During the last few years, there has been a continual increase in the use of IT-based equipment in the broadcast industry. More and more broadcast devices for storage, manipulation and transport are now actually computer file-based systems. The industry transformation to what is essentially a hybrid broadcast/IT infrastructure has presented some challenges. Most notable is the issue of how to realize real-time switching on an IT network that isn't necessarily real time.
In simple terms, the signal-specific routing equipment that has been used in the broadcast industry basically made a direct connection to a piece of equipment at point A with another piece of equipment at point B (and C to D, E to F, etc.) without any worry of interference from anything else going on in the system. Now, with the use of the computer file-based equipment and Ethernet networks for the transport of digital video, files are transferred between devices using normal IP file transfer techniques, and all devices share the same pipe. Because of the extremely large size of these files, the time required for file transfers can be long and can be affected by the presence of other data traffic that is present on the network. The challenge is: How do you get the guaranteed bandwidth on the network when you absolutely need it?
To solve the problem, Utah Scientific developed the UTAH-400 iP network switch, which allows for a managed Ethernet network with dynamic allocation of bandwidth, QoS and VLANs. The unit is designed to return real-time control of the switching fabric back to the broadcast engineer.
The problem with networks
An IP network is often viewed as an inflexible, unmanageable configuration that results in performance that is fixed and has to be “lived with” as it is. Of course, there are methods to control the behavior of the network, but periodic disruptions, such as one user on the network consuming a large amount of bandwidth that results in loss of or impaired use for other users, are considered normal occurrences.
Built into the hardware and software of industry standard IP switch products are various methods to control the behavior of the network. These are used in varying degrees in different installations to do things like provide for priority of certain types of data traffic (video or voice, for example), isolate critical network segments from noncritical ones, and limit available bandwidth for noncritical functions. These methods include the IP type of service (TOS) or DiffServ features to allocate traffic priority, VLAN segmentation to isolate network segments, and ingress/egress queue management to control bandwidth.
To date, these methods can be used at the system configuration level. In other words, once they are set up at the design and installation phase of the network, they are typically never altered, unless a portion of the network changes, and the video engineer in charge of day-to-day operation has little control of the system. To make changes, a system administrator would need to modify the setup parameters, and the system then continues on as before. It is a functional approach, but it is not dynamic. It relies on specialized IT personnel with extensive training to effect changes to the network. Some control parameters, such as IP TOS, can be made available, but they are not normally used because of the unwieldy nature of the management.
A new management method
The UTAH-400 iP network switch can control an IP network in real time, allowing for much more flexibility in the use of a new or existing IP network. Users do not have to live with limitations designed into their network. Traffic prioritization becomes something that users are allowed to control. Network segmentation can be changed for daily maintenance or backup functions on an automated or manual basis.
Perhaps most importantly, critical functions can be granted priority immediately, without intervention from an IT professional. And, the administrator can grant how much control each user has to assure integrity of the network.
With the network switch, network management can be implemented in a variety of forms, which have all been proven in real applications over the last 30 years. These range from industrial control panels to automation applications to inband, transfer-by-transfer controls.
Making IT networks work for broadcast
IP TOS identifiers that manage traffic priorities in a network have been in place since the inception of the TCP/IP protocol. These methods work well for prioritizing one type of traffic over another, but not at determining priority between two or more streams of the same type of traffic. So, for example, if two editing workstations are simultaneously trying to move video files to a server for play-out on the evening news, there is no way to distinguish between and give priority to the clip that has to go to air in 60 seconds and the one that's not needed until after the first commercial break.
The UTAH-400 iP allows users to prioritize traffic coming from any device to any one of eight tiers that they desire, in real time. This approach works well for situations where multiple data streams are competing for a given port's bandwidth. Even when a network is designed with a large backbone bandwidth, connections to individual devices or between network segments will have a finite bandwidth that can be overrun if it is not managed. With dynamic TOS management, the data stream with priority can be guaranteed to arrive at the destination port no matter what other devices on the network are attempting to do — so the clip that needs to go to air in 60 seconds is given network priority with a simple press of a button. And the priority can be changed at a moments notice based on user needs and the changing dynamic of the broadcast day, or remain in a predefined configuration. (See Figure 1.)
Another management method available on the typical IT network is the control of VLANs. These are logically separated paths within the same physical network infrastructure. They allow users to segment a part of their network away from other parts. Dynamic control of VLANs with the UTAH-400 iP can allow users to segregate a network however they wish, and to change this as different needs arise. This management method is essentially the same concept as a traditional broadcast XY router in application.
Bandwidth, the physical payload of any given network port, is typically represented as the speed of the interconnect, i.e., 10Mb/s, 100Mb/s or 1000Mb/s. While this accurately defines the maximum speed of the interconnect, the actual bandwidth can be modified by limiting the data capable of being passed over a specific port. Queues within the input and output sections of each Ethernet port on a switch can be dynamically bandwidth-limited at the discretion of a user. This allows a user to restrict data from a specific port that is involved in a noncritical activity, and then increase it to full bandwidth moments later when it is involved in a critical task. This brings another level of flexibility in the behavior of the network to the end user.
Conclusion
Monitoring and managing IT networks through the use of the UTAH-400 iP network switch brings a new flexibility to Ethernet networks that makes them much more functional and adaptable to the dynamic reality of the broadcast environment. The switch allows for time-critical reconfiguration of any preplanned network without compromising the functionality that users are used to now. The result is an environment where users can identify and correct bottlenecks before they cause problems.
Jeff Levie is CTO of Utah Scientific.
