Types Of Internet Connections

Connection Types

• Dial-up Access
• ISDN(Integrated Services Digital Network)
• Leased Lines
• Cable Internet

Dial-up Access

• Also known as narrowband
• Least expensive way to get connected with Internet
• Speed is too low.
• Use the Point-to-Point Protocol.
• To use a Dial-up You need a modem.
• Doesn't require any special H/W.
• Only used for Email & light Web Browsing.

#To establish a dial-up connection to the Internet ,following things are needed:

• An account with an Internet Access Provider(VSNL).
• A telephone connection
• A computer with serial port(for external modems)
• A modem(Internal /External)
• A communication software(Browser)

ISDN(Integrated Services Digital Network)

• Carries a variety of user traffic, such as digital video, data, and telephone network services, using the normal phone circuit-switched network
• Offers much faster call setup than modems by using out-of-band signaling (D channel)
• Often less than one second
• Provides a faster data transfer rate than modems by using the 64-kbps bearer channel (B channel).
• Highly Reliable
• Very Fast
• High Cost
• ISDN is all digital

Integrated Service

• Voice
• Video
• Image
• Data
• Media

Digital

• Signaling
• Switching
• Channels

Network

• World wide
• Inter Operating Communication

Components Of ISDN

• ISDN Channels
• ISDN Access Types
• ISDN Devices
• ISDN Interfaces

ISDN Channels
Three types of channels are there:

• B Channels
• D Channels
• H Channels

B Channels

1. 64 kbps unit
2.No restrictions

D Channels

1.Signaling Channel
2.X.25 Protocol
3.BRA-16 kbps
4.PRA-64 kbps

H Channels

1.High speed
2.H0-384 kbps
3.H11-1.536 Mbps
4.H12-entire European PRA

Access Types
There are two types:

• BRA(Basic Rates Access)
• PRA(Primary Rates Access)

BRA(BASIC RATES ACCESS)

• Provide service to individual user or small business.
• Access provides two 64 kbps B channel and one 16 kbps D Channel
• i.e. 2B + D = 144 kbps
• 1 B=>voice conversation
• 1 B=>Medium speed data session
• 1 D=>Signaling exchange
• Uses an additional 48 kbps of bandwidth for maintenance and synchronization.
• Total line capacity -i.e. 2B + D + 48 = 192 kbps

PRA(PRIMARY RATES ACCESS)

• Based on pre-ISDN digital carrier Technology
• High capacity service to large customers
• Two kinds of PRA
• 23B + D
• 30B + D
• In North America & Japan 23B +D PRA operates at 1.544 Mbps.
• Rest of the world 30B + D PRA ,operates at upto 2.048 Mbps.

ISDN Devices

• It is not actually a hardware but it is a standard collection of functions that usually performed by the hardware units.
• Devices are:
• Terminal Equipment (TE)
• TE is a piece of communicating equipment that compiles with the ISDN standards.
• Terminal Adapter (TA)
• TA is a special interface conversion device that allows communication of devices that don’t confirm to ISDN standards to communicate over ISDN.

• Network Termination 1 (NT1)
• performs the logical interface function of switching & local device control(local signaling).
• Network Termination 2 (NT2)
•  performs physical interface conversion between dissimilar customer & n/w sides of the interface.
• Exchange Termination (ET)
• same as NT but it separates the B channels and terminates signaling path of the customer’s D channel

ISDN Interface

• Standard Reference Point not a physical interface
• There are 4 distinct interface in the customer’s connections to network R, S, T and U.
• R- reference point between non-ISDN equipments & TA.
• S- reference point between terminals(TE/TA) & NT.
• T- reference point between NT1 and NT2.
• U- reference point between NT1(NT2) and ISDN carrier’s local transmission loop.

Leased Line (Dedicated Lines)

• It is a telephone line that has been leased for private use.
• Contrasted with a switched line.
• It does not have a telephone number ,each side of the line being permanently connected to the others.
• The speed available are in the range of 9.6 kbps to 2 mbps.
• The efficiency of the leased line connection is 2-2.5 times better than the dial-up access.
• Cost is more than the dial-up access.

Cable Internet

• Cable TV companies also provide Internet services.
• High bandwidth internet service for homes or small offices.
• Accessed over the same line as the cable TV.
• Although, the cable and TV signal are transmitted on the same media ,no interference with two different signals.
• Cable TV lines are coax cables.
• Cable internet is continuous connection.
• Cable modem is needed & there is no need for username & password to connect.

Advantages of cable internet

• High connection speed
• Convenient (suitable)
• Does not affect your phone line.
• Connection speed is not affected by the distance from ISP operation center
• Easy setup with self installation kit

Disadvanteges of cable internet

• Expensive than Dial up
• Higher Security risk than Dial up
• Bandwidth is shared over the same cable line.
• Upload speed is slower than download speed