NorthStar Planner Equal Cost Multiple Paths Overview

This chapter describes several Equal Cost Multiple-Paths (ECMP) features and walks through a scenario where it is useful. You will be able to display all the equal cost multiple-paths in the network as well as view any equal cost paths between two given nodes in detail. You can also split flows into sub-flows. Note that parallel links between two nodes do not count towards ECMPs.

When modelling ECMP routing, you set a point-to-point demand to type ECMP. When set to ECMP, the demand is split into a number of sub-flows and routed independently and the sub-flows which end up having the same path are recombined. The number of sub-flows can be either set explicitely on the main demand definition (ECMP=10), or if only tagged as ECMP (that is, you do not specify the number of sub-flows), the number of sub-flows is determined by the demand bandwidth and the settings defined for ECMP path placement (Design > Design Options > Path Placement > ECMP).

The Report Manager (Report > Report Manager > Network Reports > Demand Reports > Equal Cost Multi-Path) provides a report of all the ECMPs in your network.

Sometimes it is desirable to reduce the number of ECMPs in order to improve the predictability of how demands will be routed in the network. At other times it is desirable to split flows into sub-flows with ECMPs in order to perform load balancing. Paragon Planner will place these flows on routing paths that have identical costs.

For an overview of NorthStar Planner or for a detailed description of each feature and the use of each window, refer to the NorthStar Planner Desktop Application User Guide.