Computer Science WK 3 Assignment

11

Internet Access Using Broadband And Wireless

11.1 Introduction

The previous chapter described the Internet as a network of networks. For most in- dividuals, however, the main question is not how the Internet is built, but how they can connect and use it. This chapter describes technologies used for Internet connections, and explains what each provides.

11.2 Access Technologies For The Last Mile

The question arises, what technology provides the best connection between a custo- mer and an ISP? The answer depends on the physical distance spanned, the data rate the customer desires, and other factors, such as whether the location is rural or metro- politan. Industry professionals use the term last mile to refer to such connections, even though the distance is often greater than a mile. To emphasize that they are designed to provide Internet access, technologies used for the last mile are known as access techno- logies, and include:

Dial-up Leased data circuit (copper and optical fiber) Digital Subscriber Line (DSL) Cable modem Wi-Fi 4G and 5G wireless

121

11

Internet Access Using Broadband And Wireless

11.1 Introduction

The previous chapter described the Internet as a network of networks. For most in- dividuals, however, the main question is not how the Internet is built, but how they can connect and use it. This chapter describes technologies used for Internet connections, and explains what each provides.

11.2 Access Technologies For The Last Mile

The question arises, what technology provides the best connection between a custo- mer and an ISP? The answer depends on the physical distance spanned, the data rate the customer desires, and other factors, such as whether the location is rural or metro- politan. Industry professionals use the term last mile to refer to such connections, even though the distance is often greater than a mile. To emphasize that they are designed to provide Internet access, technologies used for the last mile are known as access techno- logies, and include:

Dial-up Leased data circuit (copper and optical fiber) Digital Subscriber Line (DSL) Cable modem Wi-Fi 4G and 5G wireless

121

K392894.indd 149 03/08/18 12:07 pmComer, Douglas E.. The Internet Book : Everything You Need to Know about Computer Networking and How the Internet Works, CRC Press LLC, 2018. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/apus/detail.action?docID=5502790. Created from apus on 2025-01-23 05:39:01.

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122 Internet Access Using Broadband And Wireless Chap. 11

11.3 Dial-up Internet Access

Early Internet Service Providers offered dial-up access. The mechanism is straightforward: a dial-up modem connects between a computer and an analog voice telephone system. The modem plugs in just like a telephone. The computer can in- struct the modem to go off hook (i.e., emulate picking up a handset), detect a dial tone, dial a specified number, and wait for the other end to answer. An ISP gives each user software that controls the modem and dials a special phone number at the ISP. The special number doesn’t go to telephones, but to a set of modems. Whenever the number is called, one of the modems answers. The user’s modem communicates with the modem at the ISP, and to send data, the two modems modulate audible tones. Figure 11.1 illustrates the technology.

Landline (Voice) Telephone

System

user’s computer

ISP’s computer attached to the Internet

User’s dial-up modem ISP’s dial-up modem

ISP’s Internet connection

Figure 11.1 Illustration of the equipment used for dial-up Internet access. A modem attached to a user’s computer calls a modem at the ISP.

11.4 Narrowband And Broadband Access

Dial-up Internet access has the advantage of using relatively inexpensive equip- ment (a dial-up modem), and being trivial to install (a user simply plugs the modem into a standard landline telephone outlet). However, dial-up is classified as a nar- rowband technology, which means that it transfers data slowly. Early modems operated at 300 bits per second or slower; by the late 1990s, techniques had been invented that enabled transfers of up to 56,000 bits per second. Narrowband technology means a user must wait a long time for even the simplest request (e.g., a web page to appear).

Starting in the 1990s, a set of technologies appeared that could transfer millions of bits per second. The technologies are classified as broadband technologies to em- phasize that they can transfer data significantly faster than narrowband technologies. Once broadband service became available, users immediately saw the advantage and switched from dial-up to a broadband service. Although still used when broadband is not available, dial-up access has largely been replaced. We can summarize:

Early Internet access used narrowband dial-up technologies; most users abandoned dial-up when faster broadband technologies became available.

Sec. 11.4 Narrowband And Broadband Access 123

11.5 Leased Data Circuit Access

Until the mid-1990s, only one broadband access technology was available: a digital circuit leased from a common carrier. In essence, leasing a circuit means renting unused wires in cables that were originally set up for phone service, and then placing a modem at each end. Leased circuits are classified as point to point because the circuit starts at a specified geographic location and runs to another geographic location. Leased circuits are also called dedicated circuits because a leased circuit is not shared with other users (i.e., a customer who rents the circuit has exclusive access, even if the circuit crosses a long distance and the path runs through many intermediate cities).

Leased circuits are expensive. A customer must pay an initial fee to have a circuit installed, and then must pay a monthly fee for use of the circuit. The fee depends on the distance and the data rate the circuit supports, but fees are much higher than other broadband access technologies. Consequently, only large business customers or ISPs lease circuits. In terms of data rates, a wide range is available. In the U.S., for exam- ple, a T1 can transfer 1.54 million bits per second; an OC-192 circuit can transfer 10 billion bits per second.†

11.6 Digital Subscriber Line (DSL) Access

Before the Internet first emerged, the telephone industry had wiring in place to most homes and businesses. Phone companies investigated ways their landline phone wiring could be used to transfer digital data. Researchers found ways to send digital data over the phone wires that were designed to carry analog voice signals, and devised a set of technologies that varied in the data rates available and the distance spanned. Known as Digital Subscriber Line (DSL) technologies, the technologies are classified as broadband because they offer much higher data rates than dial-up. The actual data rate DSL can deliver depends on the distance between a subscriber and the telephone switching center. However, download data rates of over two million bits per second are common, over thirty times more bits per second than dial-up.

The most interesting aspect of DSL is that when filters are used, data and voice calls can pass over the same wires simultaneously without interfering with one another. Figure 11.2 illustrates the equipment used at the subscriber’s site and the phone com- pany.

user’s telephone

computer voice system

DSL modem

wires carry both voice and DSL signals

DSL filter

User’s DSL modem Splitter divides signals

into voice and DSL

Figure 11.2 Illustration of the equipment used with DSL access.

†Higher speed circuits use optical fiber rather than copper wires.

