Planning for 3Gb/s routers AND BEYOND
Mar 1, 2007 12:00 PM, BY TODD RIGGS
Getting in control
With large routers, there are many choices to make. Large routing systems often offer different types of control panels that can be located throughout the facility, depending upon the unique requirements of each work area. Router control panels can be X-Y, multi bus, single bus or button per source in function, and hardware, software or Web-based in type. Prices are going to vary depending upon size, type and quantity of the control panels that are chosen, and that's something the broadcaster and systems integrator will have to consider.
With a Web-based interface, control, configuration and diagnostics can be accessed from PCs that can log into a facility's LAN or WAN, thus making it easier to control routers that are on site locally as well as remotely.
Also, different areas of the facility have control requirements that call for different types of panels. They may also vary as to the accessibility of numbers of sources and destinations. Thought needs to be put in to analyze job function to determine the type of panel required, as well as user and group access rights and privileges.
Because control panels are not typically on a large router's frame itself, it must use a communications protocol to talk to the central router. Today, these connections can be made via serial port or coax, Ethernet and connection via the Web.
Control questions
The selection of control panels is an area that requires careful consideration. Among the issues that a prospective buyer must consider:
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How do different user groups need to view the sources and destinations on the router?
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How often do their particular list of sources and destinations change?
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What is their work location in relation to the frame's location?
There is a wide range of panels to choose from, and they vary by physical size, layout, menu structure, method of communications and price. There is no one-size-fits-all, and facilities will almost always have a combination of them. A designer needs to interview the various user groups to determine what their needs are so he or she can select the right panel for that job function. This is an important point. This is the user interface to the router. The system may run great, but a clunky interface will leave the engineering staff having to defend its decision.
Planning for growth
Planning for growth means anticipating changes and planning for how those changes will be handled. Questions to ask before buying:
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What are my control requirements?
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How is the router configured, and how easy is it to change?
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If you need to make changes, such as modify a database or add any I/Os, how does the system incorporate those changes?
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Can these modifications be done in the background, with little or no disruption, or do they require having the system to go down for a period of time?
The user needs to pick a frame size that will handle their current needs as well as future requirements. If a customer needs a 128 × 128 HD router with no expansion, that could most likely be put in a fairly small frame, say 10RU or smaller. If, however, the customer needs to expand, by how much does he or she need to expand? Is it just that particular format, or will the customer be adding additional formats over the life of the router?
Also, you don't have to buy a completely full frame right off the bat. Different manufacturers have different I/O granularity. Consider the cost to upgrade. A smaller I/O size potentially means it will be cheaper per board, which in today's world means adding a board or two for a few inputs doesn't have to go through the capital process.
The bottom line
Five years ago, many installations involved a separate video and audio router, but with advances in technology, it now makes sense to combine video and audio routing in the same system. For a television broadcast facility, a smaller router is beneficial because it leaves space for other things. But on today's space-challenged mobile production units used for HDTV telecasts of sports and entertainment, space is a critical concern.
A few years ago, many 256 × 256 SDI routers with AES audio would have required multiple frames for each format, all with their own power supplies, fans and controllers. Today, comparable functionality is available in a single frame that is 30RU or smaller.
This progress is owing to advances in the internal circuitry on the components; improved I/O layouts; improvements in power consumption and cooling; and smaller, faster processing components. This drastically reduces the physical size of the cards.
This consolidation has, in turn, reduced the footprint of the router itself, as well as the number of power supplies that must be used. The drastically reduced power consumption and cooling requirements lower the cost of operation, as well as extend the life of the system components.
For owners of older routers, the savings on the electricity bill and the cost of replacing bad power supplies can be significant over many years of operation. And that is money that could be applied towards the purchase of a newer, more energy-efficient router.
A house router has to work. So we need to ask:
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How reliable is it?
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Are the critical parts hot swappable?
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How easy is it to get to those parts if there is a failure?
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What is the power draw of the frame, and how does it cool?
That may sound trivial, but electricity bills come every month. It's part of the cost of ownership. A router that draws less power will cost less over its lifetime, while one that cools well will not require as much air conditioning. And those factors, combined in an efficient system, will allow for a longer life span of the individual components in the frame.
Final key points
In a cost analysis of a major router purchase, consider that internal converters will piggy-back on the router's existing cable and power supplies, whereas external routers will require additional cabling and power. Because of the complexities involved with the purchase, design and installation of a large central router, as well as the relatively lean engineering staffs at most facilities, many broadcasters and mobile truck companies must enlist the help of systems integrators.
However, once the system has been installed, broadcasters must plan for repairs, configuration changes and upgrades because these will be inevitable. Therefore, choose a router that provides as much easy accessibility from the front of the router, so you don't have to move equipment or pull it forward to access it from a rear panel.
Fans, control panels, power supplies and other key components all need to be hot-swappable parts. And there should be back-up components ready to take over should the main units fail. After all, fail-safe operation is the broadcasters' primary goal.
Todd Riggs is product marketing manager for Harris Broadcast Communications, Router Systems Division.
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