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Splitting a Flow into Sub-Flows

To create sub-flows, ensure that you have more than one equal-cost multipaths (ECMPs) between the source and destination. If you do not have ECMPs, between the source and destination, change the OSPF cost metrics of the links in one or more paths between the source and destination (Metrics field and the OSPF field in the Protocols tab of the Modify Link window (Link > Modify Link).

  1. From the Demands tab of Network Info table, double-click the flow you want to modify, or select the flow and click Modify > Selected...) to bring up the Modify Demand window.
  2. Click the Type button to bring up the Demand Type Parameter Generation Window as shown in Figure 1.
  3. Select the ECMP checkbox and enter the number of sub-flows desired. The default number of sub-flows is 6 if no value is entered, or it can be set based on the bandwidth using the ECMPcntByBW parameter. Then click OK.
    Figure 1: Demand Type Parameter Generation Window Demand Type Parameter Generation Window
  4. On the Design tab of the Demand Type Parameter window, set the Routing Method to OSPF and click OK.
    The Modify Demand window appears. Notice the new value in the Type field in the Properties tab is changed to R, RM=OSPF,ECMP=10. See Figure 2,
    Figure 2: Modify Demand Window Modify Demand Window
  5. Click OK to return to the Network Info table.

    Sub-flows are displayed differently in the Type column. The Figure 3 shows that the demand Flow 72 between Los Angeles and Houston is split into two flows—one flowing through Atlanta and the other through San Diego. ECMP=10 in the first row indicates that it is the original flow for the demand. 10 indicates that the original demand is split into 10 subflows. ECMPN in the second row indicates that it is the subflow. ECMPRatio=0.50 indicates that the original bandwidth of the demand (ECMPBW=10G) is split in the ratio of 0.5 between the two subflows.

    Figure 3: Demand Flow in ECMP Demand Flow in ECMP
  6. Open the ECMP Report in the Report Manager (Report > Report Manager > Network Reports > Demand Reports > Equal Cost Multi-Path) to view the newly created ECMP demands in the report.