Photo:1
Photo:2
Photo:3
Photo:4
Photo:1 Photo:2 Photo:3 Photo:4 |
| Example | |
| 2>
Imagine that a file is being transferred using HTTP over a switched Ethernet connection with a total channel capacity of 100 megabits per second. The file cannot be transferred over Ethernet as a single contiguous stream; instead, it must be broken down into individual chunks. These chunks must be no larger than the maximum transmission unit of Ethernet, which is 1500 bytes. Each packet requires 20 bytes of IP header information and 20 bytes of TCP header information, so only 1460 bytes are available per packet for the file transfer data itself (Unix systems, Linux, and Mac OS X are further limited to 1448 bytes as they also carry a 12 bytes time stamp[1]). Furthermore, the data are transmitted over Ethernet in a frame, which imposes a 26 byte overhead per packet. Given these overheads, the maximum goodput is 1460/1526 × 100 Mbit/s which is 95.67 megabits per second or 11.959 megabytes per second.
Note that this example doesn't consider some additional Ethernet overhead, such as the interframe gap (a minimum of 96 bit times), nor collisions (which have a variable impact, depending on the network load). TCP itself also adds the overhead of acknowledgements (which along with the round-trip delay time and the TCP window size in effect will rate-limit each individual TCP connection, see bandwidth-delay product). This example also does not consider the overhead of the HTTP protocol itself, which becomes relevant when transferring small files.
[edit] Tags:Bits,Channel Capacity,Http,Ethernet,Megabits Per Second,Maximum Transmission Unit,Bytes,Ip,Tcp,Unix,Linux,Mac Os X,Mbit/s,Megabytes Per Second,Interframe Gap,Round-trip Delay Time,Bandwidth-delay Product, | |
| Data delivery time | |
| 2>
The goodput is a ratio between delivered amount of information, and the total delivery time. This delivery time includes:
inter-packet time gaps caused by packet generation processing time (a source that does not use the full network capacity), or by protocol timing (for example collision avoidance)
data and overhead transmission delay (amount of data divided by bit rate)
propagation delay (distance divided by wave propagation speed),
packet queuing delay
intermediate node store-and-forward processing delay,
packet retransmission time (in case of deleted packets in congested routers, or detected bit errors),
delayed acknowledge due to flow control, congestion avoidance and processing delay.
[edit] Tags:Flow Control,Collision Avoidance,Transmission Delay,Bit Rate,Propagation Delay,Queuing Delay,Store-and-forward Processing Delay,Congestion Avoidance,Processing Delay, | |
| References | |
| 2>
^ Stuart Cheshire. "TCP Performance problems caused by interaction between Nagle's Algorithm and Delayed ACK". http://www.stuartcheshire.org/papers/NagleDelayedAck/index.html. Retrieved 2010-01-13.
[edit] Tags: | |
| See also | |
| 2>
Bandwidth (computing)
Throughput
Measuring network throughput
Link and system spectral efficiency
[edit] Tags:Throughput, | |
| References | |
| 2>
Goodput calculation
An Empirical Characterization of Instantaneous Throughput in 802.11b WLANs
Energy-Efficient Power and Rate Control with QoS Constraints: A Game-Theoretic Approach
RFC 2647 — Benchmarking Terminology for Firewall Performance
This computer networking article is a stub. You can help Wikipedia by expanding it.
v
d
e
Retrieved from "http://en.wikipedia.org/w/index.php?title=Goodput&oldid=461323489"
Categories: Computer network stubsNetwork performance
Personal tools
Log in / create account
Namespaces
Article
Talk
Variants
Views
Read
Edit
View history
Actions
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact Wikipedia
Toolbox
What links here
Related changes
Upload file
Special pages
Permanent link
Cite this page
Print/export
Create a bookDownload as PDFPrintable version
Languages
Deutsch
Italiano
This page was last modified on 18 November 2011 at 19:58.
Text is available under the Creative Commons Attribution-ShareAlike License;
additional terms may apply.
See Terms of use for details.
Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.Contact us
Privacy policy
About Wikipedia
Disclaimers
Mobile view
if ( window.isMSIE55 ) fixalpha();
if ( window.mediaWiki ) {
mw.loader.load(["mediawiki.user", "mediawiki.util", "mediawiki.page.ready", "mediawiki.legacy.wikibits", "mediawiki.legacy.ajax", "mediawiki.legacy.mwsuggest", "ext.gadget.wmfFR2011Style", "ext.vector.collapsibleNav", "ext.vector.collapsibleTabs", "ext.vector.editWarning", "ext.vector.simpleSearch", "ext.UserBuckets", "ext.articleFeedback.startup", "ext.articleFeedbackv5.startup", "ext.markAsHelpful"]);
}
if ( window.mediaWiki ) {
mw.user.options.set({"ccmeonemails":0,"cols":80,"date":"default","diffonly":0,"disablemail":0,"disablesuggest":0,"editfont":"default","editondblclick":0,"editsection":1,"editsectiononrightclick":0,"enotifminoredits":0,"enotifrevealaddr":0,"enotifusertalkpages":1,"enotifwatchlistpages":0,"extendwatchlist":0,"externaldiff":0,"externaleditor":0,"fancysig":0,"forceeditsummary":0,"gender":"unknown","hideminor":0,"hidepatrolled":0,"highlightbroken":1,"imagesize":2,"justify":0,"math":1,"minordefault":0,"newpageshidepatrolled":0,"nocache":0,"noconvertlink":0,"norollbackdiff":0,"numberheadings":0,"previewonfirst":0,"previewontop":1,"quickbar":5,"rcdays":7,"rclimit":50,"rememberpassword":0,"rows":25,"searchlimit":20,"showhiddencats":false,"showjumplinks":1,"shownumberswatching":1,"showtoc":1,"showtoolbar":1,"skin":"vector","stubthreshold":0,"thumbsize":4,"underline":2,"uselivepreview":0,"usenewrc":0,"watchcreations":1,"watchdefault":0,"watchdeletion":0,"watchlistdays":3,"watchlisthideanons":0,
"watchlisthidebots":0,"watchlisthideliu":0,"watchlisthideminor":0,"watchlisthideown":0,"watchlisthidepatrolled":0,"watchmoves":0,"wllimit":250,"flaggedrevssimpleui":1,"flaggedrevsstable":0,"flaggedrevseditdiffs":true,"flaggedrevsviewdiffs":false,"vector-simplesearch":1,"useeditwarning":1,"vector-collapsiblenav":1,"usebetatoolbar":1,"usebetatoolbar-cgd":1,"wikilove-enabled":1,"variant":"en","language":"en","searchNs0":true,"searchNs1":false,"searchNs2":false,"searchNs3":false,"searchNs4":false,"searchNs5":false,"searchNs6":false,"searchNs7":false,"searchNs8":false,"searchNs9":false,"searchNs10":false,"searchNs11":false,"searchNs12":false,"searchNs13":false,"searchNs14":false,"searchNs15":false,"searchNs100":false,"searchNs101":false,"searchNs108":false,"searchNs109":false,"gadget-wmfFR2011Style":1});;mw.user.tokens.set({"editToken":"+\\","watchToken":false});;mw.loader.state({"user.options":"ready","user.tokens":"ready"});
/* cache key: enwiki:resourceloader:filter:minify-js:4:b41a86ec4e0fe8329bc3ce917e792339 */
}
Tags: | |
z³ote monety view link view link view link view link view link |