K392894.indd 150 03/08/18 12:07 pmComer, Douglas E.. The Internet Book : Everything You Need to Know about Computer Networking and How the Internet Works, CRC Press LLC, 2018. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/apus/detail.action?docID=5502790. Created from apus on 2025-01-23 05:39:01.

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122 Internet Access Using Broadband And Wireless Chap. 11

11.3 Dial-up Internet Access

Early Internet Service Providers offered dial-up access. The mechanism is straightforward: a dial-up modem connects between a computer and an analog voice telephone system. The modem plugs in just like a telephone. The computer can in- struct the modem to go off hook (i.e., emulate picking up a handset), detect a dial tone, dial a specified number, and wait for the other end to answer. An ISP gives each user software that controls the modem and dials a special phone number at the ISP. The special number doesn’t go to telephones, but to a set of modems. Whenever the number is called, one of the modems answers. The user’s modem communicates with the modem at the ISP, and to send data, the two modems modulate audible tones. Figure 11.1 illustrates the technology.

Landline (Voice) Telephone

System

user’s computer

ISP’s computer attached to the Internet

User’s dial-up modem ISP’s dial-up modem

ISP’s Internet connection

Figure 11.1 Illustration of the equipment used for dial-up Internet access. A modem attached to a user’s computer calls a modem at the ISP.

11.4 Narrowband And Broadband Access

Dial-up Internet access has the advantage of using relatively inexpensive equip- ment (a dial-up modem), and being trivial to install (a user simply plugs the modem into a standard landline telephone outlet). However, dial-up is classified as a nar- rowband technology, which means that it transfers data slowly. Early modems operated at 300 bits per second or slower; by the late 1990s, techniques had been invented that enabled transfers of up to 56,000 bits per second. Narrowband technology means a user must wait a long time for even the simplest request (e.g., a web page to appear).

Starting in the 1990s, a set of technologies appeared that could transfer millions of bits per second. The technologies are classified as broadband technologies to em- phasize that they can transfer data significantly faster than narrowband technologies. Once broadband service became available, users immediately saw the advantage and switched from dial-up to a broadband service. Although still used when broadband is not available, dial-up access has largely been replaced. We can summarize:

Early Internet access used narrowband dial-up technologies; most users abandoned dial-up when faster broadband technologies became available.

Sec. 11.4 Narrowband And Broadband Access 123

11.5 Leased Data Circuit Access

Until the mid-1990s, only one broadband access technology was available: a digital circuit leased from a common carrier. In essence, leasing a circuit means renting unused wires in cables that were originally set up for phone service, and then placing a modem at each end. Leased circuits are classified as point to point because the circuit starts at a specified geographic location and runs to another geographic location. Leased circuits are also called dedicated circuits because a leased circuit is not shared with other users (i.e., a customer who rents the circuit has exclusive access, even if the circuit crosses a long distance and the path runs through many intermediate cities).

Leased circuits are expensive. A customer must pay an initial fee to have a circuit installed, and then must pay a monthly fee for use of the circuit. The fee depends on the distance and the data rate the circuit supports, but fees are much higher than other broadband access technologies. Consequently, only large business customers or ISPs lease circuits. In terms of data rates, a wide range is available. In the U.S., for exam- ple, a T1 can transfer 1.54 million bits per second; an OC-192 circuit can transfer 10 billion bits per second.†

11.6 Digital Subscriber Line (DSL) Access

Before the Internet first emerged, the telephone industry had wiring in place to most homes and businesses. Phone companies investigated ways their landline phone wiring could be used to transfer digital data. Researchers found ways to send digital data over the phone wires that were designed to carry analog voice signals, and devised a set of technologies that varied in the data rates available and the distance spanned. Known as Digital Subscriber Line (DSL) technologies, the technologies are classified as broadband because they offer much higher data rates than dial-up. The actual data rate DSL can deliver depends on the distance between a subscriber and the telephone switching center. However, download data rates of over two million bits per second are common, over thirty times more bits per second than dial-up.

The most interesting aspect of DSL is that when filters are used, data and voice calls can pass over the same wires simultaneously without interfering with one another. Figure 11.2 illustrates the equipment used at the subscriber’s site and the phone com- pany.

user’s telephone

computer voice system

DSL modem

wires carry both voice and DSL signals

DSL filter

User’s DSL modem Splitter divides signals

into voice and DSL

Figure 11.2 Illustration of the equipment used with DSL access.

†Higher speed circuits use optical fiber rather than copper wires.

122 Internet Access Using Broadband And Wireless Chap. 11

11.3 Dial-up Internet Access

Early Internet Service Providers offered dial-up access. The mechanism is straightforward: a dial-up modem connects between a computer and an analog voice telephone system. The modem plugs in just like a telephone. The computer can in- struct the modem to go off hook (i.e., emulate picking up a handset), detect a dial tone, dial a specified number, and wait for the other end to answer. An ISP gives each user software that controls the modem and dials a special phone number at the ISP. The special number doesn’t go to telephones, but to a set of modems. Whenever the number is called, one of the modems answers. The user’s modem communicates with the modem at the ISP, and to send data, the two modems modulate audible tones. Figure 11.1 illustrates the technology.

Landline (Voice) Telephone

System

user’s computer

ISP’s computer attached to the Internet

User’s dial-up modem ISP’s dial-up modem

ISP’s Internet connection

Figure 11.1 Illustration of the equipment used for dial-up Internet access. A modem attached to a user’s computer calls a modem at the ISP.

11.4 Narrowband And Broadband Access

Dial-up Internet access has the advantage of using relatively inexpensive equip- ment (a dial-up modem), and being trivial to install (a user simply plugs the modem into a standard landline telephone outlet). However, dial-up is classified as a nar- rowband technology, which means that it transfers data slowly. Early modems operated at 300 bits per second or slower; by the late 1990s, techniques had been invented that enabled transfers of up to 56,000 bits per second. Narrowband technology means a user must wait a long time for even the simplest request (e.g., a web page to appear).

