Broadband Internet access, often shortened to just broadband, is a high data rate Internet access—typically contrasted with dial-up access using a 56k modem.
Dial-up modems are limited to a bitrate of less than 56 kbit/s (kilobits per second) and require the full use of a telephone line—whereas broadband technologies supply more than double this rate and generally without disrupting telephone use.
Although various minimum bandwidths have been used in definitions of broadband, ranging up from 64 kbit/s up to 2.0 Mbit/s[1], the 2006 OECD report[2] is typical by defining broadband as having download data transfer rates equal to or faster than 256 kbit/s, while the United States (US) Federal Communications Commission (FCC) as of 2009, defines "Basic Broadband" as data transmission speeds exceeding 768 kilobits per second (Kbps), or 768,000 bits per second, in at least one direction: downstream (from the Internet to the user’s computer) or upstream (from the user’s computer to the Internet).[3] The trend is to raise the threshold of the broadband definition as the marketplace rolls out faster services.[4]
Data rates are defined in terms of maximum download because several common consumer broadband technologies such as ADSL are "asymmetric"—supporting much slower maximum upload data rate than download.
"Broadband penetration" is now treated as a key economic indicator.[2][5]
Contents [hide]
1 Overview
2 Technology
2.1 DSL (ADSL/SDSL)
2.2 Multilinking Modems
2.3 ISDN
2.4 T-1/DS-1
2.5 Wired Ethernet
2.6 Rural broadband
2.7 Satellite Internet
2.8 Cellular broadband
2.9 Power-line Internet
2.10 Wireless ISP
2.11 WorldSpace
3 Pricing in the United States
4 Broadband worldwide
5 See also
5.1 Broadband technologies
5.2 Broadband implementations and standards
5.3 Future broadband implementations
5.4 Broadband applications
5.5 Other
6 References
7 External links
[edit] Overview
Broadband transmission rates Connection Transmission data rate
DS-1 (Tier 1) 1.544 Mbit/s
E-1 2.048 Mbit/s
DS-3 (Tier 3) 44.736 Mbit/s
OC-3 155.52 Mbit/s
OC-12 622.08 Mbit/s
OC-48 2.488 Gbit/s
OC-192 9.953 Gbit/s
OC-768 39.813 Gbit/s
OC-1536 79.6 Gbit/s
OC-3072 159.2 Gbit/s
Broadband is often called "high-speed" access to the Internet, because it usually has a high rate of data transmission. In general, any connection to the customer of 256 kbit/s (0.256 Mbit/s) or greater is more concisely considered broadband Internet access. The International Telecommunication Union Standardization Sector (ITU-T) recommendation I.113 has defined broadband as a transmission capacity that is faster than primary rate ISDN, at 1.5 to 2 Mbit/s. The FCC definition of broadband is 768 kbit/s (0.8 Mbit/s). The Organization for Economic Co-operation and Development (OECD) has defined broadband as 256 kbit/s in at least one direction and this bit rate is the most common baseline that is marketed as "broadband" around the world. There is no specific bitrate defined by the industry, however, and "broadband" can mean lower-bitrate transmission methods. Some Internet Service Providers (ISPs) use this to their advantage in marketing lower-bitrate connections as broadband.
In practice, the advertised bandwidth is not always reliably available to the customer; ISPs often allow a greater number of subscribers than their backbone connection or neighborhood access network can handle, under the assumption that most users will not be using their full connection capacity very frequently. This aggregation strategy works more often than not, so users can typically burst to their full bandwidth most of the time; however, peer-to-peer (P2P) file sharing systems, often requiring extended durations of high bandwidth usage, stress these assumptions, and can cause major problems for ISPs who have excessively overbooked their capacity. For more on this topic, see traffic shaping. As takeup for these introductory products increases, telcos are starting to offer higher bit rate services. For existing connections, this most of the time simply involves reconfiguring the existing equipment at each end of the connection.
As the bandwidth delivered to end users increases, the market expects that video on demand services streamed over the Internet will become more popular, though at the present time such services generally require specialized networks. The data rates on most broadband services still do not suffice to provide good quality video, as MPEG-2 video requires about 6 Mbit/s for good results. Adequate video for some purposes becomes possible at lower data rates, with rates of 768 kbit/s and 384 kbit/s used for some video conferencing applications, and rates as low as 100 kbit/s used for videophones using H.264/MPEG-4 AVC. The MPEG-4 format delivers high-quality video at 2 Mbit/s, at the low end of cable modem and ADSL performance.
