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!

Get The TCP/IP Guide for your own computer.
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
Performance Measurements: Speed, Bandwidth, Throughput and Latency
Previous Page
Pages in Current Topic/Section
1
23
Next Page
Theoretical and Real-World Throughput, and Factors Affecting Network Performance
Next Topic/Section

Understanding Performance Measurement Units
(Page 1 of 3)

People who make networking hardware, or write materials that try to tell you how to operate it, make use of many terms to describe performance, such as throughput and bandwidth. In addition, they also use several different units to measure performance. Unfortunately—and I'm sure you knew this was coming—these units are often used incorrectly, and they are also very similar to each other in name. Worse, they also have overlapping abbreviations, and lots of people use these abbreviations without making clear what the heck they are talking about. Isn't that great?

“Bits and Bytes”

The first issue is “the infamous letter B”. Or rather, I should say, the matter of the “big B” and the “little b”.By popular convention, the capitalized “B” is supposed to be used for “byte”, and the lower-case “b” for bit—this is the way these abbreviations are always used in this Guide. (A byte is normally eight bits; sometimes the term octet is used instead. If you aren’t familiar with these terms, refer to the primer on binary basics, where you will also find a discussion of the small “controversy” related to bytes and octets.)

Unfortunately, this convention is not followed strictly by everyone. As a result, you may on occasion see “b” being used to refer to bytes, and “B” used for bits. This “b” and “B” business causes a tremendous amount of confusion sometimes, with people mistaking bits for bytes and accidentally thinking that networks are running eight times faster or slower than they really are.

Bear in mind when looking at speed ratings that they are almost always given in terms of bits, not bytes. The “56k” in a “56k modem” means 56,000 bits, not 56,000 bytes, of theoretical transfer speed. (This is true even if someone calls it a “56K” modem.) Similarly, Fast Ethernet operates at 100 megabits per second, not megabytes, and a 1.544 Mbps T-1 link sends a theoretical maximum of 1,544,000 bits each second. This, at least, is usually pretty consistent.

When it comes to throughput measurements, however, both bits and bytes are used, so you have to be careful. Raw throughput values are normally given in bits per second, but many software applications report transfer rates in bytes per second, including many Web browsers and FTP client programs. This often leads to users wondering why they are only getting one eighth of their expected download or transfer speeds.

Key Concept: In most cases in discussions of networking performance, the lower-case letter “b” refers to “bits” and the upper-case “B” to “bytes”. However, these conventions are not always universally followed, so context must be used to interpret a particular measurement.



Previous Topic/Section
Performance Measurements: Speed, Bandwidth, Throughput and Latency
Previous Page
Pages in Current Topic/Section
1
23
Next Page
Theoretical and Real-World Throughput, and Factors Affecting Network Performance
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.