why Increasing Demands of Modern Applications

A perfect example of the increasing demands put on networks by applications is a law firm
that 10 years ago was running typical office-automation software applications on its LAN. The
average document worked on was about four pages in length and 12KB in size. This firm also
used electronic mail; a typical e–mail size was no more than 500 bytes. Other applications
included dBase III and a couple small corresponding databases, a terminal-emulation application
that connected to the firm’s IBM minicomputer, and a few Lotus 1-2-3 programs. The
size of transferred data files was relatively small, and the average 10Base-T network-segment
size was about 100 nodes per segment.
Today, the same law firm is still using its 10Base-T and finding it increasingly insufficient for
their ever-growing data processing and office-automation needs. The average document
length is still around four pages but, thanks to the increasing complexity of modern wordprocessing
software and templates, the average document is nearly 50KB in size!
Even simple e–mail messages have grown in size and complexity. An average simple e–mail
message size is now about 1.5KB, and, with the new message technologies that allow the
integration of inbound/outbound faxing, an e–mail message with a six-page fax attached has
an average size of 550KB. Further, the firm integrated the voice mail system with the e–mail
system so that inbound voice mail is automatically routed to the user’s mailbox. The average
30-second voice mail message is about 150KB.
The firm also implemented an imaging system that scans and stores many documents that
previously would have taken up physical file space. Included in this imaging system are litigation
support documents, accounting information, and older client documentation. A singlepage
TIF file can vary in size (depending on the complexity of the image) from 40 to 125KB.
Additional software applications include a client/server document-management system, a client/
server accounting system, and several other networked programs that the firm only
dreamed about 10 years before. Most of the firm’s attorneys make heavy use of the Internet,
often visiting sites that provide streaming audio and video.
Today, the firm’s average switched segment size is less than 36 nodes per segment, and
the segments are switched to a 100Mbps backbone. Even with these small segment sizes,
many segments are congested. Although the firm would like to begin running 100Base-TX
Ethernet to the desktop, it is finding that its Category 3 cabling does not support 100Base-
TX networking.
When this firm installs its new cabling system to support the next-generation network applications,
you can be sure that it will want to choose the cabling infrastructure and network application
carefully to ensure that its needs for the next 10 to 15 years will be accommodated.