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Success with IP requires insight into network architecture and control

Olivier Suard, Vice President of Marketing, Nevion
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The Holy Grail of increased productivity leads many broadcasters towards IP technology. Its attractions include lower costs than broadcast-specific baseband, and its ability to handle any video and audio technology.

Too often, however, broadcasters initially opt for a like-for-like network replacement, which denies them the cost-savings and increased flexibility of IP LAN/WAN convergence. Instead, broadcasters need an approach that accommodates the specific needs of their industry. For that reason, the initial focus should be on getting the network architecture and the control right.

Centralized star network

The tendency for most broadcasters is to adopt a ‘centralized star network’ with all connections transiting through a large IP router. Unfortunately, this architecture requires every single device to have an expensive fibre connection to the central router.

Scalability is difficult too, because capacity is often reached sooner than anticipated, necessitating replacement of the central router at high cost-per-port. Lack of aggregation also necessitates two connections to the central router, while the assumption that all traffic will transit through the central router makes star network architecture unsuitable for treating remote locations as extensions of the main location.


Another option is spine-leaf architecture involving two or more routers at the core (spine) and other smaller routers at the edge (leaf).

This reduces the number of connections, simplifies fibre management, requires fewer ports on the central router(s), and is more cost-effective, especially for low bandwidth devices. Spine-leaf architecture reduces the cost of redundancy and provides optimal flexibility and scalability. Since additional capacity can be added as required, networks do not need to be oversized at the outset.

While true spine-leaf architecture can be more complex than other approaches, it is a scalable, resilient and high-performance structure perfectly suited to the needs of broadcasters.

Dual star

A third model is ‘dual star’ architecture which uses two spine routers, but with the difference that each leaf in the network is only connected to one spine.

The drawback here is failure to optimise load distribution or total network capacity and frequent occurrence of redundancy problems. Only a true spine-leaf architecture enables broadcasters to get the most out of their IP infrastructure investment in their facilities.

Yet, as well as these thorny questions about architecture, broadcasters also need to orchestrate and control the IP media network, weighing up the comparative advantages of automatic routing and Software Defined Networking (SDN).

Automatic routing

Automatic routing means leaving the decision about how to transport individual media flows to the network, rather than the operator. Although this technology, and the IGMP and PIM protocols, are used widely in IP networks across the world, they have disadvantages in terms of performance and bandwidth management.

Automatic routing struggles with the pace of live production and has difficulty coping with network loops – problems that can only be fixed through higher operational complexity – and unless care is taken in designing and controlling the network, it will be hit by instability and signal drop-outs. On top of this, security remains a concern, as streams to destinations are not explicitly controlled.

Software Defined Network routing

SDN puts routing control in the hands of a centralised control layer. The management and orchestration software holds a complete view of the available equipment, the network infrastructure and the services. This enables it to make intelligent decisions about flow routing and control and provides the explicit routing capability that broadcasters need.

This guarantees a higher level of performance when compared with automatic routing, since the software is also in control of every media flow. It is also more secure. The orchestration and control software easily create path diversity to protect failures and offer added protection by fully controlling which destination receives which multicast.

Unlike automated routing, SDN can, with the right software, easily handle any network architecture. It certainly emerges as the control of choice for the creation of truly flexible, scalable and high-performance IP media networks.

While the benefits of IP technology are obvious, broadcasters should still bear in mind that a successful IP depends on the right infrastructure and on the way in which individual elements within the network are controlled.

Broadcasters should design their networks using a true spine-leaf model, and use SDN routing for control. This is the most effective way of maximizing IP technology to achieve operational success in real-world conditions and deliver optimal return on investment.

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