Video conferencing, digital signage and other A/V components are an increasingly critical part of the IT environment. These components must connect to the data network for content distribution and control. However, few organizations consider A/V when designing the network infrastructure, which creates bottlenecks and performance problems and limits an organization’s ability to support many A/V standards and protocols.
The traditional campus network model consists of three layers. The core layer provides high-performance switching as well as connectivity between sites. The distribution layer uses routing and Layer 3 switching to move data between subnets and VLANs. The access layer provides connectivity for endpoint devices. The network will also include a firewall and other security controls, and a wireless LAN controller for Wi-Fi access.
The cabling plant is the physical backbone that connects these layers and handles the flow of data. Users connect via an Ethernet port or through Wi-Fi. This physical layer is where many fundamental A/V connectivity problems occur. Conference rooms simply don’t have enough ports to support IP-enabled phones, displays, sound systems, screen-casting devices and control systems. A conference room may be allocated just one IP address, when in fact it will need many more. A/V may share the same VLAN with other applications.
Assuming that all of the A/V components are able to connect, network performance problems can result in a poor user experience. Common symptoms include garbled voice calls, jerky video conferences and even dropped connections. The network lacks the Quality of Service capabilities needed to minimize jitter, latency, packet loss and other issues that impact the delivery of real-time, interactive applications. These issues may appear regularly, intermittently or only in certain locations.
Insufficient bandwidth is another major problem. Video consumes a lot of bandwidth, and organizations with multiple conference rooms will have a lot of video data flowing across the network at any given time. Without adequate bandwidth, A/V systems will be unable to transmit or receive content. In a worst-case scenario, the network could fail, especially when users are experiencing significant packet drops.
Bandwidth issues also arise with real-time versus delayed streaming. If a user is watching a YouTube video, it’s OK if the video buffers. But if a company is streaming a presentation by the CEO for an all-hands meeting, it is critical that the video not be delayed. The network pipes must be big enough to ensure a high-quality viewing experience.
Furthermore, it’s important to remember that TCP/IP networks operate on a “best effort” model. There’s nothing inherent in the network to prevent an application from hogging the bandwidth. There must be some mediation between applications and policy-based mechanisms for managing traffic. It’s also important to use the right video codec. The JPEG2000 video codec is used for real-time streaming, whereas the H.264/H.265 codecs are used for delayed streaming.
This is just a high-level look at some of the networking issues that can impact A/V systems. In future posts we’ll discuss the network hardware requirements for various A/V standards and protocols, several A/V use cases, and Rahi Systems approach to A/V network design. In the meantime, we invite you to contact the Rahi Systems networking and A/V teams to discuss your specific needs and challenges.