Starting in the 1990s, a set of technologies appeared that could transfer millions of bits per second. The technologies are classified as broadband technologies to em- phasize that they can transfer data significantly faster than narrowband technologies. Once broadband service became available, users immediately saw the advantage and switched from dial-up to a broadband service. Although still used when broadband is not available, dial-up access has largely been replaced. We can summarize:

Early Internet access used narrowband dial-up technologies; most users abandoned dial-up when faster broadband technologies became available.

Sec. 11.4 Narrowband And Broadband Access 123

11.5 Leased Data Circuit Access

Until the mid-1990s, only one broadband access technology was available: a digital circuit leased from a common carrier. In essence, leasing a circuit means renting unused wires in cables that were originally set up for phone service, and then placing a modem at each end. Leased circuits are classified as point to point because the circuit starts at a specified geographic location and runs to another geographic location. Leased circuits are also called dedicated circuits because a leased circuit is not shared with other users (i.e., a customer who rents the circuit has exclusive access, even if the circuit crosses a long distance and the path runs through many intermediate cities).

Leased circuits are expensive. A customer must pay an initial fee to have a circuit installed, and then must pay a monthly fee for use of the circuit. The fee depends on the distance and the data rate the circuit supports, but fees are much higher than other broadband access technologies. Consequently, only large business customers or ISPs lease circuits. In terms of data rates, a wide range is available. In the U.S., for exam- ple, a T1 can transfer 1.54 million bits per second; an OC-192 circuit can transfer 10 billion bits per second.†

11.6 Digital Subscriber Line (DSL) Access

Before the Internet first emerged, the telephone industry had wiring in place to most homes and businesses. Phone companies investigated ways their landline phone wiring could be used to transfer digital data. Researchers found ways to send digital data over the phone wires that were designed to carry analog voice signals, and devised a set of technologies that varied in the data rates available and the distance spanned. Known as Digital Subscriber Line (DSL) technologies, the technologies are classified as broadband because they offer much higher data rates than dial-up. The actual data rate DSL can deliver depends on the distance between a subscriber and the telephone switching center. However, download data rates of over two million bits per second are common, over thirty times more bits per second than dial-up.

The most interesting aspect of DSL is that when filters are used, data and voice calls can pass over the same wires simultaneously without interfering with one another. Figure 11.2 illustrates the equipment used at the subscriber’s site and the phone com- pany.

user’s telephone

computer voice system

DSL modem

wires carry both voice and DSL signals

DSL filter

User’s DSL modem Splitter divides signals

into voice and DSL

Figure 11.2 Illustration of the equipment used with DSL access.

†Higher speed circuits use optical fiber rather than copper wires.

K392894.indd 151 03/08/18 12:07 pmComer, Douglas E.. The Internet Book : Everything You Need to Know about Computer Networking and How the Internet Works, CRC Press LLC, 2018. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/apus/detail.action?docID=5502790. Created from apus on 2025-01-23 05:39:01.

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124 Internet Access Using Broadband And Wireless Chap. 11

As Figure 11.2 shows, only one set of wires connects a user with the telephone switching center. Technically, a DSL modem sends data using higher frequencies than a voice call. At the switching center, a small device known as a splitter separates the sig- nals so that voice signals can be sent to the voice telephone system and DSL signals can be sent to a DSL modem that connects to the Internet. At the user’s location, a splitter (also known as a DSL filter) prevents a user’s telephone from generating random signals that could interfere with DSL. The point is:

Although it uses the same wiring as a conventional landline telephone, DSL offers much higher data transfer rates than dial-up access. Furthermore, splitters allow conventional telephone calls and data transfer to proceed simultaneously without interference.

Several variants of DSL technology are available. Residential Internet customers use a specific form known as Asymmetric Digital Subscriber Line (ADSL). The asym- metry arises because most users tend to receive more data than they send, and ADSL meets the need because ADSL is designed to transfer more from the ISP to the custo- mer than from the customer to the ISP. In fact, the ADSL variant has become so dom- inant that phone companies have stopped advertising ADSL service, and simply use the term DSL.

11.7 Cable Modem Access

Before the Internet became popular, the cable television industry already had wir- ing in place to most homes. The coaxial cable the industry used was originally designed to deliver analog video signals, and the hardware was only designed to send information in one direction (from the cable company to the subscriber). Researchers devised a modification of the cable infrastructure that made it possible to transfer Inter- net data over a cable that simultaneously sends video signals. Although the cable in- dustry has a technical name for the standards, the technology has become known to the public as cable modem access technology to emphasize that a user needs a special modem. Figure 11.3 illustrates the equipment used.

User’s TV

computer TV system

cable modem

cable carries both TV and data

User’s cable modem Splitter divides signals

into TV and data

Figure 11.3 Illustration of the equipment used with cable modem access.

Sec. 11.7 Cable Modem Access 125

At the subscriber’s site, a cable modem connects between the user’s computer and a cable TV outlet, using Ethernet for the connection between the modem and the com- puter. The cable company also has a cable modem at its end. The modem at the subscriber’s location communicates with the modem at the cable center by sending sig- nals over the coaxial cable that connects the locations. Analogous to DSL modems, ca- ble modems are designed so that data transmission does not interfere with television signals, making it possible to send data over the existing wiring at the same time as ca- ble television signals.

In terms of data transfer, cable modems can transfer more bits per second than even DSL. Initially, cable modem access offered rates of six or eight million bits per second. Now, major providers offer Gigabits per second (billions of bits per second).

11.8 Wireless Access Technologies

It may seem that DSL and cable modem technologies solve the last mile problem completely. However, each has limitations. DSL has a distance limitation that prevents the signals from traveling as far as conventional telephone signals. Thus, it cannot be used to provide service in rural areas. Furthermore, both DSL and cable modem tech- nologies can only be used where physical wires can be run. For example, communica- tion wires may not extend to a cabin in the woods, even if the cabin is only a short dis- tance from a town.

To provide Internet access to such locations, engineers have wireless access tech- nologies. Although all wireless networks use radio waves to carry data, a wide variety of technologies have been developed. Some are point to point, meaning that special an- tennas are used to aim the transmissions in a straight line between two communicating sites (e.g., between a remote residence and an ISP), and some use antennas that broad- cast in all directions (e.g., between a transmitter and a set of houses that are close by). Others use a satellite orbiting the earth to relay data between subscribers at arbitrary lo- cations and an ISP. The point is:

A variety of wireless access technologies has been developed to meet various needs.

