Re: [Help-gnunet] strange upstream values

[Nathan Lutchansky]

On Thu, Sep 05, 2002 at 11:30:26PM -0400, Leonard wrote:
> Thu, 5 Sep 2002 11:41:53 +0200 (CEST), Christian Drechsler <address@hidden> a 
> miaul? :
> > hm, very strange ... my adsl line theoretically has a maximum throughput
> > of 128 kbit/s upstream. there is much traffic on gnunet at the moment, so
> > my connection gets quite loaded sometimes. wmpload sometimes shows values
> > way above 128 kbit/s, the highest i saw being 171 kByte/s (bytes, not
> > bits!) upstream. how can that be possible? i don't think the PPP
> > compression can achieve such rates with encrypted data, can it?
>
> I had the same thing happend to my cable-modem : up to 176 KB/s upstream
> UDP is apparently not limited.

Um...  UDP is not like TCP.  Your IP stack is perfectly happy to keep 
accepting UDP packets as fast as you can throw them and it will pass them 
all to the cable/DSL modem over the Ethernet link.  But if your modem 
finds that not all of the packets will fit into the line, it will simply 
drop them, and there's no way for your computer to determine which packets 
were dropped, or even how many.

TCP handles this by acknowledging each packet and resending the packets 
that were dropped.  UDP is just a dumb protocol, so without adding support 
for acknowledgements into your application itself, you will never know how 
many packets are dropped.  -Nathan

-- 
Help reduce spam!  PGP-sign your email.

pgp5StNbTNiP9.pgp
Description: PGP signature