Increased bandwidth has already made an impact on newsgroups: postings to groups such as alt.binaries.* have grown from JPEG files to entire CD and DVD images. According to NTL,[disambiguation needed] the level of traffic on their network increased from a daily inbound news feed of 150 gigabytes of data per day and 1 terabyte of data out each day in 2001 to 500 gigabytes of data inbound and over 4 terabytes out each day in 2002.[citation needed]
[edit] Technology
The standard broadband technologies in most areas are DSL and cable modems. Newer technologies in use include VDSL and pushing optical fiber connections closer to the subscriber in both telephone and cable plants. Fiber-optic communication, while only recently being used in fiber to the premises and fiber to the curb schemes, has played a crucial role in enabling Broadband Internet access by making transmission of information over larger distances much more cost-effective than copper wire technology. In a few areas not served by cable or ADSL, community organizations have begun to install Wi-Fi networks, and in some cities and towns local governments are installing municipal Wi-Fi networks. As of 2006, broadband mobile Internet access has become available at the consumer level in some countries, using the HSDPA and EV-DO technologies. The newest technology being deployed for mobile and stationary broadband access is WiMAX.
[edit] DSL (ADSL/SDSL)
Main article: Asymmetric digital subscriber line
[edit] Multilinking Modems
Roughly double the dial-up rate can be achieved with multilinking technology. What is required are two modems, two phone lines, two dial-up accounts, and ISP support for multilinking, or special software at the user end. This inverse multiplexing option was popular with some high-end users before ISDN, DSL and other technologies became available.
Diamond and other vendors had created dual phone line modems with bonding capability. The data rate of dual line modems is faster than 90 kbit/s. The Internet and phone charge will be twice the ordinary dial-up charge.
Load balancing takes two Internet connections and feeds them into your network as one double data rate, more resilient Internet connection. By choosing two independent Internet providers the load balancing hardware will automatically use the line with least load which means should one line fail, the second one automatically takes up the slack.
[edit] ISDN
Integrated Service Digital Network (ISDN) is one of the oldest broadband digital access methods for consumers and businesses to connect to the Internet. It is a telephone data service standard. Its use in the United States peaked in the late 1990s prior to the availability of DSL and cable modem technologies. Broadband service is usually compared to ISDN-BRI because this was the standard broadband access technology that formed a baseline for the challenges faced by the early broadband providers. These providers sought to compete against ISDN by offering faster and cheaper services to consumers.
A basic rate ISDN line (known as ISDN-BRI) is an ISDN line with 2 data "bearer" channels (DS0 - 64 kbit/s each). Using ISDN terminal adapters (erroneously called modems), it is possible to bond together 2 or more separate ISDN-BRI lines to reach bandwidths of 256 kbit/s or more. The ISDN channel bonding technology has been used for video conference applications and broadband data transmission.
Primary rate ISDN, known as ISDN-PRI, is an ISDN line with 23 DS0 channels and total bandwidth of 1,544 kbit/s (US standard). ISDN E1 (European standard) line is an ISDN lines with 30 DS0 channels and total bandwidth of 2,048 kbit/s. Because ISDN is a telephone-based product, a lot of the terminology and physical aspects of the line are shared by the ISDN-PRI used for voice services. An ISDN line can therefore be "provisioned" for voice or data and many different options, depending on the equipment being used at any particular installation, and depending on the offerings of the telephone company's central office switch. Most ISDN-PRI's are used for telephone voice communication using large PBX systems, rather than for data. One obvious exception is that ISPs usually have ISDN-PRI's for handling ISDN data and modem calls.
It is mainly of historical interest that many of the earlier ISDN data lines used 56 kbit/s rather than 64 kbit/s "B" channels of data. This caused ISDN-BRI to be offered at both 128 kbit/s and 112 kbit/s rates, depending on the central office's switching equipment.
Advantages:
Constant data rate at 64 kbit/s for each DS0 channel.
Two way broadband symmetric data transmission, unlike ADSL.
