Florida International University

1
Florida International University

• CGS 3300
• Introduction to Information Systems

2
How does an email travel down the data lines?

• 56 Kbps V.90 modem
• DSL
• Cable modem
• ISDN
• T1/T3
• Wireless connection

3
Email travels by V.90 Modem
56 Kbps V.90 Modem
email
Telco C.O.
Source ISP
Destination ISP
4
Email travels by V.90 Modem
Modem converts analog
56 Kbps V.90 Modem
email
digital
digital
Telco C.O.
Enters wire in analog form
ADC at C.O. converts to digital
5
What is the speed of a 56Kbps V.90 Modem?
1. 56 Kbps?
56 Kbps V.90 Modem
2. 33.6 Kbps?
3. 53 Kbps?
Download speed lt 53Kbps
Upload speed lt 33.6 Kbps
http//computingcentral.msn.com/internet/speedtest
.asp
6
xDSL, ADSL, RADSL or G.lite
ALCATEL
DOWNLOAD lt 1.5 Mbps
UPLOAD lt 364Kbps
www.dslreports.com
7
Cable modem
Cable one way Download great Upload through
telephone and 56K modem Cable - two way new
equipment required Cable - two way satellite
transmission Cable with fiber optics transmission
8
ISDN Integrated Services Digital Network
ISDN BRI WALL JACK RJ45
ISDN MODEM
Telco C.O.
DSU/CSU
DSU/CSU Data Service Unit/Channel Service
Unit Converts one digital signal to another type
of digital signal
9
ISDN Integrated Services Digital Network

• 64 K bps B
• 64 Kbps B
• 32 Kbps D signaling

• Use both lines to get 128 Kbps both ways
• Use one line for voice and one line for data
• Use one line for fax and one line for data
• Use one line for voice and one line for fax

10
T1/T3 Network
What is a T1 or a T3?
A T1 consists of 24 digital lines
Of 64 Kbps transmission speed
24 x 64 Kbps 1.544 Mbps
11
Getting into details of a T1
The voice signal is sampled at 8,000 hz x 8 bits
64Kbps The smallest unit of channel combination
in the US is 24 channels 24 x 64 1,
536,000 Add One additional bit is inserted into
the stream for every 192 bits of transfer, to
establish synchronization and we have 1,536,000
divide by 8,000 192 Add 1 to 192 193 x 8,000
1.544 Mbps
12
2 way satellite
Unlike DirecPC, which needs a standard phone line
to send data to the Internet, StarBand is a
two-way service It sends and receives data
through the satellite antenna. StarBand doesnt
require a phone line and is always connected to
the Internet.
The StarBand service is available from two
sources RadioShack and EchoStar Communications
dish Network dealers. If you go through
RadioShack, youll have to purchase a complete PC
along with the antenna. The software and two PCI
cards are preinstalled in the PC, and the 24- by
36-inch elliptical antenna has to be
professionally installed, since alignment is
critical to system performance. Cost varies
depending on what PC you choose, but figure on
spending at least 900. Monthly service costs
59.95, with a one-year commitment. When you
order the service through StarBand, you are
provided with MSN as your ISP and supplied with
an MSN Hotmail account.
13
Who shares bandwidth?
YES
NO

• Cable
• Wireless
• T1
• T3

• 56K V.90 Modem
• xDSL
• ISDN