Please Whitelist This Site?

I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)

If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.

If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK.

Thanks for your understanding!

Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide


NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The Book is Here... and Now On Sale!

Read offline with no ads or diagram watermarks!
The TCP/IP Guide

Custom Search







Table Of Contents  The TCP/IP Guide
 9  Networking Fundamentals
      9  Network Performance Issues and Concepts

Previous Topic/Section
Understanding Performance Measurement Units
Previous Page
Pages in Current Topic/Section
1
2
3
Next Page
Simplex, Full-Duplex and Half-Duplex Operation
Next Topic/Section

Theoretical and Real-World Throughput, and Factors Affecting Network Performance
(Page 2 of 3)

External Performance Limiters

There are external factors that limit the performance of a network. Important issues here include the ability of the hardware to process the data, and also any bandwidth limitations that exist in the chain of data transmission between two nodes. Hardware issues most often show up with very fast networking technologies. Consider a Gigabit (1000 Mbps) Ethernet connection between two regular PCs. In “theory”, this connection should allow the transmission of 1 gigabit of data every second. Well, even beyond the matter of overhead mentioned above, no regular PC is capable of pumping this much data per second if its life depended on it. Only high-end servers have this capacity—and even they would have problems sustaining this unless they were doing nothing else. An older PC's hard disk probably can't even stream data fast enough to keep a 100 Mbit/s Ethernet connection busy. Thus, upgrading a 100 Mbps Ethernet card in an older machine to Gigabit is not likely to help as much as you might expect.

Bandwidth limitations cause network throughput issues because the entire network can only run as fast as its slowest link. These bottlenecks create reduced performance. As a common example, suppose you have a cable modem connection to the Internet that is rated at 1 Mbps for downloads. It may be very fast most of the time, but if the Web site you are accessing is totally bogged down, or it is having connectivity problems itself, you are not going to download from that site at 1Mbps. In fact, probably not even close.

Finally, it’s also important to remember that there are many technologies that simply do not always operate at a constant fixed speed; they may change speeds based on physical network characteristics. A good example is an analog modem, which can vary greatly in performance depending on the quality of the line over which it operates.

Network Configuration Problems

The issues I mentioned above are usually ones that you cannot do anything about; they are just the nature of the networking beast. The third category of performance limiters, misconfiguration, is different. This refers to network slowdowns that occur because hardware or software have not been set up correctly. Poor cabling, misconfigured interface cards, or bad drivers can seriously reduce the performance of a network—by 90% or even more.

These problems can usually be corrected, but only if you are looking for them. Driver problems are particularly insidious because the natural tendency is for people to blame hardware when slowdowns occur. However, you cannot get the most of your hardware devices without proper software to run it. These issues are much more significant with “bleeding edge” hardware than with established products, incidentally.

Also included in this category of issues are problems that occur due to poor design. For example, putting 30 busy workstations on a shared 10 Mbit/s Ethernet segment is likely to result in poor performance—using a network switch would be much better, since this would create multiple, independent segments for higher performance. Another common mistake is not providing a “fatter pipe” (higher bandwidth connection) to servers in a client/server setup. These issues can be avoided or ameliorated by reconfiguring the network—or even better, designing it properly in the first place, right?


Previous Topic/Section
Understanding Performance Measurement Units
Previous Page
Pages in Current Topic/Section
1
2
3
Next Page
Simplex, Full-Duplex and Half-Duplex Operation
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $



Home - Table Of Contents - Contact Us

The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005

Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.