One of the data channels can be used for phone conversation without disturbing the data transmission through the other data channel. When a phone call is ended, the bearer channel can immediately dial and re-connect itself to the data call.
Call setup is very quick.
Low latency
ISDN Voice clarity is unmatched by other phone services.
Caller ID is almost always available for no additional fee.
Maximum distance from the central office is much greater than it is for DSL.
When using ISDN-BRI, there is the possibility of using the low-bandwidth 16 kbit/s "D" channel for packet data and for always on capabilities.
Disadvantages:
ISDN offerings are dwindling in the marketplace due to the widespread use of faster and cheaper alternatives.
ISDN routers, terminal adapters ("modems"), and telephones are more expensive than ordinary POTS equipment, like dial-up modems.
ISDN provisioning can be complicated due to the great number of options available.
ISDN users must dial in to a provider that offers ISDN Internet service, which means that the call could be disconnected.
ISDN is billed as a phone line, to which is added the bill for Internet ISDN access.
"Always on" data connections are not available in all locations.
Some telephone companies charge unusual fees for ISDN, including call setup fees, per minute fees, and higher rates than normal for other services.
[edit] T-1/DS-1
These are highly-regulated services traditionally intended for businesses, that are managed through Public Service Commissions (PSCs) in each state, must be fully defined in PSC tariff documents, and have management rules dating back to the early 1980s which still refer to teletypes as potential connection devices. As such, T-1 services have very strict and rigid service requirements which drive up the provider's maintenance costs and may require them to have a technician on standby 24 hours a day to repair the line if it malfunctions. (In comparison, ISDN and DSL are not regulated by the PSCs at all.) Due to the expensive and regulated nature of T-1 lines, they are normally installed under the provisions of a written agreement, the contract term being typically one to three years. However, there are usually few restrictions to an end-user's use of a T-1, uptime and bandwidth data rates may be guaranteed, quality of service may be supported, and blocks of static IP addresses are commonly included.
Since a T-1 was originally conceived for voice transmission, and voice T-1's are still widely used in businesses, it can be confusing to the uninitiated subscriber. It is often best to refer to the type of T-1 being considered, using the appropriate "data" or "voice" prefix to differentiate between the two. A voice T-1 would terminate at a phone company's central office (CO) for connection to the PSTN; a data T-1 terminates at a point of presence (POP) or data center. The T-1 line which is between a customer's premises and the POP or CO is called the local loop. The owner of the local loop need not be the owner of the network at the POP where your T-1 connects to the Internet, and so a T-1 subscriber may have contracts with these two organizations separately.
The nomenclature for a T-1 varies widely, cited in some circles a DS-1, a T1.5, a T1, or a DS1. Some of these try to distinguish amongst the different aspects of the line, considering the data standard a DS-1, and the physical structure of the trunk line a T-1 or T-1.5. They are also called leased lines, but that terminology is usually for data rates under 1.5 Mbit/s. At times, a T-1 can be included in the term "leased line" or excluded from it. Whatever it is called, it is inherently related to other broadband access methods, which include T-3, SONET OC-3, and other T-carrier and Optical Carriers. Additionally, a T-1 might be aggregated with more than one T-1, producing an nxT-1, such as 4xT-1 which has exactly 4 times the bandwidth of a T-1.
When a T-1 is installed, there are a number of choices to be made: in the carrier chosen, the location of the demarcation point, the type of channel service unit (CSU) or data service unit (DSU) used, the WAN IP router used, the types of bandwidths chosen, etc. Specialized WAN routers are used with T-1 lines that route Internet or VPN data onto the T-1 line from the subscriber's packet-based (TCP/IP) network using customer premises equipment (CPE). The CPE typical consists of a CSU/DSU that converts the DS-1 data stream of the T-1 to a TCP/IP packet data stream for use in the customer's Ethernet LAN. It is noteworthy that many T-1 providers optionally maintain and/or sell the CPE as part of the service contract, which can affect the demarcation point and the ownership of the router, CSU, or DSU.
Although a T-1 has a maximum of 1.544 Mbit/s, a fractional T-1 might be offered which only uses an integer multiple of 128 kbit/s for bandwidth. In this manner, a customer might only purchase 1/12th or 1/3 of a T-1, which would be 128 kbit/s and 512 kbit/s, respectively.
