Distributed routing networks: Moving past a star infrastructure can increase benefits

Today’s modular routers with optical extensions are fully capable of switching, bringing with them the benefits of the latest technology. There are, however, inherent issues and challenges with traditional star-routing networks with point-to-point passive links. In addition to cost, a change in network configuration, such as the addition of a location in the network, requires significant infrastructure changes and costs, not to mention extreme risk to live video should network downtime result from patching errors.

A distributed routing network based on a compact router construction with an optical extension delivers a more flexible, scalable and fully redundant optical network. Through the addition of a distributed routing layer, it is possible to create a hybrid electrical/optical routing system capable of sending signals long distances while utilizing electrical connections for most of the local distribution. The result is a price competitive and more efficient system.

Past the star

Classic star architecture is not scalable once it reaches the limits of the main router. Additionally, it represents the “brute force” method of distributing signals to all locations. This method was cost efficient when cabling was done through coax cables. With the increased demand for high resolution content requiring high bit-rates, however, the distances coaxial cable could cover decreased, and optical links were required. In a traditional, point-to-point routing system, generally only 20 percent to 30 percent of the primary router is utilized for switching. This leaves 70 percent to 80 percent for distribution and takes the form of an expensive patch panel. An illustration of this is the amount of crew sitting in different locations during a production, watching the main program feed. This feed alone would normally be distributed to five or more places from the central router. And, with the high bit rates of these signals, distribution will be optical. This inefficiency of the router can be utilized when designing a new network.

An intelligent network management application enables broadcasters to take advantage of smaller, compact routers to move from a classic star network with a large primary main router to a distributed, redundant network comprised of smaller, interconnected nodes. Bringing the right management system to the table also enables an efficient workflow. Tie lines bind the distributed routers together, controlled by a management system that automatically finds the most direct and cost-efficient paths through the network. Redundancy is achieved not only from the router but also its configuration.

If a broadcaster wants to add a fourth studio to its current configuration of studios connected to a master control room, it may find that the primary router lacks the number of necessary ports for that expansion. Reconfiguring the main router entails large amounts of re-cabling and numerous patches to avoid network downtime, while limiting the ability to re-use the existing router.

The new approach and resulting configuration is based on identifying the distributed signal (or signals) that must be universally accessed. Consider a live TV setting with its need for different professionals to access the same feed. Let’s say an audio bay, lighting crew and makeup staff are located in different areas. All receive a copy of the same unique, main feed. When distribution is based on a central router, this transport is likely done optically due to distances. In a distributed routing setting, the signal is transported optically from the local distribution router close to the studio, and distributed from there electrically to the three sites. This also frees up cross points and ports to the main router.

A mesh or distributed network continually transmits signals and offers the most significant benefit: the ability to scale. A broadcaster can expand rather than alter its network, adding or replacing a node rather than a router.

This network design also allows distribution of commonly routed signals within the sites, local-to-local connectivity, and improved or maintained redundancy levels. Adding another location to the system does not compromise the network or require complex infrastructure changes. With a hybrid optical fiber network of this type, the broadcaster achieves a redundant system that offers security and scalability at an attractive price.