We have already seen one technology that is used for Internet access: Wi-Fi. Re- call from Chapter 6 that Wi-Fi is classified as a Local Area Network because Wi-Fi can only reach computers in a small area around an access point (e.g., inside a house or in- side a store). Many organizations use Wi-Fi to provide Internet access to customers. For example, hotels, coffee shops, airports, and shopping malls often provide Wi-Fi ac- cess, as do high schools, universities, and hospitals.

To provide Wi-Fi Internet access, an owner needs two things; an Internet connec- tion and a Wi-Fi device. The Internet connection can use any of the technologies described above. For example, a national coffee shop chain uses a leased line to con-

K392894.indd 152 03/08/18 12:07 pmComer, Douglas E.. The Internet Book : Everything You Need to Know about Computer Networking and How the Internet Works, CRC Press LLC, 2018. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/apus/detail.action?docID=5502790. Created from apus on 2025-01-23 05:39:01.

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124 Internet Access Using Broadband And Wireless Chap. 11

As Figure 11.2 shows, only one set of wires connects a user with the telephone switching center. Technically, a DSL modem sends data using higher frequencies than a voice call. At the switching center, a small device known as a splitter separates the sig- nals so that voice signals can be sent to the voice telephone system and DSL signals can be sent to a DSL modem that connects to the Internet. At the user’s location, a splitter (also known as a DSL filter) prevents a user’s telephone from generating random signals that could interfere with DSL. The point is:

Although it uses the same wiring as a conventional landline telephone, DSL offers much higher data transfer rates than dial-up access. Furthermore, splitters allow conventional telephone calls and data transfer to proceed simultaneously without interference.

Several variants of DSL technology are available. Residential Internet customers use a specific form known as Asymmetric Digital Subscriber Line (ADSL). The asym- metry arises because most users tend to receive more data than they send, and ADSL meets the need because ADSL is designed to transfer more from the ISP to the custo- mer than from the customer to the ISP. In fact, the ADSL variant has become so dom- inant that phone companies have stopped advertising ADSL service, and simply use the term DSL.

11.7 Cable Modem Access

Before the Internet became popular, the cable television industry already had wir- ing in place to most homes. The coaxial cable the industry used was originally designed to deliver analog video signals, and the hardware was only designed to send information in one direction (from the cable company to the subscriber). Researchers devised a modification of the cable infrastructure that made it possible to transfer Inter- net data over a cable that simultaneously sends video signals. Although the cable in- dustry has a technical name for the standards, the technology has become known to the public as cable modem access technology to emphasize that a user needs a special modem. Figure 11.3 illustrates the equipment used.

User’s TV

computer TV system

cable modem

cable carries both TV and data

User’s cable modem Splitter divides signals

into TV and data

Figure 11.3 Illustration of the equipment used with cable modem access.

Sec. 11.7 Cable Modem Access 125

At the subscriber’s site, a cable modem connects between the user’s computer and a cable TV outlet, using Ethernet for the connection between the modem and the com- puter. The cable company also has a cable modem at its end. The modem at the subscriber’s location communicates with the modem at the cable center by sending sig- nals over the coaxial cable that connects the locations. Analogous to DSL modems, ca- ble modems are designed so that data transmission does not interfere with television signals, making it possible to send data over the existing wiring at the same time as ca- ble television signals.

In terms of data transfer, cable modems can transfer more bits per second than even DSL. Initially, cable modem access offered rates of six or eight million bits per second. Now, major providers offer Gigabits per second (billions of bits per second).

11.8 Wireless Access Technologies

It may seem that DSL and cable modem technologies solve the last mile problem completely. However, each has limitations. DSL has a distance limitation that prevents the signals from traveling as far as conventional telephone signals. Thus, it cannot be used to provide service in rural areas. Furthermore, both DSL and cable modem tech- nologies can only be used where physical wires can be run. For example, communica- tion wires may not extend to a cabin in the woods, even if the cabin is only a short dis- tance from a town.

To provide Internet access to such locations, engineers have wireless access tech- nologies. Although all wireless networks use radio waves to carry data, a wide variety of technologies have been developed. Some are point to point, meaning that special an- tennas are used to aim the transmissions in a straight line between two communicating sites (e.g., between a remote residence and an ISP), and some use antennas that broad- cast in all directions (e.g., between a transmitter and a set of houses that are close by). Others use a satellite orbiting the earth to relay data between subscribers at arbitrary lo- cations and an ISP. The point is:

A variety of wireless access technologies has been developed to meet various needs.

We have already seen one technology that is used for Internet access: Wi-Fi. Re- call from Chapter 6 that Wi-Fi is classified as a Local Area Network because Wi-Fi can only reach computers in a small area around an access point (e.g., inside a house or in- side a store). Many organizations use Wi-Fi to provide Internet access to customers. For example, hotels, coffee shops, airports, and shopping malls often provide Wi-Fi ac- cess, as do high schools, universities, and hospitals.

To provide Wi-Fi Internet access, an owner needs two things; an Internet connec- tion and a Wi-Fi device. The Internet connection can use any of the technologies described above. For example, a national coffee shop chain uses a leased line to con-

124 Internet Access Using Broadband And Wireless Chap. 11

As Figure 11.2 shows, only one set of wires connects a user with the telephone switching center. Technically, a DSL modem sends data using higher frequencies than a voice call. At the switching center, a small device known as a splitter separates the sig- nals so that voice signals can be sent to the voice telephone system and DSL signals can be sent to a DSL modem that connects to the Internet. At the user’s location, a splitter (also known as a DSL filter) prevents a user’s telephone from generating random signals that could interfere with DSL. The point is:

Although it uses the same wiring as a conventional landline telephone, DSL offers much higher data transfer rates than dial-up access. Furthermore, splitters allow conventional telephone calls and data transfer to proceed simultaneously without interference.