T-1 and fractional T-1 data lines are symmetric, meaning that their upload and download data rates are the same.
[edit] Wired Ethernet
Where available, this method of broadband connection to the Internet would indicate that Internet access is very fast. However, just because Ethernet is offered doesn't mean that the full 10, 100, or 1000 Mbit/s connection can be utilized for direct Internet access. In a college dormitory, for example, the 100 Mbit/s Ethernet access might be fully available to on-campus networks, but Internet access bandwidths might be closer to 4xT-1 data rate (6 Mbit/s). If you are sharing a broadband connection with others in a building, the access bandwidth of the leased line into the building would of course govern the end-user's data rate.
In certain locations, however, true Ethernet broadband access might be available. This would most commonly be the case at a POP or a data center, and not at a typical residence or business. When Ethernet Internet access is offered, it could be fiber-optic or copper twisted pair, and the bandwidth will conform to standard Ethernet data rates of up to 10 Gbit/s. The primary advantage is that no special hardware is needed for Ethernet. Ethernet also has a very low latency.
[edit] Rural broadband
One of the great challenges of broadband is to provide service to potential customers in areas of low population density, such as to farmers, ranchers, and small towns. In cities where the population density is high, it is easy for a service provider to recover equipment costs, but each rural customer may require expensive equipment to get connected.
Several rural broadband solutions exist, though each has its own pitfalls and limitations[clarification needed]. Some choices are better than others, but are dependent on how proactive the local phone company is about upgrading their rural technology.
Wireless Internet Service Provider (WISPs) are rapidly becoming a popular broadband option for rural areas,[citation needed]. The technology's line-of-sight requirements may hamper connectivity in some areas with hilly and heavily foliated terrain. However, the Tegola project, a successful pilot in remote Scotland, demonstrates that wireless can be a viable option[6]. In addition, compared to hard-wired connectivity, there are security risks (unless robust security protocols are enabled); speeds are significantly slower (2 – 50 times slower); and the network can be less stable, due to interference from other wireless devices, weather and line-of-sight problems.Al[7]
Dial-up modems are limited to a bitrate of less than 56 kbit/s (kilobits per second) and require the full use of a telephone line—whereas broadband technologies supply more than double this rate and generally without disrupting telephone use.
Although various minimum bandwidths have been used in definitions of broadband, ranging up from 64 kbit/s up to 2.0 Mbit/s[1], the 2006 OECD report[2] is typical by defining broadband as having download data transfer rates equal to or faster than 256 kbit/s, while the United States (US) Federal Communications Commission (FCC) as of 2009, defines "Basic Broadband" as data transmission speeds exceeding 768 kilobits per second (Kbps), or 768,000 bits per second, in at least one direction: downstream (from the Internet to the user’s computer) or upstream (from the user’s computer to the Internet).[3] The trend is to raise the threshold of the broadband definition as the marketplace rolls out faster services.[4]
Data rates are defined in terms of maximum download because several common consumer broadband technologies such as ADSL are "asymmetric"—supporting much slower maximum upload data rate than download.
"Broadband penetration" is now treated as a key economic indicator.[2][5]
Contents [hide]
1 Overview
2 Technology
2.1 DSL (ADSL/SDSL)
2.2 Multilinking Modems
2.3 ISDN
2.4 T-1/DS-1
2.5 Wired Ethernet
2.6 Rural broadband
2.7 Satellite Internet
2.8 Cellular broadband
2.9 Power-line Internet
2.10 Wireless ISP
2.11 WorldSpace
3 Pricing in the United States
4 Broadband worldwide
5 See also
5.1 Broadband technologies
5.2 Broadband implementations and standards
5.3 Future broadband implementations
5.4 Broadband applications
5.5 Other
6 References
7 External links
[edit] Overview
Broadband transmission rates Connection Transmission data rate
DS-1 (Tier 1) 1.544 Mbit/s
E-1 2.048 Mbit/s
DS-3 (Tier 3) 44.736 Mbit/s
OC-3 155.52 Mbit/s
OC-12 622.08 Mbit/s
OC-48 2.488 Gbit/s
OC-192 9.953 Gbit/s
OC-768 39.813 Gbit/s
OC-1536 79.6 Gbit/s
OC-3072 159.2 Gbit/s
Broadband is often called "high-speed" access to the Internet, because it usually has a high rate of data transmission. In general, any connection to the customer of 256 kbit/s (0.256 Mbit/s) or greater is more concisely considered broadband Internet access. The International Telecommunication Union Standardization Sector (ITU-T) recommendation I.113 has defined broadband as a transmission capacity that is faster than primary rate ISDN, at 1.5 to 2 Mbit/s. The FCC definition of broadband is 768 kbit/s (0.8 Mbit/s). The Organization for Economic Co-operation and Development (OECD) has defined broadband as 256 kbit/s in at least one direction and this bit rate is the most common baseline that is marketed as "broadband" around the world. There is no specific bitrate defined by the industry, however, and "broadband" can mean lower-bitrate transmission methods. Some Internet Service Providers (ISPs) use this to their advantage in marketing lower-bitrate connections as broadband.
