Issue link: https://www.e-digitaleditions.com/i/1472963
July/August/September 2022 I 9 ICT designers and installers, who have not encountered AV over IP yet, will likely be seeing it coming to enterprise networks soon. A CLOSER LOOK AT AV OVER IP Audiovisual over IP is rapidly gaining acceptance as a versatile, scalable, secure, and cost-effective technology for distributing and switching video, audio, and control signals in AV systems, especially those with many end- points. ICT designers and installers who have not encountered AV over IP yet will likely be seeing it soon. Furthermore, AV over IP is sometimes abbreviated as AVoIP. It is a method of transporting digital audio and video over standard network switching and routing equipment for signal extension, distribution, and matrix switching. The digital audio and video are broken into segments and encapsulated in standard internet protocol (IP) packet headers. The IP data packets are carried from a transmitter to a receiver over standard networking equipment across a local network or over the internet. Typically, the AV over IP packets can also exchange additional data, such as USB, RS-232, IR, and other control signals associated with AV systems. Encoders and decoders at the endpoints compress and decompress the audio, video, and data to improve network efficiency. The encoder/decoder (codec) software algorithms that perform the compression are optimized for low-latency transmission of high-quality video and audio at low bit rates over 1 Gb/s or 10 Gb/s Ethernet network infrastruc- tures. The infrastructures can be dedicated AV networks or enterprise data networks that share bandwidth with the AV over IP packets. Current state-of-the-art AV over IP systems support video resolutions up to 4K@60 Hz. They also transport analog audio, embedded digital HDMI audio, and audio over IP, according to the Audio Engineering Society's AES67 standard for audio applica- tions of networks, thereby allowing integration with audio digital signal processors (DSPs) or other IP-enabled audio components. When deploying AV over IP, it is important to be familiar with the following network management protocols that are key to efficient transmission of AV over IP data packets: Multicast Multicast is a "one-to-many" form of group com- munication where a single data stream is addressed to a group of destinations simultaneously. It is consider- ably more efficient because it significantly reduces the bandwidth required over unicast, a "many-to-many" form of group communication where a separate stream is sent to each endpoint. Internet Group Management Protocol (IGMP) The IGMP is active on the network layer of the open systems interconnection (OSI) protocol. It is used to establish membership in a multicast group. Furthermore, IGMP manages multicast group memberships by marking packets in messages sent between a router and the hosts. Each sending host applies a unique identifier to multicast packets so that they can be located, then separated or forwarded as required. IGMP Snooping Most network switches are Layer 2 devices operating on the link layer of the OSI protocol. Since Layer 2 devices are typically unaware of IP addresses and the IGMP protocol, they cannot filter multicast packets. With IGMP snooping, Layer 2 devices, such as a switch, can listen to IGMP queries and configure Layer 2 LAN ports to selectively forward multicast traffic to only the ports that should receive it.