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Re: [Discuss-gnuradio] more gmsk issues


From: Brett Trotter
Subject: Re: [Discuss-gnuradio] more gmsk issues
Date: Mon, 22 Jan 2007 07:01:48 -0800 (PST)



Patrick Strasser wrote:
> 
> Some more notes... It's been very late when writing this.
> 
> Patrick Strasser wrote:
>> In general TCP is quite capable 
>> of recovering from lots of errors, but it's busy with itself for this 
>> purpose, which leaves less capacity for its payload. IP does not correct 
>> errors, only detects (checksums). This leaves possible error correction 
>> to layer 2 and 1.
> 
> Of course the application has to take care of errors. If some errors 
> survive the application has to cope. Some do not care at all, like video 
>   and audio streams: If data is lost, no retransmission is tried. The 
> human brain has to interpolate missing information and thus do the error 
> correction.
> 
>> In layer 2 we have a mixture of Ethernet and a back 
>> off algorithm[..]
>  > Note:
>> AFAICS check for successful transmission is done.
>          ^^^^
> Of course I meant "_No_ check for successful transmission is done."
> 
> Patrick
> -- 
> Engineers motto: cheap, good, fast: choose any two
> Patrick Strasser <patrick dot strasser at  tugraz dot at>
> Student of Telematik, Techn. University Graz, Austria
> 
> 


I appreciate all of your insightful comments, but here's where I'm confused.
NFS, FSP, and TFTP all use UDP and should have acknowledgement, verification
and resend capability- and all of those seem to get tied up after X bytes of
transfer, depending on MTU, bitrate, etc. It seems that for a given setting,
I can only transfer a very specific number of bytes of data. Before, during,
and after the transfer, I can ping with 1k payloads until the end of time-
and despite the fact that FSP and TFTP don't create a connection of any
kind, they get bogged down like SCP did when I was trying TCP transports.

So the bottom line question is why in the heck would a file transfer over a
stateless protocol get frozen after a certain number of bytes when it
appears I can ping with large payloads indefinitely?

For the record, anything terribly deep in python or networking code is
beyond me- so aside from simple settings tweaks and protocol/application
selection to garner stability, I'm probably out of my league.
-- 
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