Several variants of DSL technology are available. Residential Internet customers use a specific form known as Asymmetric Digital Subscriber Line (ADSL). The asym- metry arises because most users tend to receive more data than they send, and ADSL meets the need because ADSL is designed to transfer more from the ISP to the custo- mer than from the customer to the ISP. In fact, the ADSL variant has become so dom- inant that phone companies have stopped advertising ADSL service, and simply use the term DSL.

11.7 Cable Modem Access

Before the Internet became popular, the cable television industry already had wir- ing in place to most homes. The coaxial cable the industry used was originally designed to deliver analog video signals, and the hardware was only designed to send information in one direction (from the cable company to the subscriber). Researchers devised a modification of the cable infrastructure that made it possible to transfer Inter- net data over a cable that simultaneously sends video signals. Although the cable in- dustry has a technical name for the standards, the technology has become known to the public as cable modem access technology to emphasize that a user needs a special modem. Figure 11.3 illustrates the equipment used.

User’s TV

computer TV system

cable modem

cable carries both TV and data

User’s cable modem Splitter divides signals

into TV and data

Figure 11.3 Illustration of the equipment used with cable modem access.

Sec. 11.7 Cable Modem Access 125

At the subscriber’s site, a cable modem connects between the user’s computer and a cable TV outlet, using Ethernet for the connection between the modem and the com- puter. The cable company also has a cable modem at its end. The modem at the subscriber’s location communicates with the modem at the cable center by sending sig- nals over the coaxial cable that connects the locations. Analogous to DSL modems, ca- ble modems are designed so that data transmission does not interfere with television signals, making it possible to send data over the existing wiring at the same time as ca- ble television signals.

In terms of data transfer, cable modems can transfer more bits per second than even DSL. Initially, cable modem access offered rates of six or eight million bits per second. Now, major providers offer Gigabits per second (billions of bits per second).

11.8 Wireless Access Technologies

It may seem that DSL and cable modem technologies solve the last mile problem completely. However, each has limitations. DSL has a distance limitation that prevents the signals from traveling as far as conventional telephone signals. Thus, it cannot be used to provide service in rural areas. Furthermore, both DSL and cable modem tech- nologies can only be used where physical wires can be run. For example, communica- tion wires may not extend to a cabin in the woods, even if the cabin is only a short dis- tance from a town.

To provide Internet access to such locations, engineers have wireless access tech- nologies. Although all wireless networks use radio waves to carry data, a wide variety of technologies have been developed. Some are point to point, meaning that special an- tennas are used to aim the transmissions in a straight line between two communicating sites (e.g., between a remote residence and an ISP), and some use antennas that broad- cast in all directions (e.g., between a transmitter and a set of houses that are close by). Others use a satellite orbiting the earth to relay data between subscribers at arbitrary lo- cations and an ISP. The point is:

A variety of wireless access technologies has been developed to meet various needs.

We have already seen one technology that is used for Internet access: Wi-Fi. Re- call from Chapter 6 that Wi-Fi is classified as a Local Area Network because Wi-Fi can only reach computers in a small area around an access point (e.g., inside a house or in- side a store). Many organizations use Wi-Fi to provide Internet access to customers. For example, hotels, coffee shops, airports, and shopping malls often provide Wi-Fi ac- cess, as do high schools, universities, and hospitals.

To provide Wi-Fi Internet access, an owner needs two things; an Internet connec- tion and a Wi-Fi device. The Internet connection can use any of the technologies described above. For example, a national coffee shop chain uses a leased line to con-

K392894.indd 153 03/08/18 12:07 pmComer, Douglas E.. The Internet Book : Everything You Need to Know about Computer Networking and How the Internet Works, CRC Press LLC, 2018. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/apus/detail.action?docID=5502790. Created from apus on 2025-01-23 05:39:01.

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126 Internet Access Using Broadband And Wireless Chap. 11

nect each coffee shop to the Internet; other small retail stores obtain cable modem ser- vice from a local ISP. Once Internet access is in place, only one additional piece of equipment is needed to offer Wi-Fi service to others. The device is known as a wireless access point. Vendors who sell such devices to consumers prefer the name wireless router; the terminology is appropriate because the device connects the Ethernet network on the modem to the Wi-Fi network, and forwards packets between the two. In essence, the device performs the same function as other Internet routers. Figure 11.4 il- lustrates the equipment needed to provide Wi-Fi access.

modem wireless router

Internet connection to

an ISP

Ethernet used

Wi-Fi used

Figure 11.4 Illustration of the equipment used to provide Wi-Fi access.

In the figure, the modem can be a leased line modem, DSL modem, cellular modem, or cable modem, depending on the technology the user selects for their Internet service. The connection between the modem and wireless router typically uses an Eth- ernet cable, which is the same cable used to connect a modem to a computer. The con- nection between the wireless router and the user’s devices uses the standard Wi-Fi para- digm — the wireless router must be configured to have an SSID, and devices must use the same SSID. In Chapter 17, we will learn that from the ISP’s perspective, a wireless router acts like a computer; the ISP does not know it is a router or that the router is us- ing Wi-Fi to provide Internet service to devices.

11.9 Cellular Wireless Access (4G and 5G)

Although it works well inside a coffee shop or a home, Wi-Fi cannot cross a large geographic distance because the technology has limited range. One approach to longer-distance wireless access uses the cellular phone system standards for 4th- Generation or 5th-Generation wireless technology (4G or 5G wireless). To understand cellular access networks, it is necessary to know that the cellular system is no longer limited to transmission of voice phone calls. Instead, Internet communication is now an integral part of the 4G and 5G systems. Thus, when a user who subscribes to a 4G ser- vice powers on a smart phone, the phone contacts a cell tower and is given the ability to transfer packets across the Internet.

Sec. 11.9 Cellular Wireless Access (4G and 5G) 127

As described above, the cellular system provides Internet access to each individual smart phone. However, using cellular as an Internet access technology also means us- ing a cellular connection to provide access to conventional computers, such as desktops and laptops. That is, cellular access replaces DSL or cable modem access.

To use the cellular system to provide Internet access, one merely uses a cellular modem instead of a DSL or cable modem. Two versions are available:

Mobile broadband modem Fixed cellular modem

11.9.1 Mobile Cellular Modems (4G or 5G)

A mobile broadband modem, which is available with both 4G and 5G, consists of a small device that is designed to be easy to carry when traveling. For example modems exist that are less than four inches long and a couple of inches wide, small enough to carry in one’s pocket. Mobile modems can be battery-powered, which permits their use without requiring a power cord.

