Monday, July 29, 2013

Asymmetric Bandwidth is Hot for Business

By: John Shepler

What has characterized serious bandwidth for business applications has been symmetry, or having the same Mbps capacity in both the up (transmit) and down (receive) directions. That’s being challenged, now, by new service products that promote asymmetry. Asymmetry means having a different bandwidth available depending on whether you are uploading or downloading. Let’s have a look at why this is happening and if it can be advantageous for your business.

Asymmetrical vs Symmetrical bandwidth services? How to choose...Symmetry has its roots in telecom services that go back to the development of digital line transmission a half-century ago. The inventor of the T-Carrier standards, including the ubiquitous T1 line, was Bell Labs. Bell’s mission was to serve the telephone companies, so the digitization of telephone calls preceded computer to computer communications by decades. Switching from analog to digital long lines virtually eliminated the noise, distortion and crosstalk effects that plagued domestic long distance and international phone calls. It also enabled systems that could transmit hundreds and thousands of simultaneous phone calls on a single circuit.

Why symmetrical operation? Phone calls are bi-directional in nature. It doesn’t matter which end of the call you are on. You need the same line characteristics so that you can talk and listen simultaneously. This results in transmit and receive paths that are identical in design.

When T1 lines, DS3 connections and fiber optic circuits were pressed into service to meet the demand for computer communications, they automatically came with symmetrical bandwidth as well as dedicated circuits, synchronized channels and low latency and jitter. These features of Time Division Multiplexing (TDM) get the job done, but at a price.

Asymmetry has its roots in the rise of the Internet and consumer based Internet Service Providers (ISPs). When you access a web site, you send a small burst of packets to tell the server what you want and get back a large burst of packets that carry text, images, audio and video. Nearly all web access by users requires a lot more bandwidth in the download direction than in the upload direction.

This works well for telephone companies providing DSL over shared phone lines and cable companies using spare channels to deliver broadband Internet. Cable, especially, is a one-way medium. When TV was the only service, all channel content went from the head end to the consumer. For asymmetrical broadband, many fewer channels have to be allocated for the upload direction. That leaves the rest available for higher download speeds at premium pricing.

What some businesses, especially the smaller ones, have found is that asymmetrical DSL, cable, wireless and satellite broadband meet their needs just fine. This is especially true when their employees use the Internet primarily for web access and occasional email. Cable broadband is readily available and gives you higher download speeds for a fraction of the cost of a T1 line. When you get into higher bandwidths, say 10 to 100 Mbps, the cost differences are like night and day.

There are some hitches in this rosy scenario. Asymmetry is only one reason why DSL and Cable are cheaper than T1, DS3, Ethernet over Copper and fiber. A big driver in this cost reduction is shared rather than dedicated bandwidth. With shared bandwidth, the Mbps you have in either direction varies constantly depending on what your neighbors are doing. It’s one big bandwidth pool and the more users who are swimming in it, the less bandwidth is available to each user. This can get annoying when you have a critical project in the works and you can’t get much done because other people are downloading high definition videos.

Another difference between the symmetrical and asymmetrical services is that the symmetrical ones tend to be tariffed telecom services with Service Level Agreements (SLAs) that specify repair times for circuit outages, usually in a matter of a few hours. The consumer oriented asymmetrical services tend to be classified as “data services” and are provided on a best effort basis. The carrier will take your complaints seriously, but they may not be able to get the line fixed for some time.

Asymmetry doesn’t work for everyone. Applications like disaster backup and recovery, video conferencing, PBX & enterprise VoIP telephony, cloud computing and large file transfers between multiple business sites really need line symmetry for optimum performance. Companies running these applications also tend to need dedicated bandwidth and service level agreements to ensure maximum productivity.

Even so, the heavy competition from cable and other service providers is causing some major telecom carriers to rethink their service offerings. MegaPath, for instance, is rolling out asymmetrical service to customers at a cost savings. They are still differentiating their service with dedicated bandwidth, SLAs and Quality of Service (QoS) options for business applications that need these characteristics. Other big telecom carriers are expected to follow suit.

With so many service providers and connectivity options, how do you choose the optimum service that gives you the performance you need for the least expense? The best way is to get help from a bandwidth broker who works with many service providers and has the volume to get you the best discounts. Get instant online pricing and available consulting for bandwidth services available for your business locations.

Click to check pricing and features or get support from a Telarus product specialist.

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