error correction

[Ultraworld]

Don't we think that it is quite amazing that all the data we send over the internet is transfered correctly and that no errors occur.

mp3s, patches, mp3s, this forum content, mp3s, pictures, etc.
It all goes perfect.

 

[Hakim]

Especially nice is it that nowadays, with some software, you can pull the plug during transmission, restart it later and still get a complete file.

 

[ainwood]

There are errors, you just don't see them.

Data packets are checked to see if they arrive correctly. If not, then the data is requested again and again. You don't see this, but it happens behind-the-scenes.

 

[Ultraworld]

Originally posted by ainwood
There are errors, you just don't see them.

Data packets are checked to see if they arrive correctly. If not, then the data is requested again and again. You don't see this, but it happens behind-the-scenes.

yes that is what Im talking about

 

[The Last Conformist]

UW: You've never got a corrupted DL? Lucky you ...

 

[Ultraworld]

Originally posted by The Last Conformist
UW: You've never got a corrupted DL? Lucky you ...

well: it happened quite frequently that someone just turned his compu off while I was downloading, but corrupted files? no!

 

[Akka]

(in fact, when you see the incredible number of error-checking systems, you just understand how many errors probably have happened with you not realizing it...)

 

[Ultraworld]

Originally posted by Akka
(in fact, when you see the incredible number of error-checking systems, you just understand how many errors probably have happened with you not realizing it...)

but they all got corrected

 

[Akka]

Not all, but nearly.
But now, if you really want to be impressed, you should see what is the part of significative data that is transmitted...
That is somehow much more depressing

 

[bobgote]

like ainwood said, it's all in the transfer protocol. it checks every arriving packet for errors and resends if necessary. you probably do get quite a number of errors, but if you noticed anything, it'd probably just be that it takes a little longer.

 

[Comraddict]

There is error correction - of 8 bits one is for error correction. Digital systems are less prone to erorrs, cause noise don't infuence much decision making whether it is 0 or 1.

 

[Akka]

There is much more error correction than one bit out of eight ^^

 

[Knight-Dragon]

Moderator Action: Moved to Comp Talk.

 

[crystal]

Majority of the data you see on Internet is transmitted with TCP/IP packets. Every one of them contains a 16-bit checksum in their header field which usually ensures that no data is corrupted. Packet receiver always recomputes the checksum, and if it doesn't match the one in the packet header, retransmission for the packet is requested.

More info on the transmission control protocol

And here is the RFC if you want to know every technical detail

Some applications go even further than this and compute their own checksums for the entire file that is being transmitted.