A cellular modem contains two basic circuits: one that acts like a cell phone, and one that connects to a device. When powered on, the circuit that acts like a cell phone contacts the nearest cell tower. Assuming the provider recognizes the modem (i.e., the subscriber has signed up for service and the account is in good standing), the cell tower responds and agrees to forward Internet traffic.

The second circuit in a cellular modem provides connections to one or more de- vices. Most cellular modems use Wi-Fi for device connections. Thus, from the user’s point of view, a cellular modem acts like a wireless router. Some vendors advertise their cellular modem as a “portable Wi-Fi hotspot.” Figure 11.5 illustrates how a cellu- lar modem provides Internet access to a set of laptops.

cellular modem

cell tower

Wi-Fi used 4G or 5G cellular used

Figure 11.5 Illustration of a portable cellular modem (portable Wi-Fi hotspot) that uses Wi-Fi to connect devices to the Internet.

K392894.indd 154 03/08/18 12:07 pmComer, Douglas E.. The Internet Book : Everything You Need to Know about Computer Networking and How the Internet Works, CRC Press LLC, 2018. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/apus/detail.action?docID=5502790. Created from apus on 2025-01-23 05:39:01.

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126 Internet Access Using Broadband And Wireless Chap. 11

nect each coffee shop to the Internet; other small retail stores obtain cable modem ser- vice from a local ISP. Once Internet access is in place, only one additional piece of equipment is needed to offer Wi-Fi service to others. The device is known as a wireless access point. Vendors who sell such devices to consumers prefer the name wireless router; the terminology is appropriate because the device connects the Ethernet network on the modem to the Wi-Fi network, and forwards packets between the two. In essence, the device performs the same function as other Internet routers. Figure 11.4 il- lustrates the equipment needed to provide Wi-Fi access.

modem wireless router

Internet connection to

an ISP

Ethernet used

Wi-Fi used

Figure 11.4 Illustration of the equipment used to provide Wi-Fi access.

In the figure, the modem can be a leased line modem, DSL modem, cellular modem, or cable modem, depending on the technology the user selects for their Internet service. The connection between the modem and wireless router typically uses an Eth- ernet cable, which is the same cable used to connect a modem to a computer. The con- nection between the wireless router and the user’s devices uses the standard Wi-Fi para- digm — the wireless router must be configured to have an SSID, and devices must use the same SSID. In Chapter 17, we will learn that from the ISP’s perspective, a wireless router acts like a computer; the ISP does not know it is a router or that the router is us- ing Wi-Fi to provide Internet service to devices.

11.9 Cellular Wireless Access (4G and 5G)

Although it works well inside a coffee shop or a home, Wi-Fi cannot cross a large geographic distance because the technology has limited range. One approach to longer-distance wireless access uses the cellular phone system standards for 4th- Generation or 5th-Generation wireless technology (4G or 5G wireless). To understand cellular access networks, it is necessary to know that the cellular system is no longer limited to transmission of voice phone calls. Instead, Internet communication is now an integral part of the 4G and 5G systems. Thus, when a user who subscribes to a 4G ser- vice powers on a smart phone, the phone contacts a cell tower and is given the ability to transfer packets across the Internet.

Sec. 11.9 Cellular Wireless Access (4G and 5G) 127

As described above, the cellular system provides Internet access to each individual smart phone. However, using cellular as an Internet access technology also means us- ing a cellular connection to provide access to conventional computers, such as desktops and laptops. That is, cellular access replaces DSL or cable modem access.

To use the cellular system to provide Internet access, one merely uses a cellular modem instead of a DSL or cable modem. Two versions are available:

Mobile broadband modem Fixed cellular modem

11.9.1 Mobile Cellular Modems (4G or 5G)

A mobile broadband modem, which is available with both 4G and 5G, consists of a small device that is designed to be easy to carry when traveling. For example modems exist that are less than four inches long and a couple of inches wide, small enough to carry in one’s pocket. Mobile modems can be battery-powered, which permits their use without requiring a power cord.

A cellular modem contains two basic circuits: one that acts like a cell phone, and one that connects to a device. When powered on, the circuit that acts like a cell phone contacts the nearest cell tower. Assuming the provider recognizes the modem (i.e., the subscriber has signed up for service and the account is in good standing), the cell tower responds and agrees to forward Internet traffic.

The second circuit in a cellular modem provides connections to one or more de- vices. Most cellular modems use Wi-Fi for device connections. Thus, from the user’s point of view, a cellular modem acts like a wireless router. Some vendors advertise their cellular modem as a “portable Wi-Fi hotspot.” Figure 11.5 illustrates how a cellu- lar modem provides Internet access to a set of laptops.

cellular modem

cell tower

Wi-Fi used 4G or 5G cellular used

Figure 11.5 Illustration of a portable cellular modem (portable Wi-Fi hotspot) that uses Wi-Fi to connect devices to the Internet.

126 Internet Access Using Broadband And Wireless Chap. 11

nect each coffee shop to the Internet; other small retail stores obtain cable modem ser- vice from a local ISP. Once Internet access is in place, only one additional piece of equipment is needed to offer Wi-Fi service to others. The device is known as a wireless access point. Vendors who sell such devices to consumers prefer the name wireless router; the terminology is appropriate because the device connects the Ethernet network on the modem to the Wi-Fi network, and forwards packets between the two. In essence, the device performs the same function as other Internet routers. Figure 11.4 il- lustrates the equipment needed to provide Wi-Fi access.

modem wireless router

Internet connection to

an ISP

Ethernet used

Wi-Fi used

Figure 11.4 Illustration of the equipment used to provide Wi-Fi access.

In the figure, the modem can be a leased line modem, DSL modem, cellular modem, or cable modem, depending on the technology the user selects for their Internet service. The connection between the modem and wireless router typically uses an Eth- ernet cable, which is the same cable used to connect a modem to a computer. The con- nection between the wireless router and the user’s devices uses the standard Wi-Fi para- digm — the wireless router must be configured to have an SSID, and devices must use the same SSID. In Chapter 17, we will learn that from the ISP’s perspective, a wireless router acts like a computer; the ISP does not know it is a router or that the router is us- ing Wi-Fi to provide Internet service to devices.

