What is DSL?

DSL is a wonderful service however if you want a solid connection with a service level agreement that includes faster trouble shooting and quicker problem resolution if your line goes down then we recommend a T1 Connection with a business service level agreement.

A detractor from DSL service is that there is no guarantee that the service won't lag with the addition of new users. Most DSL Internet providers will tell you that a single DSL business line shouldn't support more than 20 people, although a more realistic number would be around 10. Even with 10 users, there will be slowdowns if everyone is transferring data.

DSL is a technology for bringing high-bandwidth information to homes and small businesses over ordinary telephone lines. There are numerous different variations of DSL, such as ADSL, HDSL, IDSL, VDSL and RADSL.


DSL stands for Digital Subscriber Line. Digital Subscriber Line technology allows for the transmission of information (voice, video and data), over existing copper telephone lines at incredible speeds. DSL uses your ordinary phone line and you are always connected and for you that means no more waiting for someone in the household to get off the phone. DSL offers users a choice of speeds ranging from 144 Kbps to 1.5Mbps. This is 2.5x to 25x times faster than a standard 56Kbps dial-up modem. DSL technology uses existing 2-wire copper telephone wiring to deliver high-speed data services to homes and businesses. It must be noted that there is a higher SLA (service level agreement) for T1 service or SDSL service which is considered business class service versus ADSL which is considered to be residential class service.

Over any given line, the maximum DSL speed is determined by the distance between the customer site and the Central Office (CO). Most ISP's offer Symmetric DSL (SDSL) data services at speeds that vary from 144 Kbps to 1.54 Mbps, and now even faster up to 6.0 Mbps--so customers can choose the rate that meets their specific needs. At the customer premises, a DSL router or modem connects the DSL line to a local-area network (LAN) or an individual computer. Once installed, the DSL router provides the customer site with continuous connection to the Internet and use of the telephone at the same time.

 

 DSL definitions made easy.
ADSL (Asymmetric Digital Subscriber Line) is quickly becoming the most popular form of xDSL. ADSL supports up to 8 Mbps bandwidth for downloading and up to 1 Mbps for uploading. The asymmetrical nature of ADSL technology makes it ideal for Internet/Intranet surfing, video-on-demand, and remote local area network (LAN) access. Users of ADSL typically download more information than they send.

ADSL requires a voice/data splitter, commonly called a POTS Splitter (Plain Old Telephone Service) to be installed at the consumer's home or business location. The splitter separates voice from data transmissions. For simultaneous use of the telephone and data access, additional phone wires may need to be installed at your location. Full rate ADSL provides service up to a maximum range of 12,000 feet (about 2.0 miles) from the telecommunication provider company's central office to the end-user.

ADSL Lite technology often called Splitterless, G.lite or Universal ADSL and now also known as G.992.2 does not require a POTS splitter to be installed at the consumer's home or business. ADSL Lite provides bandwidth downstream up to 1.5 Mbps and upstream up to 512 kbps. ADSL Lite provides service up to a maximum range of 12,000 feet (about 2.0 miles) from the central office.
 

SDSL (Symmetrical Digital Subscriber Line) delivers high-speed data networking over a single-pair of copper phone lines, at the same speed in both the upstream and downstream directions. Speed ranges from 160 Kbps up to 1.544 Mbps at a maximum range of 15,000 feet (about 2.8 miles). SDSL is ideal for business applications that require identical downstream and upstream speeds such as video conferencing or collaborative computing as well as similar applications appropriate for ADSL technology. SDSL uses the same kind of line-modulation technique employed in ISDN, known as 2B1Q.
 

HDSL (High bit-rate Digital Subscriber Line) delivers high-speed data networking up to 1.544 Mbps over two copper pairs and up to 2.048 Mbps over three pairs at a maximum range of 20,000 feet (about 3.8 miles) from a central office. It is similar to SDSL and has symmetrical transmission capabilities. Most T1 lines installed today utilize this technology.


IDSL (ISDN Digital Subscriber Line) provides symmetric download and upload speeds from 64 to 144 Kbps on a single pair of copper wires. The maximum range of IDSL from a central office is 39,600 feet (about 7.5 miles), but this can be doubled with a mid-span "U" loop repeater. IDSL uses 2B1Q line coding, the same kind of line-modulation technique employed in SDSL, and ISDN.
 

VDSL (Very high bit-rate Digital Subscriber Line) is the fastest xDSL technology, delivering downloads up to 13-52 Mbps and uploads at 1.5 to 2.3 Mbps over a single pair of copper wires. However, VDSL is limited to a maximum range of 1,000 to 4,500 feet (about .2-.9 miles) or 1.6-7.2km from the central office, depending upon the speed.

Information below taken from Velocity Guide.

http://www.velocityguide.com/dsl/dedicated-t1-vs-dsl.html

DSL is one of the top two consumer broadband Internet access choices. Used by more than 50 million Americans, DSL has become a common technology that has been fully embraced by a satisfied marketplace. DSL has been so successful in fact many businesses have turned to it for networked Internet access for an entire office. This type of business service has been relegated to Telcos and their T1 offerings for years.

So the question has become, what is better for business Internet access, a DSL line or a T1? To answer this we will look at both services and compare.

DSL Internet Access For Business
DSL Internet for business uses the same technology that the residential service utilizes. A digital line along with compression protocols is used to get faster throughput with uploads at around 256k and downloads all the way up to 3MB depending upon location. The business service suffers from distance in the same way residential access does, although filters and signal amplifiers can be used to help out in this regard. If the business is too far from the central Telco office however, service will be spotty and the number of users it can support will decrease, as will the throughput speeds.

DSL Business Internet pricing is reasonable for what it offers, and its not too far beyond residential prices. Ranging from around $69 all the way up to $300 dollars per month, this bandwidth is affordable and the hardware is inexpensive. The price increase includes an increase in bandwidth as well as total data throughput, so if your business plans on sending and receiving more than 40GB per month, the higher end services are what you need.


A detractor from DSL service is that there is no guarantee that the service won't lag with the addition of new users. Most DSL Internet providers will tell you that a single DSL business line shouldn't support more than 20 people, although a more realistic number would be around 10. Even with 10 users, there will be slowdowns if everyone is transferring data.

Dedicated T1 Internet Service
T1s are large pipes used to transport digital voice and data signals from a business location to the respective media requested. This service can hand a great deal of bandwidth, both voice and data, and has 24 fixed channels to send information over. T1s were used exclusively by phone companies to carry voice traffic until the huge increase in Internet traffic in the mid 1990's.

Businesses can now lease a full T1 that will provide 1.54 MB of connectivity with the flexibility to assign the available channels to voice or data. This is guaranteed throughput that can support up to 50 users comfortably, with each user having their own bandwidth so as not to slow down other users.

From a technical standpoint, a T1 shouldn't be managed in house as the phone company will be the only ones that can really set up and configure it. This can be good and bad depending on how often you wish to make changes to the line. These changes do not include adding or removing users, which can be done by a network administrator at any time with little to no trouble.

From a pricing standpoint the T1 is a great deal more expensive than DSL. Ranging between $599 up to $2000 per month, with a set up fee that varies between free and $500 the cost of the T1 will be prohibitive to smaller businesses. With the guaranteed bandwidth and associated features, the service is well worth the price.
 

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