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Remote Connectivity

(PSTN) Public Switched Telephone Network or (POTS) Plain old telephone systems

Dial Up services: Customer pays on a per use basis (Analog Modem 56Kbps)
Modem converts Analog to Digital signals using an RJ11 connector

Internal Modem connections (PCI, ISA, AMR, PCMCIA, or integrated to the motherboard)

External Modem connections (USB or RS232 Serial COM)

Noise line, drivers and Call waiting can create havoc with modem connectivity

external modem internal modem

Modem manufacturers Hayes, 3COM/US Robotics, Diamond, Zoom

AT modem commands (Most Modem supports PPP and SLIP Protocols)

AT ok
ATA answer
ATD dial
ATDT dial tone
ATH hang up
ATZ reset
Other Internet connectivity

DSL – Digital Subscriber Line is an Internet Access method that uses a standard phone line to provide high speed Internet access. (To get fast connection you must be close to the CO - central office)

Types of DSL – The most popular are the ADSL – Asymmetric most common and SDSL – Symmetric (business)

dsl DSL

Cable Modem – Coaxial broadband communication (Shared bandwidth)
Wireless Internet – Connecting to the Internet using wireless must subscribe to a Wireless Internet Service Provider

cable modem cable modem


Satellite – Uses satellite technology for Internet connection

satellite satellite

Packet vs. Circuit Switching Technology

Packet Switching – Technology that break messages into packets, each of which can take a different route through the network to the destination where packets are reassembled. So, in a packet-switched network, resources are not reserved and can take travel several routes through various routers


Circuit Switching – Technology that use a dedicated connection between receiver and sender when sending packets. Network resources are static before the start and until the end of data transfer, creating a logical circuit.

Switching Method Pros, Cons and Key Features

Packet Switching Packets can be routed around network congestion

Packet switching makes efficient use of bandwidth Packets can become lost while taking different routes to destination

Messages on packets contain information Packets can look for best path

There are 2 types of packet switching: datagram and virtual-circuit

Circuit Switching Offers dedicated transmission
Multiple devices have the capability to share bandwidth Dedicated channels can cause delays if it’s not available

The dedicated line between sending and receiving devices can have problems Offers the capability of storing messages temporarily to reduce network congestion

If you want to setup Internet connection in Windows follow the following steps:
Remote Access – Dial Up, Private Dial Up, VPN, Dedicated Connection

Start>Programs>Accessories>Communication>New Connection Wizard

WAN Technologies CHART

WAN Technology Speed Supported Media Switching method Characteristics

ISDN- Integrated Services Digital Network


BRI - Basic Rate Interface 2B+ D Channels 64-128Kbps (home)

PRI – Primary Rate Interface 1.5Mpbs (business) Copper/Fiber optic Circuit Switching or
Packet Switching BRI uses 2B+D channels, PRI uses 23+D channels
ISDN uses the public network and requires dial up access


T-1 and J-1 1.5Mbps

E-1 2.048Mbps

T-3 44.736Mbps

E-3 34.368Mbps

J-3 32Mbps

E (Europe) and J (Japan)

Copper/Fiber Optic

Circuit Switching

T-carrier is used to create point-to-point network connections for private networks which is a dedicated lease line

FDDI – Fiber Distributed Data Interface
100Mbps Fiber Optic Dual Ring
Uses a dual ring configuration for fault tolerance. Uses a token passing media access method.



Frame Relay 56Kbps up to 44.736Mbps
(Fractional T1 or T3)
Copper/Fiber Optic Packet Switching
A packet-switching technology use for connecting devices on a WAN Frame Relay networks in the U.S. support data transfer rates at T-1 (1.544 Mbps and T-3 (45 Mbps) speeds

frame relay Frame Relay

X. 25
56Kbps or 64Kbps
Copper/Fiber Optic Packet Switching
X.25 is an older technology that provides packet switching over standard phone lines

ATM – Asynchronous Transfer Mode
Fiber Optic Packet Switching
Asynchronous Transfer Mode is considered best choice for mixing voice, video and data ATM uses fixed cells that are 53 bytes long


SONET – Synchronous Optical Network

sonet sonet

Optical carriers

OC-1- 51.85Mbps
OC-3 - 155.52Mbps
OC-12 - 622Mbps
OC-24 - 1.2Gbps
OC-48 - 2.4Gbps
OC-192 - 9.9Gbps
OC-255 - 13.21Gbps
OC-768 – 39.82Gbps

Fiber Optic
Point to Point

SONET defines synchronous data transfer over optical cable.

The European and Asian equivalent of SONET is SDH (synchronous digital hierarchy)

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