[Udpcast] Reliable multifile transfer over slow links, downed hosts

Alain Knaff alain at knaff.lu
Fri Oct 17 14:00:58 CEST 2003


On Friday 17 October 2003 02:37, Christopher Curtis wrote:
> Hello,
>
> I've been looking for an application for some time now that doesn't seem
> to exist.  The more I search, the more links lead to udpcast.  My
> scenario is basically this:  I need to reliably transfer large files
> (large as in >2GB) to multiple hosts over a slow WAN.
>
> I've read some of the messages in this list regarding FEC and retries,
> but I don't think this is sufficient.  I've also looked into rsync batch
> mode without much success (I expect the directory layouts to be
> different).  And in the background I keep thinking about BitTorrent.
>
> What I would ideally want is something like the following:
>    'N' clients, each running a daemon (or inetd...)
>      Server Process connects via TCP to each client
>      Server tells client "Listen on Multicast port <foo>"
>          "I am going to send you XXXX bytes"
>          "Save this in a file called <bar>"

You could set up something like this with ssh starting udp-receivers
at the various "clients":

 ssh udp-receiver -p 9002 -f bar ... >stdout.log 2>stderr.log

The stdout.log and stderr.log (and similar output from the server)
will help you to assess how many packets are retransmitted (some
postprocessing would be needed, because this output is intended for
direct display on terminal, so you may need to stip out the escape
sequences to get the data into a processable form)

Alain




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