Hitless-Protection-SwitchingHitless protection switch technology has a long history of successful applications, including a number of high-profile international sporting events fed to billions of live viewers around the globe. One major broadcaster said “Hitless technology allowed us to deliver streams from South America to North America without losing a single packet during live video transmission for the full duration of our multi-day event coverage.” Another senior broadcast executive has indicated that hitless switching is a key enabling technology for reliable local and long-haul signal transmission as the company deploys hybrid IP/video networks today and migrates to all-IP based studio systems in the future.

The traditional application for hitless protection switching is to support long haul contribution links. This was the area where the technique was first applied, and formed a lot of the
background when the specifications were originally developed. Long-haul links typically include several network segments and can cross multiple carrier boundaries, so protecting signals
against both short and long duration outages is a valuable capability.

As RTP-based protocols take over interconnection duties within IP studios, hitless protection switching can make sense within the walls of a production studio. Ethernet links are designed to meet a worst-case BER of 10e-12, which means that an error can occur once every 100 seconds on a 10 Gbps link and still remain within spec. A single bit error on an Ethernet link will cause an entire packet of IP traffic to be dropped; this in turn would mean that the data for several hundred pixels would be lost. Hitless protection switching would easily be able to handle these errors, and might not require adding equipment in a production facility that was constructed to provide 1:1 redundancy.

More broadcasters are using terrestrial fiber-optic connections in place of satellite links to distribute their content to major partners, such as multichannel distributors (MVPDs) and OTT program delivery systems. This trend has been driven by consolidation of MVPD head-ends into fewer, national centers; by the push for higher signal quality through fewer compression steps; and by the greater reliability offered by fiber-based systems. OTT service providers are critically dependent on highly reliable content feeds into origin servers – any content that does not make it into an origin server will not be available to OTT viewers. Hitless protection switching can be used to improve system reliability and signal availability for the critical first link to both MVPD and OTT providers. At these levels, even momentary outages can affect millions of viewers simultaneously, so ensuring system dependability is a good practice.

Multiple equipment and service providers have demonstrated interoperability between devices that support SMPTE ST 2022-7. As the only available technology that can withstand partial network outages lasting multiple seconds, coupled with the flexibility to support uncompressed UHD video and 10 Gbps data flows, hitless protection switching has a “can’t-miss” future in high reliability networking. 

To learn more about SMPTE ST 2022-7 Seamless Protection Switching download our white paper, Broadcasters Can't Miss with Hitless Technology

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