Impact analysis simulation overview

Introduction

The CPAM allows you to create a simulated network topology to test the impact of changes to the simulated network on existing IP paths. An IP path represent one or more GRE or LDP tunnels of the same source and destination. In addition, the CPAM supports RSVP LSP simulation.

The simulated topology—or scenario—can be an OSPF or ISIS network in an IGP administrative domain. The simulated network allows you to analyze the impact of typical network changes, such as the following:

• changes to the status of a router, such as:

  • turn up

  • shutdown

  • add

  • delete (not recommended)

• changes to the status of a link, such as:

  • turn up

  • shutdown

  • add

  • delete (not recommended)

• changes to the configuration of a link, such as:

  • total bandwidth and available bandwidth

  • administrative groups

  • metric (cost)

  • changes to LSP measured bandwidth, to see impacts on link utilization

The simulated topology has four modes of operation that are indicated in the top-left corner of the topology map:

• Topology being modified (yellow indicator)

  The topology is in this mode of operation when a change is made to the topology.

• Analyzing impact (blue indicator)

  The topology is in this mode of operation when you click on the Impact Analysis button after modifying the topology, and indicates that the CPAM is analyzing the topology changes and determining the impact on path monitors.

• Topology converged (grey indicator)

  The topology is in this mode of operation after an impact analysis has been performed. You can perform SPF and CSPF highlight operations only when the topology is in this mode of operation.

• Importing (blue indicator)

  The topology is in this mode of operation when you import objects into the impact analysis scenario.

When you change a network object attribute, or add or delete a simulated object, the operation mode indicator on the simulated topology changes from Topology converged to Topology being modified. When the topology is converged after you start the impact analysis by clicking on the Impact Analysis button, you can perform the following functions on the converged topology:

• calculate SPF

• calculate CSPF

• monitor IP paths

You can create a scenario manually, or populate a scenario from a checkpoint, the real network, or from an existing scenario. Only two scenario sessions can be active at the same time. You need the topology simulation scope of command to use the impact analysis manager.

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