In practice, the advertised bandwidth is not always reliably available to the customer; ISPs often allow a greater number of subscribers than their backbone connection or neighborhood access network can handle, under the assumption that most users will not be using their full connection capacity very frequently. This aggregation strategy works more often than not, so users can typically burst to their full bandwidth most of the time; however, peer-to-peer (P2P) file sharing systems, often requiring extended durations of high bandwidth usage, stress these assumptions, and can cause major problems for ISPs who have excessively overbooked their capacity. For more on this topic, see traffic shaping. As takeup for these introductory products increases, telcos are starting to offer higher bit rate services. For existing connections, this most of the time simply involves reconfiguring the existing equipment at each end of the connection.
As the bandwidth delivered to end users increases, the market expects that video on demand services streamed over the Internet will become more popular, though at the present time such services generally require specialized networks. The data rates on most broadband services still do not suffice to provide good quality video, as MPEG-2 video requires about 6 Mbit/s for good results. Adequate video for some purposes becomes possible at lower data rates, with rates of 768 kbit/s and 384 kbit/s used for some video conferencing applications, and rates as low as 100 kbit/s used for videophones using H.264/MPEG-4 AVC. The MPEG-4 format delivers high-quality video at 2 Mbit/s, at the low end of cable modem and ADSL performance.
Increased bandwidth has already made an impact on newsgroups: postings to groups such as alt.binaries.* have grown from JPEG files to entire CD and DVD images. According to NTL,[disambiguation needed] the level of traffic on their network increased from a daily inbound news feed of 150 gigabytes of data per day and 1 terabyte of data out each day in 2001 to 500 gigabytes of data inbound and over 4 terabytes out each day in 2002.[citation needed]
[edit] Technology
The standard broadband technologies in most areas are DSL and cable modems. Newer technologies in use include VDSL and pushing optical fiber connections closer to the subscriber in both telephone and cable plants. Fiber-optic communication, while only recently being used in fiber to the premises and fiber to the curb schemes, has played a crucial role in enabling Broadband Internet access by making transmission of information over larger distances much more cost-effective than copper wire technology. In a few areas not served by cable or ADSL, community organizations have begun to install Wi-Fi networks, and in some cities and towns local governments are installing municipal Wi-Fi networks. As of 2006, broadband mobile Internet access has become available at the consumer level in some countries, using the HSDPA and EV-DO technologies. The newest technology being deployed for mobile and stationary broadband access is WiMAX.
[edit] DSL (ADSL/SDSL)
Main article: Asymmetric digital subscriber line
[edit] Multilinking Modems
Roughly double the dial-up rate can be achieved with multilinking technology. What is required are two modems, two phone lines, two dial-up accounts, and ISP support for multilinking, or special software at the user end. This inverse multiplexing option was popular with some high-end users before ISDN, DSL and other technologies became available.
Diamond and other vendors had created dual phone line modems with bonding capability. The data rate of dual line modems is faster than 90 kbit/s. The Internet and phone charge will be twice the ordinary dial-up charge.
Load balancing takes two Internet connections and feeds them into your network as one double data rate, more resilient Internet connection. By choosing two independent Internet providers the load balancing hardware will automatically use the line with least load which means should one line fail, the second one automatically takes up the slack.
