September 21, 2011 - 12:00am

IP and Gigabit Ethernet networks provide a flexible, scalable, and cost-effective way to transport video, audio, voice and data. Because of these advantages, the use of IP based infrastructures to move compressed video within and between broadcast facilities is gaining popularity with professional broadcasters and content providers.

The adoption of IP technology is not without its challenges – as with any new technology, one must learn a dictionary’s worth of new technical terms in order to effectively install and configure IP video equipment.

In the rest of this blog, we will discuss some of the common terms and configuration parameters encountered when setting up an MPEG/IP delivery network.

A (multi)cast of thousands…

Unicast – A method of transmitting MPEG/IP packets from a single source device to a single receive device.  A separate unicast stream must be created from the source to every unique receiving device – even if the stream content to each device is identical.  The destination IP address and port values must be configured correctly on the source and receiving devices in order for the unicast stream to be received correctly. Unicast IP addresses must fall in the range of 0.0.0.0 to 223.255.255.255, but must avoid reserved address values for the network protocol in use (IPV4, IPV6, etc).

Multicast – A method of transmitting packets from a single source device to multiple receiving devices on the network using the concept of “multicast groups”.  In order to create multicast groups on an IP network, the network routers must be capable of supporting the Multicast IP protocol.  Multicasting allows multiple devices to receive or subscribe to the same MPEG/IP source stream while conserving network bandwidth by not requiring redundant packet transmissions from the source to each receive device.  Multicast group IP addresses must fall in the range of 224.0.0.0 to 239.255.255.255.

IGMP – Internet Group Management Protocol (IGMP) is an IP network communications standard used to establish multicast group memberships. IGMP is an integral part of the Multicast IP Standard. Newer versions of the IGMP standard have added enhanced multicast capabilities – version 3 (IGMPv3) added the ability to set up source filters to allow users to reduce traffic even further when many multicasts are co-existing on the same network.

Destination Port – The UDP port number where the receiving device looks for the incoming MPEG/IP data packets.  It is crucial to have this parameter setup properly on the receiving equipment; otherwise the equipment will not receive the stream at all.  It is a best practice to configure the transmitting equipment (encoder, multiplexer, etc) on even number ports, starting above port 3100 and keeping at least 6 ports between streams.

Source Port – The UDP port number from which the source device is transmitting MPEG/IP data packets.

Destination IP – Refers to the IP address where packets are being sent.  This can be the IP address of the receiving device in a unicast transmission or the IP address of the multicast group in a multicast transmission.

Multicast IP – Another name for destination IP, Multicast IP refers to the address of the multicast group where to which the source device is sending packets and from which the receiving device has subscribed to receive packets.

Source IP – the IP address of the sending equipment. Generally this IP address is only needed in IGMPv3 environments, when configuring an IGMP filter list.

IP Filter List – An optional list of IP addresses configured on a multicast receive device.  The list is used during the “join” process to tell the IGMP router which multicast sources to include or exclude when forwarding packets to the receiving device.  Configuring IGMP source filters can be used to limit network traffic to the receive device.

An important thing to keep in mind, IP was originally designed for the communication of sporadic bursts of data.  Successful delivery of compressed digital video data requires that the video packets arrive in a continuous stream. The video data must arrive on time andin sequence in order to be correctly and cleanly decoded and displayed to the end viewer.  Timing accuracy is critical in MPEG/ IP networks.  In future blogs we will cover what key signal parameters should be monitored and the importance they play in delivering quality video over IP.

Sencore is happy to discuss any questions you may have in setting up your video IP network or possible equipment solutions that will best fit your system needs and requirements. Contact us today. W.jones@sencore.com

IP and Gigabit Ethernet networks provide a flexible, scalable, and cost-effective way to transport video, audio, voice and data. Because of these advantages, the use of IP based infrastructures to move compressed video within and between broadcast facilities is gaining popularity with professional broadcasters and content providers.

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