Basics of network bandwidth, latency, and jitter
ฝัง
- เผยแพร่เมื่อ 28 ก.ย. 2010
- I'm certainly no Salman Khan of the Khan Academy, but I've been doing my little animated presentations for some time and Khan has giving me some inspiration to use TH-cam to keep trying the video form factor. I was asked to explain the concept of network latency to someone who found this article on Wall Street's speed wars fascinating using something other than geek talk, so I created this tutorial explaining what is bandwidth, latency, and jitter.
The following is a short 7 minute video I posted on TH-cam. As always, feedback and comments are welcome.
Sorry about three places towards the end where audio was recorded too loudly and clipped. The recording software didn't filter out the clipping and these are some of the minor issues I need to hammer out next time. Also note that the 123 miles per millisecond for the "speed of light" quoted is the speed of light in fiber optic cabling. Light travels significantly faster in air and space, around 186 miles per millisecond. And of course, my delivery is certainly not as smooth as Mr. Khan, but I'm hopeful that you'll find the information simple to understand.
One other interesting note is the TH-cam switches to a very low bitrate even for the 1080P version of this video which is fine because of the very static nature of the video. Normal 1080P gets 3.5 Mbps for the video stream but this clip uses less than a megabit per second. That's understandable because it's easy to compress with very little loss in quality. I would also note that the same thing is done for the Khan Academy videos. Now I've uploaded similarly static content before but they didn't get the low bandwidth treatment. I wonder if it's because of the all black background I use which is similar to Khan Academy videos. The bottom line is that it makes this video very bandwidth friendly and much more accessible to people with slower broadband connections. - วิทยาศาสตร์และเทคโนโลยี
R.I.P. headphone users. :/
The bandwidth you are talking about is actually Throughput. Bandwidth is a fixed maximum, like 10/100/1000 megabits/second. The throughput is what you can achieve in a real-life situation, but it is not necessarily affected by the latency, only if you are using TCP. If you use UDP there is no round trip, the data is just send without waiting for a answer, and so you can get more throughput.
Thanks Bro, you just Highlighted some important fundamentals...
01:06 a cat in the background wants to learn as well :)
Thanks a lot, man!
what a voice and speech wow
To some below
1) Latency does affect bandwidth in the real-world because of acknowledgements, albeit less so with more modern protocol algorithms.
2) Latency spikes are caused by buffer bloat plus congestion
3) The simplest and cheapest way to fight congestion is to add more bandwidth. Unless you're using WiFi or satellite, bandwidth is easy to add and quite cheap, all the way up to 1gb to 10gb.
Looking forward to the next lesson.
So how was the nest session?
thanks. Was well explained
GOD DAMNIT.
You made me answer a test question wrong. Your bandwidth is THROUGHPUT! Latency doesn't affect Bandwidth.
In fact, throughput is effective output that depends on latency, bandwidth and protocol that's being used. If you protocol needs lots of syncronized end-to-end traffic your throughput will be limited by latency. However, if your protocol does not need any syncronization, it's fully limited by bandwidth.
Bittorrent by default opens way too many flows, that compete with other applications on the consumer's own end, as well as add overhead. I believe that with increasing availability of fast and symmetric connections, the peer count should be limited to between 10 and 30. I think uTP mainly manages the out queue, and is still willing to accept great many download connections.
Great video
Nice
how do we solve these jitter problems from the bandwith getting hoged?????
It seems as though the explanation of Bandwidth is throughput. Bandwidth generally is a fixed maximum rate of transfer which usually does not change unless you bond multiple interfaces. So a 10MB or 100MB or 1GB link is always going to be the same. What you get is generally less that that and would depend on the media, OS, latency etc. The problem I see with adding 10 CD's instead of 1 is that will affect the latency of 720 seconds. The latency will vary.
hey uhh, say I have 1600 max bandwidth, im livestreaming, it takes up 1200 bandwidth, the other people in my house are doing online stuff, taking up the rest, A few hours later I end this livestream, the bandwidth has stopped being used by me, so we have 1200 bandwidth free and where only using 400, (is that correct? Or once you hit peak bandwidth does it not reset for a certain amount of time)?
Whats a DVD?
You might also address buffer bloat. You can find a good explanation on Wikipedia.
Whats the frequency bandwidth of your mic?
hmmm what if we made internet routing similar to the way power plants do it? have extra cables in place used during certain hours of the day that bandwidth use is high and then re rout to those. i think that may help with jitter. although, im pretty sure that would be very expensive.
great vt, i need help bad, ive never used torrents and dont rely watch youtube, i like to play online gaming but in resent weeks i have been unable to put up with the constant disconnecting and lagg that i have stopped playing all together. there are meanny device on my network, im sertan that at least 2 computer on my net work turret and 1 has even opened a DMZ for himself and spends about 6 hours a day on youtube with many videos buffering wile he is watching another, what should i do?
But nice explanation
Noise in video sound -_-
I think you are mixing up bandwidth and throughput
That is right. The bandwidth would be the number of DVDs that are sent at a time.
What is the difference between latency and Ping ? I thought Ping is what you described in the video ! I am confused .
Ping is a tool used to measure latency.
So the less latency the better?
Yes. Latency is basically the amount of time it takes for information to get from one point to another. The lower the latency, the faster
≈ 5:00
A ji(%!£$%‰! INSULT DEATH REBIRTH) tter it is ji(INSULT DEATH AGAIN REBIRTH)
All I understood was Bicycle.
1:41 how's 4.000 MB data per DVD translated into 32.000 MB total data? 8 DVD? Byte? what?
Its Megabyte to Megabit conversion
1mb/s = 8mbps
Audio spikes in your video, please get that sorted
This video is great from a teaching point of view as it uses images, comparisons, and clear definition.
However the sound could be way better which would improve comprehension tenfold.
Please record your voice with a great microphone and environment so we hear all its timbre. Filter out the background noise if needs be using audacity noise filter and use the normalizer and compressor: th-cam.com/video/dQCB72S64L4/w-d-xo.html.
harsh sound !
Abhishek Kumar your videos don’t even have sound idiot
It's a type of sound pollution.the voice is fucking.
Deze kletskous weet ook niet wat jitter si...
5 megabytes a second?? well id be glad for even just 1.5 im running at 700 max kilobytes/sec.
that's crazy. Oh how tech has progressed
Why make an effort to explain b,l,&j if you don't care to provide a decent sound quality
oh come on LOL
latency isnt really the time it takes to get there its more the time it takes to process it just sayin
He is referring to RTT
LOLOLOL
the audio sounds terrible... it's a shame
Bad quality in voice
bad audio
The accent is horrible