In 2014, ESPN opened Digital Center 2 (DC2) in Bristol, CT. DC2 is a $125 million, 190,000-square foot broadcast facility. The infrastructure can handle 60,000 simultaneous signals and 46 Tbps throughput. It stood as one of the first large-scale implementations of an AVB technologies-based solution, using:
- Evertz fiber-optic routers
- Arista switches
- comms provided by Riedel
- 1,100 miles of fiber optic cable
This article continues a three-part series exploring AVB/TSN’s role and impact at ESPN. Read Part 1: Why Ethernet Audio Video Bridging? and Part 2: AVB/TSN for Audio Video Production
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The Continuing Benefits of AVB/TSN
When ESPN designed their new digital center, they chose Audio Video Bridging / Time Sensitive Networking (AVB/TSN) — the IEEE set of standards that uses bandwidth reservation protocols and synchronization to ensure delivery of time-sensitive data. While the project required a massive feat of engineering and significant costs, ESPN found long-term benefits from the reliability, flexibility, determinism, power, and simplicity of AVB/TSN.
Cost-Reduction
With AVB technologies, the dedicated channels over standard Ethernet cables would mitigate the need for dedicated cables for audio and video signals. This allows for significant cost reduction, both in the cable, and in the installation and maintenance of it:
- In their previous facility, dead cables stayed in place, impossible to find and fix in a rat’s nest. As a result, 30% of cables were unusable.
- Without extensive cabling, raised flooring would become less necessary in future buildings, resulting in an estimated reduction of $3 million in construction costs.
- Ease in expand-ability to eventually support the whole campus at 4K definition video. Consequently, this limited costs in upgrading.
- Easy trunking to remote facilities meant substantial cost benefit for refreshing current facilities.
Software-Defined Network
Another significant benefit came from the nature of a network that stays “aware” via monitoring and filtering. Specifically, their Broadcast Audio Monitoring (BAM) service could listen to 32 streams on each panel. In addition, it could keep track of all the devices talking to the network. As a result, BAM could:
- monitor 16,000 streams at once to check status
- analyze the type of stream
- define who can connect to what
- reach out to connect if streams stop
The software would define the available streams for the hardware, while each node stays aware of the connections as defined by the software. This makes it easy to reestablish connections after any dropped signal.
AVDECC: A Layer of Intelligence
With rich diagnostic capabilities and supervision, each node communicates via the Audio Video Discovery, Enumeration, Connection management, and Control (AVDECC) protocol. AVDECC provides a format to manage, filter, and monitor every piece of data in the AVB network. Further, it helps deliver the right data to the right listeners.
The AVDECC protocol provides an expansive set of useful features. The list below shows only a few examples:
Device Discovery
- Periodic Advertising Existence (otherwise an indication of unexpected departure)
- Advertising Departure
Enumeration
Enumeration makes it possible to query information from an entity/endpoints.
- Endpoint Name, Manufacturer, etc.
- Endpoint Configuration (or the properties of the endpoint)
- Determination of the total inputs/outputs audio/video
- Description of flow of audio to mixers, jacks, etc. within the endpoint
- Input / Output stream names and properties
Connection Management
- Configuration / Management of the system connections (no dedicated connections)
- Fast Connect (unit intelligence to reconnect previous connection if any part of the system experiences an interruption such as a power failure)
Control Protocol
- System Configuration of each node / endpoint (to set up different formats, names, and properties)
- Notifications (allows controller to stay informed of changes detected in the system)
- Identification (allows users to locate endpoints)
- Field Upgradable (groups of endpoints all together)
- Forced rebooting from a central location
- Diagnostics (logging of events)
- Locking Entities (allowing exclusivity)
Pioneering AVB Technologies
By creating a network infrastructure with the low latency, time-critical benefits of Ethernet AVB/TSN, ESPN established their facility as a pioneer in the rapidly growing area of time sensitive networking. Additionally, as an open set of standards, AVB technologies offered ESPN the flexibility of interoperability with future equipment, lower costs, and the ability to design a custom system for their needs, ensuring easy expansion for their future broadcasting needs.
References:
Hayes, Michael. “ESPN DC2 Project Overview.” Audio Engineering Society Convention. Los Angeles Convention Center, Los Angeles, CA. October 2014. Powerpoint presentation.
Pannaman, Jonathan. “ESPN DC2 Design Philosophy.” October 2014. Powerpoint presentation.
Daley, Dan. (2014, June 10) “ESPN’S DC2 Scales AVB Large.” Retrieved from http://www.sportsvideo.org.
Photo attributed to JoeJohnson2 under the Creative Commons 2.0 Generic license.