Diverse Multicast Tree Design Overview

High quality video distribution (such as high-definition IP TV) with strict SLAs for packet loss and jitter are continuing to be rolled out by major broadcast service providers across the globe. Such a video distribution network requires that bandwidth be reserved along a fixed pre-allocated transmission path. There are currently two possible solutions for protecting such a path:

1. Use pre-configured FRR LSPs to protect each LSP branch. However, the drawback to this approach is that large spare capacity is needed for all the backup LSPs.

2. Use Diverse Multicast Trees. Here a separate multicast distribution tree is routed that is strictly diverse from the main tree in order to achieve 1+1 protection. For two multicast trees to be diverse from each other, the paths (i.e., the sub-LSPs of a P2MP multicast tree) to each destination from the source of each of the two trees have to not share any link or site or facility, depending on the diversity level.

Designing diverse multicast trees is a complex network design problem; in fact, it is NP hard (Non-deterministic Polynomial time hard) and not readily tractable for manual computation. A powerful and heuristics-based algorithm is needed to solve the problem for large networks. NorthStar Planner has a powerful Multicast Tree Design module that allows the user to design separate multicast trees that are strictly diverse from each other. The design solutions are as efficient as possible and can lead to large savings in capacity requirements for the network planner.

The following sections of this chapter describe the Multicast Tree Design features that are currently supported by NorthStar Planner.

Use these procedures if you have multicast trees (i.e., P2MP trees) configured in your network and if you would like to use NorthStar Planner to help you to design diverse multicast trees.

If you wish to perform these tasks in NorthStar Planner, you should have a network router specification file open before you begin. Otherwise, you should have a set of router configuration files ready to be imported into the tool. The chapter assumes the user is familiar with IP, MPLS, traffic engineering, P2MP, and IP multicast.