[edit] ISDN
Integrated Service Digital Network (ISDN) is one of the oldest broadband digital access methods for consumers and businesses to connect to the Internet. It is a telephone data service standard. Its use in the United States peaked in the late 1990s prior to the availability of DSL and cable modem technologies. Broadband service is usually compared to ISDN-BRI because this was the standard broadband access technology that formed a baseline for the challenges faced by the early broadband providers. These providers sought to compete against ISDN by offering faster and cheaper services to consumers.
A basic rate ISDN line (known as ISDN-BRI) is an ISDN line with 2 data "bearer" channels (DS0 - 64 kbit/s each). Using ISDN terminal adapters (erroneously called modems), it is possible to bond together 2 or more separate ISDN-BRI lines to reach bandwidths of 256 kbit/s or more. The ISDN channel bonding technology has been used for video conference applications and broadband data transmission.
Primary rate ISDN, known as ISDN-PRI, is an ISDN line with 23 DS0 channels and total bandwidth of 1,544 kbit/s (US standard). ISDN E1 (European standard) line is an ISDN lines with 30 DS0 channels and total bandwidth of 2,048 kbit/s. Because ISDN is a telephone-based product, a lot of the terminology and physical aspects of the line are shared by the ISDN-PRI used for voice services. An ISDN line can therefore be "provisioned" for voice or data and many different options, depending on the equipment being used at any particular installation, and depending on the offerings of the telephone company's central office switch. Most ISDN-PRI's are used for telephone voice communication using large PBX systems, rather than for data. One obvious exception is that ISPs usually have ISDN-PRI's for handling ISDN data and modem calls.
It is mainly of historical interest that many of the earlier ISDN data lines used 56 kbit/s rather than 64 kbit/s "B" channels of data. This caused ISDN-BRI to be offered at both 128 kbit/s and 112 kbit/s rates, depending on the central office's switching equipment.
Advantages:
Constant data rate at 64 kbit/s for each DS0 channel.
Two way broadband symmetric data transmission, unlike ADSL.
One of the data channels can be used for phone conversation without disturbing the data transmission through the other data channel. When a phone call is ended, the bearer channel can immediately dial and re-connect itself to the data call.
Call setup is very quick.
Low latency
ISDN Voice clarity is unmatched by other phone services.
Caller ID is almost always available for no additional fee.
Maximum distance from the central office is much greater than it is for DSL.
When using ISDN-BRI, there is the possibility of using the low-bandwidth 16 kbit/s "D" channel for packet data and for always on capabilities.
Disadvantages:
ISDN offerings are dwindling in the marketplace due to the widespread use of faster and cheaper alternatives.
ISDN routers, terminal adapters ("modems"), and telephones are more expensive than ordinary POTS equipment, like dial-up modems.
ISDN provisioning can be complicated due to the great number of options available.
ISDN users must dial in to a provider that offers ISDN Internet service, which means that the call could be disconnected.
ISDN is billed as a phone line, to which is added the bill for Internet ISDN access.
"Always on" data connections are not available in all locations.
Some telephone companies charge unusual fees for ISDN, including call setup fees, per minute fees, and higher rates than normal for other services.
[edit] T-1/DS-1
These are highly-regulated services traditionally intended for businesses, that are managed through Public Service Commissions (PSCs) in each state, must be fully defined in PSC tariff documents, and have management rules dating back to the early 1980s which still refer to teletypes as potential connection devices. As such, T-1 services have very strict and rigid service requirements which drive up the provider's maintenance costs and may require them to have a technician on standby 24 hours a day to repair the line if it malfunctions. (In comparison, ISDN and DSL are not regulated by the PSCs at all.) Due to the expensive and regulated nature of T-1 lines, they are normally installed under the provisions of a written agreement, the contract term being typically one to three years. However, there are usually few restrictions to an end-user's use of a T-1, uptime and bandwidth data rates may be guaranteed, quality of service may be supported, and blocks of static IP addresses are commonly included.