11.9 Cellular Wireless Access (4G and 5G)

Although it works well inside a coffee shop or a home, Wi-Fi cannot cross a large geographic distance because the technology has limited range. One approach to longer-distance wireless access uses the cellular phone system standards for 4th- Generation or 5th-Generation wireless technology (4G or 5G wireless). To understand cellular access networks, it is necessary to know that the cellular system is no longer limited to transmission of voice phone calls. Instead, Internet communication is now an integral part of the 4G and 5G systems. Thus, when a user who subscribes to a 4G ser- vice powers on a smart phone, the phone contacts a cell tower and is given the ability to transfer packets across the Internet.

Sec. 11.9 Cellular Wireless Access (4G and 5G) 127

As described above, the cellular system provides Internet access to each individual smart phone. However, using cellular as an Internet access technology also means us- ing a cellular connection to provide access to conventional computers, such as desktops and laptops. That is, cellular access replaces DSL or cable modem access.

To use the cellular system to provide Internet access, one merely uses a cellular modem instead of a DSL or cable modem. Two versions are available:

Mobile broadband modem Fixed cellular modem

11.9.1 Mobile Cellular Modems (4G or 5G)

A mobile broadband modem, which is available with both 4G and 5G, consists of a small device that is designed to be easy to carry when traveling. For example modems exist that are less than four inches long and a couple of inches wide, small enough to carry in one’s pocket. Mobile modems can be battery-powered, which permits their use without requiring a power cord.

A cellular modem contains two basic circuits: one that acts like a cell phone, and one that connects to a device. When powered on, the circuit that acts like a cell phone contacts the nearest cell tower. Assuming the provider recognizes the modem (i.e., the subscriber has signed up for service and the account is in good standing), the cell tower responds and agrees to forward Internet traffic.

The second circuit in a cellular modem provides connections to one or more de- vices. Most cellular modems use Wi-Fi for device connections. Thus, from the user’s point of view, a cellular modem acts like a wireless router. Some vendors advertise their cellular modem as a “portable Wi-Fi hotspot.” Figure 11.5 illustrates how a cellu- lar modem provides Internet access to a set of laptops.

cellular modem

cell tower

Wi-Fi used 4G or 5G cellular used

Figure 11.5 Illustration of a portable cellular modem (portable Wi-Fi hotspot) that uses Wi-Fi to connect devices to the Internet.

K392894.indd 155 03/08/18 12:07 pmComer, Douglas E.. The Internet Book : Everything You Need to Know about Computer Networking and How the Internet Works, CRC Press LLC, 2018. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/apus/detail.action?docID=5502790. Created from apus on 2025-01-23 05:39:01.

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128 Internet Access Using Broadband And Wireless Chap. 11

11.9.2 Fixed Cellular Modems

Recent cellular standards have introduced an additional type of cellular modem in- tended to be installed permanently. Known as a fixed cellular modem, the unit is some- what larger than the mobile versions, and requires a power cord. The motivation for fixed cellular modems is straightforward: they are intended to replace DSL and cable modems. That is, instead of carrying the modem when traveling, a user installs the modem in their residence, connects one or more devices, and uses the modem for all their Internet access.

In addition to providing Wi-Fi connections for devices, fixed cellular modems offer wired connections using Ethernet. Thus, a fixed cellular modem provides exactly the same connections as a DSL or cable modem. We can summarize:

A cellular modem connects to the 4G or 5G cellular service and uses the connection to provide wireless Internet access to computers. Port- able units can be carried while traveling. Recent cellular systems offer fixed cellular modems that can be installed in place of a DSL or cable modem.

11.10 Summary

An access technology provides a connection between a user and an ISP (the so- called “last mile”). Both wired and wireless technologies are available. Early ISPs of- fered dial-up access, a narrowband service. Newer technologies, such as DSL and cable modems, provide broadband service, which means they transfer data at a higher rate. A wireless router provides local wireless access using Wi-Fi.

Recent standards for the cellular phone system include Internet data transport. Consequently, a cellular modem can be used as an Internet access technology; both small, portable devices and larger fixed devices are available.

EXERCISES

11.1 Take a poll of friends and find out which access technologies they have used: dial-up, DSL, cable modem, mobile broadband, or other.

11.2 ISPs that offer DSL or cable modem service often allow a user to choose a self-install option to save money. If an ISP gave you a modem, what would you need to do to in- stall it?

11.3 Contact local ISPs to find out how much their service costs and how many bits per second they will transfer. (Compare their regular rates, ignoring introductory discounts.) Which type of service is the best financially?

11.4 Suppose you have a choice between wired and wireless Internet services (i.e., DSL or cable modem vs. cellular). What advantages does wireless offer, if any?

Chapter Contents 12 Internet Performance 12.1 Introduction 131 12.2 Network Speed 131 12.3 What Does Speed Mean? 132 12.4 Brick Delivery 132 12.5 Transfers Across The Internet 134 12.6 Connecting Heterogeneous Networks 135 12.7 The Effect Of Sharing 137 12.8 Delays In The Internet 139 12.9 Should You Pay for Higher Speed Internet? 140 12.10 Summary 141

K392894.indd 156 03/08/18 12:07 pmComer, Douglas E.. The Internet Book : Everything You Need to Know about Computer Networking and How the Internet Works, CRC Press LLC, 2018. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/apus/detail.action?docID=5502790. Created from apus on 2025-01-23 05:39:01.

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128 Internet Access Using Broadband And Wireless Chap. 11

11.9.2 Fixed Cellular Modems

Recent cellular standards have introduced an additional type of cellular modem in- tended to be installed permanently. Known as a fixed cellular modem, the unit is some- what larger than the mobile versions, and requires a power cord. The motivation for fixed cellular modems is straightforward: they are intended to replace DSL and cable modems. That is, instead of carrying the modem when traveling, a user installs the modem in their residence, connects one or more devices, and uses the modem for all their Internet access.

