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Why software-defined networks are so darn nifty!

Software-defined networking (SDN) has been around for over two decades. Its use in broadcast is still fairly new, writes Lawo's Christian Scheck

The biggest advantage of a broadcast IP network is that all processing and ingest resources are, at least in theory, available to any operator. Control systems like VSM allow programmers to limit the number of streams a given operator can access. There are two good reasons for doing so: to avoid confusion and delays caused by an overwhelming number of sources and destinations only a few of which are relevant for the task at hand, and to ensure that unauthorised operators cannot access streams they should not touch.

Feeling insecure

A broadcast IP network is first and foremost a network, which means that once you are inside, you can potentially go anywhere. In light of disturbing news about hospitals, pipelines, and other entities that are suddenly out of control due to malicious interference, broadcasters are naturally concerned about the security of their content and the integrity of their channels.

The HOME management platform is in the process of tackling this issue based on user authentication and targeted security routines. Powerful though it is for a wealth of applications, HOME can only provide security on its own turf, that is, in the network sections that are directly managed by HOME.

This explains why some broadcasters that migrated to IP over the last few years decided to separate production from master control in a traditional way: by connecting these two departments to each other via baseband SDI cables. Since the connection between these two is not network-based, intruders simply cannot get from production to playout (the master control room).

Yet, any changes that may be necessary require physical cable (re)patching, which is time-consuming and error-prone.

If you migrated to IP for unalienated flexibility and agility, the SDI bridge is probably only acceptable while there is no other solution.

Stronger stuff

CBC/Radio-Canada just completed the largest IP-based infrastructure to date, a truly remarkable achievement. They did quite a few things differently: they decided not to hire a systems integrator, and they played an active part in architecting the network of their green-field Nouvelle Maison de Radio-Canada. 

This obviously put some pressure on the team to come to grips with the ins and outs of IP and other technological aspects, but this allowed them to tailor the infrastructure to their exacting needs.

There was some help from carefully selected partners that happily refined and extended the specifications of their hard- and software offering and shared their experience with the team. The biggest chunk was done in-house, however.

As the project progressed, the idea was voiced to rely on SDN technology to solve two fundamental problems, the first one being the ability to hide all signals from outsiders, and the second to achieve dynamic load balancing between the spine and leaf switches. SDN allows the team to work with two separate islands—with separate broadcast controllers—and to police the network, so that if a given stream is defined as HD but eventually transmitted in UHD, this does not bring down the network.

Of course, there are 100Gbps IP tielines between the two “islands” to allow produced content to flow to the playout department, and monitoring signals to return to the relevant master control rooms.

It is safe to say that CBC/Radio-Canada played an important part in the adoption of SDN in the broadcast world.

What is SDN?

Software-defined networking (SDN) is a network management technology that enables efficient, dynamic network configuration to improve performance and monitoring. With SDN, an enterprise has the ability to implement a new network with hardly any impact on the existing Infrastructure.

Inherently, an SDN controller in a central location does away with the limitations of a static network architecture by centralising all network intelligence in one place. 

The transportation aspect of network packets, on the data plane, is dissociated from the routing process, called the control plane. The controllers—because there can be more than one—act as the brain of the SDN network.

Operators are able to programme network control as the underlying infrastructure is abstracted from applications and network services.

All in all

IP technology is still evolving, not least thanks to bold forays into uncharted territory by a team of Canadian engineers who are now considered to be among the happy few who truly master the potential of their broadcast IP infrastructure. This, by the way, is not just because of their clever use of SDN technology.