[Mldonkey-users] feature suggestion: forward error correction

[Goswin Brederlow]

Hi,

I have a feature suggestion that I'm missing in all the P2P protocol:

Forward Error Correction.

The Idea of FEC is to create some extra redundant chunks for each file
in a way that lets one detect and correct errors in previous chunks. A
nice extra is that you can also correct missing chunks by just
assuming them to have the errors.

If the file has N chunks and you create an extra M chunks, any N of
those N+M chunks are sufficient to restore the original file.

So why would we want to do this? We have checksums per block and can
detect errors and redownload the block. So FEC isn't realy needed you
might think.

BUT, the more blocks a file has, the more likely another client has a
block you don't yet have. Since you don't need all blocks of a file to
restore it those ugly red bars also don't mater that much anymore. And
sometimes you have a checksum error in 2 or more blocks. If the faulty
bits in those blcoks aren't in the same place a single extra block can
repair them all. Instead of downloading 2 or more blocks you only need
1.


Would you be willing to expand the mldonkey protocol to include an FEC
feature? Do you think we could get edonkey2000 to extend the original
edonkey protocol with such a feature?

MfG
        Goswin