Since a T-1 was originally conceived for voice transmission, and voice T-1's are still widely used in businesses, it can be confusing to the uninitiated subscriber. It is often best to refer to the type of T-1 being considered, using the appropriate "data" or "voice" prefix to differentiate between the two. A voice T-1 would terminate at a phone company's central office (CO) for connection to the PSTN; a data T-1 terminates at a point of presence (POP) or data center. The T-1 line which is between a customer's premises and the POP or CO is called the local loop. The owner of the local loop need not be the owner of the network at the POP where your T-1 connects to the Internet, and so a T-1 subscriber may have contracts with these two organizations separately.
The nomenclature for a T-1 varies widely, cited in some circles a DS-1, a T1.5, a T1, or a DS1. Some of these try to distinguish amongst the different aspects of the line, considering the data standard a DS-1, and the physical structure of the trunk line a T-1 or T-1.5. They are also called leased lines, but that terminology is usually for data rates under 1.5 Mbit/s. At times, a T-1 can be included in the term "leased line" or excluded from it. Whatever it is called, it is inherently related to other broadband access methods, which include T-3, SONET OC-3, and other T-carrier and Optical Carriers. Additionally, a T-1 might be aggregated with more than one T-1, producing an nxT-1, such as 4xT-1 which has exactly 4 times the bandwidth of a T-1.
When a T-1 is installed, there are a number of choices to be made: in the carrier chosen, the location of the demarcation point, the type of channel service unit (CSU) or data service unit (DSU) used, the WAN IP router used, the types of bandwidths chosen, etc. Specialized WAN routers are used with T-1 lines that route Internet or VPN data onto the T-1 line from the subscriber's packet-based (TCP/IP) network using customer premises equipment (CPE). The CPE typical consists of a CSU/DSU that converts the DS-1 data stream of the T-1 to a TCP/IP packet data stream for use in the customer's Ethernet LAN. It is noteworthy that many T-1 providers optionally maintain and/or sell the CPE as part of the service contract, which can affect the demarcation point and the ownership of the router, CSU, or DSU.
Although a T-1 has a maximum of 1.544 Mbit/s, a fractional T-1 might be offered which only uses an integer multiple of 128 kbit/s for bandwidth. In this manner, a customer might only purchase 1/12th or 1/3 of a T-1, which would be 128 kbit/s and 512 kbit/s, respectively.
T-1 and fractional T-1 data lines are symmetric, meaning that their upload and download data rates are the same.
[edit] Wired Ethernet
Where available, this method of broadband connection to the Internet would indicate that Internet access is very fast. However, just because Ethernet is offered doesn't mean that the full 10, 100, or 1000 Mbit/s connection can be utilized for direct Internet access. In a college dormitory, for example, the 100 Mbit/s Ethernet access might be fully available to on-campus networks, but Internet access bandwidths might be closer to 4xT-1 data rate (6 Mbit/s). If you are sharing a broadband connection with others in a building, the access bandwidth of the leased line into the building would of course govern the end-user's data rate.
In certain locations, however, true Ethernet broadband access might be available. This would most commonly be the case at a POP or a data center, and not at a typical residence or business. When Ethernet Internet access is offered, it could be fiber-optic or copper twisted pair, and the bandwidth will conform to standard Ethernet data rates of up to 10 Gbit/s. The primary advantage is that no special hardware is needed for Ethernet. Ethernet also has a very low latency.
[edit] Rural broadband
One of the great challenges of broadband is to provide service to potential customers in areas of low population density, such as to farmers, ranchers, and small towns. In cities where the population density is high, it is easy for a service provider to recover equipment costs, but each rural customer may require expensive equipment to get connected.
Several rural broadband solutions exist, though each has its own pitfalls and limitations[clarification needed]. Some choices are better than others, but are dependent on how proactive the local phone company is about upgrading their rural technology.
Wireless Internet Service Provider (WISPs) are rapidly becoming a popular broadband option for rural areas,[citation needed]. The technology's line-of-sight requirements may hamper connectivity in some areas with hilly and heavily foliated terrain. However, the Tegola project, a successful pilot in remote Scotland, demonstrates that wireless can be a viable option[6]. In addition, compared to hard-wired connectivity, there are security risks (unless robust security protocols are enabled); speeds are significantly slower (2 – 50 times slower); and the network can be less stable, due to interference from other wireless devices, weather and line-of-sight problems.Al[7]
source:http://en.wikipedia.org/wiki/Broadband_Internet_access
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