Martini VPN or Layer 2 CCC VPN

    One demand is generated for each circuit that belongs in this type of VPN. The bandwidth of the demand is based on the interface bandwidth multiplied by the percentage specified by the user in the subscription ratio field. If the subscription ratio is not specified, the default value is 10%.

  4. “Generate demand between nodes instead of interfaces” can be selected to generate node-to-node demands instead of interface-to-interface demands. In this case, demands are aggregated so that only one demand is generated from nodeA to nodeB, instead of generating multiple demands from all interfaces on nodeA to all interfaces on nodeB
  5. Specify the demand file name. This can be an existing demand file, or the program will create the file if it does not already exist.
  6. If you are using an existing demand file, click on a radio button to select whether you wish to append the new demands, or overwrite the file with the new demands. Note: If the demand file specified in the Demand file name textbox does not exist, then either one of these selections will create the file for you.
  7. Click on the Generate Demands button to generate a set of demands for the VPNs selected. The generated demands will have uniquely assigned names and assigned with the owner of the VPN that it belongs to.
  8. Use the File Manager to view the new demands in the specified demand file.
  9. To import the new demands into the network model, open the File > Load Network Files window and select the generated demand file in the “newdemand” field.