“When migrating to AV-over-IP, the control layer is one of the most crucial aspects to consider, as it affects nearly everybody who interacts with the system on a daily basis,” says Brad Price.
Brad Price is Senior Product Marketing Manager at Audinate.
As AV-over-IP increasingly becomes the de facto standard way of doing things in broadcast, the need to understand the entire “stack” that comprises any solution is key to making decisions that will serve your studio and your talent. We take a look at the various layers here.
The transport layer sets the rules by which traffic flows between devices over a network. It consists of several layers of widely used, reliable standards that implement data flow over compatible hardware, such as network switches. On top of this are specific transport definitions for different data types.
Standards like AES67, RTP, SMPTE-2110 and IEEE1588 are all part of this layer. It is here that clocking and packetising of audio and video occur, and media are sent to and from devices over a network. Access to transport is through the control layer, designed by manufacturers and separate from underlying standards.
It should be noted that these underlying standards all do a very good job when properly implemented.
Next comes the control layer, where implementation details and manufacturer differentiation start to appear. Standards alone don’t create the solutions we use; rather, they are roadmaps that inform designers about what is required to interact with others using the same standards. This gives manufacturers tremendous leeway in creating products that add value over and above the standards themselves.
The control layer is what most people think of when they consider an AV-over-IP solution. What does it look like? What metaphors are used to describe the system on a screen? How easy is it to change routes? How does one add devices? What happens when a device is renamed or replaced? What happens when the system is taken down and re-assembled? These are the key items that affect daily use, and none are dependent upon underlying standards.
When migrating to AV-over-IP, this layer is one of the most crucial aspects to consider, as it affects nearly everybody who interacts with the system on a daily basis.
Next up is the security layer, which must be implemented consistently across the entire system to avoid changes that create unintended or even catastrophic consequences.
As security must be system-wide, the implementation of security must reside centrally. In the IT world, that means a server that “sees” the entire system and can act upon any part of it. Network managers that provide insight into different domains provide this in the AV world. They are able to connect to all areas of an AV-over-IP network and restrict the use of the Control layer through enforcement of user authentication and role assignment.
A software management tool that allows for network and domain insight allows an administrator to assign real users different levels of access to different areas of the studio or system, from full control to view-only to nothing at all. It can be tied to any existing directory system used by IT (such as Microsoft Active Directory) so that users don’t have to be created “from scratch” and provides a simple and effective means of preventing unwanted changes in broadcast facilities.
The last one we are looking at is the administrative layer. Once a software network manager in place, this layer is used to configure zones of devices, clocking domains, and to extend the AV-over-IP system beyond LAN boundaries in larger systems. It provides monitoring of the entire system from a central location.
Domains are the equivalent of zones in legacy AV. They are groups of AV devices representing particular rooms or purposes, such as “Studio 3” or “Translators”. The security layer ensures users see only one domain at a time depending upon their level of access, thereby reducing visual clutter and likelihood of errors. Tie lines can be established between domains without the risk entailed from allowing full access.
The administrative layer “sees” all the domains and so can provide status information about each one – has a device been removed? Has someone broken the clocking arrangement for a domain? This layer offers a clear audit of all activity from devices and users alike.
Advanced network-wide functionality can be enabled at the administrative layer, such as support for clocking and AV transport across routed networks, overcoming the usual LAN limitations of unmanaged AV-over-IP.
An understanding of these layers helps us appreciate how the AV-over-IP package works within a broadcast facility.
