Broadcast companies must design the network using a true central-derived model and control the elements within it using SDN routing. It is the most effective way to take advantage of the full potential of IP technology
By Olivier Suard *
Given the increasingly competitive nature of content transmission, any new technology that can improve productivity and allow cost savings will be more than welcome. The increasingly high adoption of IP technology is, therefore, no surprise. Considered less expensive in the long term than the specific baseband technology for content transmission, the IP protocol can also make use of existing technology and infrastructure. For many, this represents a huge advantage, since it eliminates the need to make major modifications.
So far everything seems fine, except for the fact that this approach can significantly limit the great potential of IP technology. Unfortunately, encouraged by some IP switch providers, operators sometimes fall into the trap of focusing on the products. The primary focus must be on obtaining the appropriate network architecture and control for the applications and workflows of the content transmission.
Currently, three architecture configurations are used in the transmission of content and in other industries.
Centralized star network
This approach is consistent with the conventional baseband architecture: all connections go through a large IP router that is in the main control room. However, this implies that there is no signal aggregation at the edge of the network: everything must travel to the central router. Fibers must be placed to connect each device to the central router.
To meet the increased demand and anticipate future needs, content transmission companies often acquire a large router from the beginning. The capacity limit is often reached sooner than expected, at which time it is necessary to replace the central router.
In addition, each connected device occupies an expensive high-bandwidth port in the central router, regardless of the actual bandwidth requirement. This raises the cost per port of low bandwidth devices. The lack of aggregation implies that redundancy must be handled by network edge devices.
Finally, a star network architecture, by its nature, is not ideal for remote locations as extensions of the primary location, since it implies that all traffic must pass through the central router.
Initially, star networks may seem simple and convenient, but in practice they are very limiting, potentially vulnerable and very expensive.
Large data centers often adopt a distributed IP network model, known as a central-derived architecture (spine-leaf). This involves the use of two or more routers in the core (central) and other smaller routers in the edge (derivatives).
By connecting all the equipment in each area to derived aggregation routers, and then connecting these to the main routers, the companies reduce the number of connections that go directly to the main routers, which simplifies fiber management. If there are fewer fibers, fewer ports are also needed in the central router (s), and a lower cost per port is achieved, especially for devices with low bandwidth.
The central-derived architecture facilitates redundancy in the network of all devices at a much lower cost. This model also offers optimal flexibility and scalability. The capacity can be increased by adding derivative routers (leaf) or central (spine), instead of replacing the existing en bloc, as happens in star networks. Thanks to this, the networks do not need to have a larger size from the beginning, since the capacity can be extended over time.
Although the configuration of a true central-derived architecture can be more complex than others, it is a scalable, robust and high-performance network structure that perfectly fits the needs of the transmission companies.
This third architecture model is what some might call a spine-leaf, but in reality, it is a "double star" architecture model. Although it requires the use of two central routers, each router derived from the network is only connected to one of the central routers.
This solution is not flexible in terms of load distribution and optimization of the total capacity of the network. As the network evolves, it imposes special requirements on terminal devices that need redundant connections.
Advocates of this architecture often prefer automatic routing based on protocols instead of SDN routing (software defined networks). Although a pseudo central-derived network could initially be more attractive due to the simplicity of its configuration, only a true central-derived architecture allows companies to get the most out of their investment in IP infrastructure in their facilities.
In addition to the network architecture, operators also need to organize and control the IP media network:
The protocols that conventional IP switches perform (for example, IGMP / PIM) allow network elements to make decisions about routing based on IP traffic. This means that the decision how to transport individual media streams through the network can be left to the network, not to the operator.
Although it is widely used in IP networks, automatic routing has disadvantages when it comes to professional networks of media production in real time.
For example, automatic routing may not be fast enough to transmit the large number of simultaneous switching events required in live production. You may also have problems with networks where there are loops and where bandwidth management may be poor.
Most of these problems can be solved by experts in IP networks, but it will be necessary to have their assistance whenever there is a significant change in the configuration, for example, if new studies are added or a large number of cameras are moved from one to another. place to another.
Network routing defined by software
Routing of software defined networks (SDN) leaves the routing control in charge of a centralized control level. The management and orchestration software has a complete view of the available equipment, the network infrastructure and the services, both those that the organization currently has, as well as those that are programmed. Thanks to this, you can make intelligent decisions efficiently on routing and flow control. It can also offer the explicit routing feature that content streaming companies expect and need.
SDN routing also guarantees a higher level of performance compared to automatic routing. The software also has control over all media streams, which means it has more information and is in a better position to deal with the current bandwidth requirements and even with the requirements that are programmed. It is even beneficial in terms of protection and security. Orchestration and control software can easily create a variety of ways to protect against failures, and can also fully control which destination a multicast can carry from a particular source, thus reducing security risks.
Unlike automatic routing, SDN routing can, with the appropriate orchestration and control software, easily process any network architecture without risk.
The content transmission companies must design the network using a true core-derived model (spine-leaf) and control the elements within it using the SDN routing. It is the most effective way to take advantage of the full potential of IP technology and at the same time helps to obtain an optimal return on investment and gives greater possibilities of operational success.
* Olivier Suard is the vice president of marketing for Nevion.