Splitting a Flow into Sub-Flows
- Switch to Modify mode and select Modify > Elements > Demands... to bring up the Demands window. Double-click the flow you want to modify (or select the flow and select Modify > Selected...) to bring up the Modify Demand window.
- Click the Type button to bring up the Demand Type Parameter Generation Window as shown in Figure 1. 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.
- Notice the new value in the Type field in Figure 2.
- Switch back to View mode and select Network > Elements > Demands to bring up the Demands window. Sub-flows are displayed differently in the Type column in View mode, as shown in Figure 3. Rn means that n sub-flows share the same routing path. In this example, the original flow called flow10 was divided into 3 flows on the first ECMP and 2 flows on the second ECMP. The first entry for flow10 also says “ECMP=5”, to indicate that 5 subflows were created from the original flow. The second entry for flow10 also contains a special keyword, “ECMPN” or “ECMP2”. “ECMPN” is simply a reserved keyword used by the program to identify subflows that are associated with another “original” flow but whose routing path is different. To elaborate, if there were three different ECMP’s, then there would be three entries for flow10; the first would indicate “ECMP=n” and the latter two would show special keyword “ECMPN”. This simply helps the program associate these subflows with one another.
- Open the ECMP Report again in the Report Manager. This
time it will display the newly created ECMP demands in the report.
Although there are several discrete ECMP subflows (i.e. 5 in this example, 2 routing one way and 3 routing another), and technically the program could report an ECMP comparing each of the 2 with each of the 3, such information is not very useful. Therefore, the ECMP report only reports a single entry for flow10, comparing the two different routing paths.