Information Technology Reference
In-Depth Information
category of the installation, and you should get a printed report. Keep in mind that
you will have to pay extra to have each link scanned. The equipment to perform the
testing is expensive and the installer will expect to be compensated.
The Need for Speed
“Why do I need higher network speeds?” you might ask. The answer lies in under-
standing the increasing size of data transfers in the modern network. The common
word processing tasks have modest file transfer requirements, even if files are main-
tained on a server. However, we are doing many more tasks than letter writing
today, and these new applications have placed great demands on our network trans-
fer rates.
For example, the average user today accesses graphics-rich Internet Web sites,
often with audio and video multimedia content. We routinely attach fairly large
documents, such as Word™ documents and PowerPoint™ files in our e-mails.
Businesses are increasingly putting voice traffic onto digital networks. And appli-
cations such as video teleconferencing, and telemedicine have high constant-band-
width requirements. In fact, digitized X-rays and CT scans are routinely being
transmitted over the networks of medical providers. Many cities now offer real-
time video of roadway traffic, and broadcast television and entertainment perform-
ances are close behind.
How much bandwidth is needed for efficient networking? That depends on the
application and the perception of the user. The chart in Table 4.2 shows some com-
parative applications and the amount of bandwidth each would need to complete its
transmission in 1 minute.
Now imagine staring at your computer monitor for 60 seconds while you are
waiting for this application to load. It seems a lot longer than you would normally
tolerate, at least without some choice words under your breath.
TABLE 4.2
Network Speed Required for File Transfers in 1 Minute
File Size
File Application
1-Minute Transfer Rate*
300 kB
Web page with graphics
40 Kbps
3 MB P
PowerPoint™ file
400 Kbps
30 MB
MP3™ audio—30 min.
4 Mbps
300 MB
DVD clip—9 min
40 Mbps
3 GB
Magazine—100 pages (MPEG-2)
400 Mbps
30 Gbytes
CT scan, three views
4 Gbps
*Since 1 byte
8 bits, 300 kB
8 bits/byte
2400 kb, and 2400 kb
60 seconds
40 Kbps (Kbps per second).
