IP Networking Guide for Video and Audio Applications

Transporting audio and video streams over IP networks creates requirements beyond the well-known settings for e.g. office networks. This guide outlines general aspects of networking as well as the specifics needed for the correct transport of real-time audio and video data over standard IP networks. Even though the guide uses Lawo IP devices as examples for specific settings, these are also applicable for equipment from other brands. The guide covers the following aspects:

  •  General requirements
  • Multicast
  •  PTP
  •  Quality of Service

Most of the audio and video streams in broadcast are transported using multicast (instead of unicast) in order to provide the data stream to multiple interested parties in the network without the need for the source to duplicate the data every time another destination requests the stream. For a correct, reliable and bandwidth conscious multicast operation some specific settings have to be configured.

As networks are slowly replacing dedicated video and audio connections, the reference for video and audio needs to be transported over IP as well. The Precision Time Protocol (PTP) provides a network-wide, accurate time which can provide a phase-accurate reference information for video and audio streams.

In a congested network, it is important to prioritize audio and video streams over e.g. FTP traffic in order to avoid audio and video signal failures. This prioritization can be achieved by employing Quality of Service (QoS).

The guide also outlines the resulting requirements for switches and provides some example configurations for switches that have been used in this type of application.


Topics:

 

IP Networking – General Overview

Bandwidth – Latency – Packet Delay Variation – Error rate – Additional factors – Physical Layer (Copper, Fiber, SFP Connectors)

Multicast

Overview – Querier Election – Multicast Router port – IGMP Report Flooding – Unregistered multicast flooding – IGMP Fast Leave – IGMP Performance –  “Half IGMP” mode

PTP

Overview – Profiles – PTP Timing Accuracy

Quality of Service

Overview – DiffServ

Ports and Communication Details

Ports – Commonly used multicast addresses – Communication details

Switches

Requirements (Bandwidth, QoS, Spanning tree, PTP, Multicast, Performance) – Settings – Limitations – Switch models

Leased data connections

Bandwidth and QoS – Latency and Packet Delay Variation – Measurement – Sample line characteristics (LAN, WAN) – Lawo device performance

Bandwidth examples 


Specific Switch Configurations

Cisco SG300 – Arista (PTP E2E) – Artel Video Systems ARG Quarra Switches

Troubleshooting

Multicast – PTP

FAQ


Glossary

 

Standards

 

 

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