In addition to providing Wi-Fi connections for devices, fixed cellular modems offer wired connections using Ethernet. Thus, a fixed cellular modem provides exactly the same connections as a DSL or cable modem. We can summarize:

A cellular modem connects to the 4G or 5G cellular service and uses the connection to provide wireless Internet access to computers. Port- able units can be carried while traveling. Recent cellular systems offer fixed cellular modems that can be installed in place of a DSL or cable modem.

11.10 Summary

An access technology provides a connection between a user and an ISP (the so- called “last mile”). Both wired and wireless technologies are available. Early ISPs of- fered dial-up access, a narrowband service. Newer technologies, such as DSL and cable modems, provide broadband service, which means they transfer data at a higher rate. A wireless router provides local wireless access using Wi-Fi.

Recent standards for the cellular phone system include Internet data transport. Consequently, a cellular modem can be used as an Internet access technology; both small, portable devices and larger fixed devices are available.

EXERCISES

11.1 Take a poll of friends and find out which access technologies they have used: dial-up, DSL, cable modem, mobile broadband, or other.

11.2 ISPs that offer DSL or cable modem service often allow a user to choose a self-install option to save money. If an ISP gave you a modem, what would you need to do to in- stall it?

11.3 Contact local ISPs to find out how much their service costs and how many bits per second they will transfer. (Compare their regular rates, ignoring introductory discounts.) Which type of service is the best financially?

11.4 Suppose you have a choice between wired and wireless Internet services (i.e., DSL or cable modem vs. cellular). What advantages does wireless offer, if any?

Chapter Contents 12 Internet Performance 12.1 Introduction 131 12.2 Network Speed 131 12.3 What Does Speed Mean? 132 12.4 Brick Delivery 132 12.5 Transfers Across The Internet 134 12.6 Connecting Heterogeneous Networks 135 12.7 The Effect Of Sharing 137 12.8 Delays In The Internet 139 12.9 Should You Pay for Higher Speed Internet? 140 12.10 Summary 141

128 Internet Access Using Broadband And Wireless Chap. 11

11.9.2 Fixed Cellular Modems

Recent cellular standards have introduced an additional type of cellular modem in- tended to be installed permanently. Known as a fixed cellular modem, the unit is some- what larger than the mobile versions, and requires a power cord. The motivation for fixed cellular modems is straightforward: they are intended to replace DSL and cable modems. That is, instead of carrying the modem when traveling, a user installs the modem in their residence, connects one or more devices, and uses the modem for all their Internet access.

In addition to providing Wi-Fi connections for devices, fixed cellular modems offer wired connections using Ethernet. Thus, a fixed cellular modem provides exactly the same connections as a DSL or cable modem. We can summarize:

A cellular modem connects to the 4G or 5G cellular service and uses the connection to provide wireless Internet access to computers. Port- able units can be carried while traveling. Recent cellular systems offer fixed cellular modems that can be installed in place of a DSL or cable modem.

11.10 Summary

An access technology provides a connection between a user and an ISP (the so- called “last mile”). Both wired and wireless technologies are available. Early ISPs of- fered dial-up access, a narrowband service. Newer technologies, such as DSL and cable modems, provide broadband service, which means they transfer data at a higher rate. A wireless router provides local wireless access using Wi-Fi.

Recent standards for the cellular phone system include Internet data transport. Consequently, a cellular modem can be used as an Internet access technology; both small, portable devices and larger fixed devices are available.

EXERCISES

11.1 Take a poll of friends and find out which access technologies they have used: dial-up, DSL, cable modem, mobile broadband, or other.

11.2 ISPs that offer DSL or cable modem service often allow a user to choose a self-install option to save money. If an ISP gave you a modem, what would you need to do to in- stall it?

11.3 Contact local ISPs to find out how much their service costs and how many bits per second they will transfer. (Compare their regular rates, ignoring introductory discounts.) Which type of service is the best financially?

11.4 Suppose you have a choice between wired and wireless Internet services (i.e., DSL or cable modem vs. cellular). What advantages does wireless offer, if any?

Chapter Contents 12 Internet Performance 12.1 Introduction 131 12.2 Network Speed 131 12.3 What Does Speed Mean? 132 12.4 Brick Delivery 132 12.5 Transfers Across The Internet 134 12.6 Connecting Heterogeneous Networks 135 12.7 The Effect Of Sharing 137 12.8 Delays In The Internet 139 12.9 Should You Pay for Higher Speed Internet? 140 12.10 Summary 141

K392894.indd 157 03/08/18 12:07 pmComer, Douglas E.. The Internet Book : Everything You Need to Know about Computer Networking and How the Internet Works, CRC Press LLC, 2018. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/apus/detail.action?docID=5502790. Created from apus on 2025-01-23 05:39:01.

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12

Internet Performance

12.1 Introduction

Chapter 10 explains that the Internet is a network of networks, created by using routers to interconnect all the networks, and Chapter 11 explains access technologies that can be used to connect a computer to the Internet. This chapter uses the concepts from the two chapters to explain Internet performance. It explains why ISPs advertise speed, and answers fundamental questions users often raise about the speed of their In- ternet service.

12.2 Network Speed

When they advertise their services, ISPs often use the term network speed and claim that they are selling a high-speed network or a faster network. If we think of everyday life, higher speed means something moves along at a higher velocity. For ex- ample, a car traveling at a higher speed than another car moves down the highway faster than the other car. For computer networks, the term speed is misleading because pack- ets do not move faster — they always travel across wires, optical fibers, and through space at the same rate: the speed of light.† The point is:

An ISP cannot make packets travel across a network faster than they do because the ISP cannot change the laws of physics to send signals faster than the speed of light.

†To be scientifically accurate, we should say approximately at the speed of light, but only physicists care about the distinction.

131

K392894.indd 158 03/08/18 12:07 pmComer, Douglas E.. The Internet Book : Everything You Need to Know about Computer Networking and How the Internet Works, CRC Press LLC, 2018. ProQuest Ebook Central, http://ebookcentral.proquest.com/lib/apus/detail.action?docID=5502790. Created from apus on 2025-01-23 05:39:01.

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