Internet connectivity mechanisms

Internet connectivity mechanisms

Now anybody can access the Internet and get it's benefit. There are several ways to connect to the Internet.

Dial-UP

ISDN

DSL

Cable connections

Wireless connections

T-1, T-2 and T-3 lines

Satellite

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Dial-UP

• Dialup is simply the application of the Public Switched Telephone Network (PSTN) to carry data on behalf of the end user. It involves a customer premises equipment (CPE) device sending the telephone switch a phone number to direct a connection to.

• Speed ranges from 2400 bps to 56 Kbps

• Twisted pair (regular phone lines) is the physical medium.

• Cheap but slow compared with other technologies.

• Speed may degrade due to the amount of line noise

ISDN

• Integrated Services Digital Network is a telephone system network. ISDN is integrates speech and data on the same lines, adding features that were not available in the classic telephone system. access interfaces

  • Basic Rate Interface (BRI)

  • Primary Rate Interface (PRI)

  • Broadband-ISDN (B-ISDN)

• Dedicated telephone line and router required.

• Speed ranges from 64 Kbps to 128 Kbps.

• Physical medium is Twisted pair.

• Not available everywhere but becoming more widespread.

• An ISDN line costs slightly more than a regular telephone line, but you get 2 phone lines from it.

• 56K ISDN is much faster than a 56K dialup line

Digital subscriber line ( DSL )

• Digital subscriber line ( DSL ) is more expensive than dialup, but provides a faster connection. DSL also uses telephone lines, but unlike dialup access, DSL provides a continuous connection to the Internet.

• This connection option uses a special high-speed modem that separates the DSL signal from the telephone signal and provides an Ethernet connection to a host computer or LAN.

• Doesn’t interfere with normal telephone use.

• Bandwidth is dedicated, not shared as with cable.

• Bandwidth is affected by the distance from the network hubs. Must be within 5 km (3.1 miles) of telephone company switch.

• Limited availability.

• Not networkable

Cable Internet

• A cable Internet is a connection option offered by cable television service providers. The Internet signal is carried on the same coaxial cable that delivers cable television to homes and businesses.

• A special cable modem separates the Internet signal from the other signals carried on the cable and provides an Ethernet connection to a host computer or LAN.

• CMTS is the equipments provides the Cable Internet service to the users. It provides the same service which DSLAM offers.

• 512 Kbps to 20 Mbps

• Coaxial cable and in some cases telephone lines used for upstream requests as physical medium

Wireless

• Access is gained by connection to a high speed cellular like local multi-point communications system (LMCS) network via wireless transmitter/receiver.

• Speed is 30 Mbps or more

• Physical medium is Airwaves (antenna)

• Can be used for high speed data, broadcast TV and wireless telephone service.

Satellite

• Satellite connection is an option offered by satellite service providers.

• The user's computer connects through Ethernet to a satellite modem that transmits radio signals to the nearest Point of Presence, or POP, within the satellite network.

• Newer versions have two-way satellite access, removing need for phone line.

• In older versions, the computer sends request for information to an ISP via normal phone dial-up communications and data is returned via high speed satellite to rooftop dish, which relays it to the computer via a decoder box.

• Speed is 30 Mbps or more

• Physical medium is Airwaves (antenna)

• Bandwidth is not shared.

• Satellite companies are set to join the fray soon which could lead to integrated TV and Internet service using the same equipment and WebTV like integrated services

• Latency is typically high

• Some connections require an existing Internet service account.

Frame Relay

• Provides a type of "party line" connection to the Internet.

• Requires a FRAD (Frame Relay Access Device) similar to a modem, or a DSU/CSU.

• speed ranges from 56 Kbps to 1.544 Mbps (or more, depending on connection type)

• Various physical mediums used

• May cost less than ISDN in some locations.

• Limited availability.

• Uses one of the connection types below, fractional up to OC3

Fractional T1 (Flexible DS1)

• Only a portion of the 23 channels available in a T1 line is actually used.

• Speed ranges from 64 Kbps to 1.544 Mbps

• Physical medium is Twisted-pair or coaxial cable

• Cheaper than a full T1 line with growth options of 56 Kbps or 64 Kbps increments as required.

T1

• Special lines and equipment (DSU/CSU and router) required.

• Speed 1.544 Mbps

• Physical medium is Twisted-pair, coaxial cable, or optical fiber

• Typically used for high bandwidth demands such as videoconferencing and heavy graphic file transfers.

• Minimum for large businesses and ISPs.

• Expensive

T3

• Typically used for ISP to Internet infrastructure.

• Speed 44.736 Mbps

• Physical medium is Optical fiber

OC-1

• Typically used for ISP to Internet infrastructure within Internet infrastructure.

• Speed 51.84 Mbps

• Physical medium is Optical fiber

OC-3

• Typically used for large company backbone or Internet backbone.

• Speed 155.52 Mbps

• Physical medium is Optical fiber