WebJunction

Updated by Carson Block & Rose Nelson on July 20, 2004

Confused by the dizzying array of options for your library’s connectivity? Maddened by the lack of options in your areas?  Feel lost in alphabet soup-like acronyms describing the technologies?  You’re not alone!

Below is a chart describing currently available connectivity options for dedicated circuits—that is, an Internet connection that is “on” all of the time. Some options listed below are not available in all areas of Colorado.

T-1:    A full T-1 Circuit has the capability of transferring data at a speed of 1.54 MB/second.  In the old days (before bandwidth-intensive things such as streaming video), a rule of thumb was that a single T-1 line could serve 100 users.

A “frame relay” T-1 is generally the most affordable version of the circuit.  By using the phone company’s frame relay “cloud” to combine the data traffic of many T-1 circuits that the phone company sells, it is able to offer the connectivity at a reduced price.  As well, some ISPs (Internet Service Providers) charge less for Internet services delivered via frame.   The down side is that the phone company will only guarantee half of the stated speed of the circuit at any given time.  For most libraries, this is an acceptable situation.

A T-1 circuit is symmetrical – that is, the upload and the download speed is the same.

T-1 circuits are also available at lower speeds.   When the speed of a T-1 is less than 1.54 MB/sec, it is called a “fractional T-1.”   A 56k line is the smallest fractional T-1 available.

Cable:   Cable companies, notably Comcast in Colorado, offer high-speed data services over their cable networks.  The speeds can be impressive—at 1.54mb or above!  The price is generally affordable – as low as $40/month. The down side is that the speed of the service is dependent on the number of customers on your network segment—if there are many customers in your “node” using the network at the same time, performance can be affected.  To further complicate things, cable companies do not guarantee any rates of speed—instead using the generic term “fast” to describe their speed rates.

Cable circuits are asymmetrical – in this case, the download speed is much higher than the upload speed.  Most cable companies limit upload speeds to 128k/sec. or 256k/sec

Wireless:   Using microwaves and other carriers, vendors are able to deliver connectivity via radio waves.  Delivery is limited to line-of-site distances between the transmission tower and a receiver.  In Colorado, there are a few private vendors (Including Netbeam and Shoal Oil) offering wireless Internet connectivity in both rural and urban areas at speeds up to 256k.  Higher download speeds are available for additional fees.

Wireless circuits can be symmetrical – offering identical upload and download speeds.

Satellite:   Using a personal-sized satellite dish, companies such as Direct TV offer download speeds at about 400k/sec.  Satellite connectivity comes in two flavors—the older version could only download data (and required a regular phone line to send Internet requests via an analog modem), but newer versions offer 2-way capability.

Satellite circuits are asymmetrical:   even the new 2-way dishes limit upload speeds to about 128k speeds, but some users have reported speeds as low as 40k for uploading.  They are also subjected to what is known as “latency” – it takes from one to several seconds to bounce the Internet request off of the satellite.

XDSL   family: Where available, DSL service can be a strong price/performance option for libraries.  DSL technology used traditional copper wire and existing phone circuits to deliver high-speed data services at prices that are generally lower than other options.  DSL connectivity speeds generally start at 128/k sec, and can scale up to speeds in excess of a T-1 line)

DSL comes in a variety of flavors that are dependent on the telephone wiring infrastructure in your area.  Distance to a telephone company box called a DSLAM or CO (for Central Office) determines the maximum rate of speed available at your location.

DSL circuits can be either symmetrical or asymmetrical.   The “consumer grade” circuits sold by Qwest in Colorado are generally asymmetrical (limiting upload speeds to 128k on circuits that allow download speeds as high as 500-600k/sec) but for additional fees symmetrical service is available in some areas.  Symmetrical DSL is sometimes referred to as “business class” DSL.  Many smaller phone companies are offering DSL service at competitive rates; check with your local phone company to see if the service is available in your area.

Asynchronous Transfer Mode (ATM): a high speed cell switching service, which is capable of transferring large packets of information such as voice, video, and data over a network.  Because of the quality of service (QOS) and ability to transfer big data loads, the Colorado multi-use network (MNT) selected ATM technology as the network architecture.   To find out more about the MNT and if it is available in your geographic location, see: http://www.colorado.gov/dpa/doit/mnt/, or contact the MNT office directly at 1-866-MNT-COLO