Multicasting video over a LAN

How you set up your network for voice, data, video, and audio transmission can mean the difference between a network that operates efficiently and transparently to users and one that’s slow and tedious.

Think of your network as a river of data. You have a steady current of data moving smoothly down the channel. All your network users are like tiny tributaries branching off the main river taking only as much water (bandwidth) as they need to process data. When you start to multicast voice, video, data, and audio over the LAN, those streams suddenly become the size of the main river. The result is that each user is basically flooded with data and it becomes almost if not impossible to do any other tasks. This scenario of sending transmission to every user on the network is called broadcasting, and it slows the network down to a trickle. But there are network protocol methods that alleviate this problem.

Unicasting vs. multicasting
Unicasting is sending data point-to-point, from one network device to another. Multicasting is transmitting data from one network device to multiple users.

When multicasting with Layer 2 switches, all attached network devices receive the network packets, whether they want them or not. When you multicast with Layer 3 switches (with multicast support), you send the network packets to only the exact client/receives who want them. You control where the river of data goes and put up locks to keep the river out of other user streams.

Continue reading


Extending the life of your data center

Given the heat wave so much of the country is experiencing (deepest sympathy to those readers in Richmond, VA that may experience a heat index of 118 degrees today); we had an itch to talk about cooling. That is, cooling in the data center.

Did you know that legacy data centers waste at least 50% of the energy they consume managing heat generated by IT systems? Most data centers are not new; they are housed in buildings that are using practices that could be 20 years old and have not yet caught up with the latest trends.

Fully populated racks can dissipate as much as 7–25 kW of heat per rack. High-end servers can dissipate more than 40 kW per rack. This level of density requires data centers to provide power and cooling densities that exceed typical current capabilities.

Continue reading

The psychology of network (in)security

Is your company concerned about being connected to the Internet? If so, you’re not alone. It’s the fear of being successfully hacked that’s keeping many companies and their employees off the Internet. In fact, according to Infosecurity News, over 25% of all companies polled responded that hackers have tried to gain unauthorized access from outside the corporate network.

What else keeps companies disconnected? Hackers are no longer just techies with a hobby. Hackers are no often highly trained professionals in places like Eastern Europe, Russia, or China, and they’re out to make a profit on you. There’s a mystique to being hacked. It’s the new crime, it’s the hottest news.  And it’s fun…according to hacking group Lulz Security, whose motto claims they are, “The world’s leaders in high-quality entertainment at your expense.” Well they sure aren’t fun for you. If anything, this hype from the media watchers and technical experts, should be keeping you on your toes.

Continue reading

How to plan for your digital signage application

Before beginning any digital signage project, you will need to assess your site and your resources by:

Surveying the site where the digital screens will be placed.
Ensure that you can adequately mount, power, and have room to troubleshoot the installed LCD, plasma, or other screen. Be sure to have a technician verify the power levels for every location, so that it’s clear of line noise and consistent, and there’s enough airflow. Excessive heat can cause sensitive electronics to perform inadequately or even fail.

Also determine the lighting at all hours of the day. If it’s under fluorescent lighting or in areas with a lot of sunlight, you may need panels with suitable coatings, the kind that reduce the amount of reflective light. And along with the ambient light, determine how much ambient noise is present. You may have to use larger speakers, at different angles, for your site’s application.

Don’t forget to take into account the size of the audience you plan to reach. Plasma screens with wider viewing angles may serve you better than LCDs in certain spaces. Touchscreen displays are a technology on the rise as well. This allows you to set up more advanced, interactive signage. Surveying traffic flow patterns at different times of the day will also help you determine optimal screen placement.

Continue reading