Re: Ramfs and Cachless Networking.
On Wed, Sep 26, 2001 at 07:50:32PM +0200, Viktor Rosenfeld wrote:
> I suspect that the problem lies with scp. On my local network I
> experience transfer rates of less than 200kB/s with scp because the
> server is an old Pentium 133 with not enough horse power.
Well, yes... scp is an encrypted protocol. Encryption takes time to
perform.
> With plain
> old rcp I get up to 6MB/s on a 100MB (half duplex?) link.
A data transfer rate of 6MByte/sec on a 100Mbit/sec link sounds
pretty reasonable. 6MByte = 48MBit, plus you've got packet headers
eating bandwidth, the possibility of collisions[1] and dropped
packets, and good old-fashioned latency to take their bites out of
your nominal 100Mb/s rate.
BTW, duplex doesn't figure very prominently here. Full duplex would
just allow you to independently send 100Mb/s and receive 100Mb/s, but
would not allow sending at 200Mb/s. It would help in this case by
reducing the chance of collisions, but headers, dropped packets, and
latency would be unaffected by it.
[1] In typical usage, ethernet's not good for much more than 60-75% of
its nominal bandwidth due to collisions, but I would expect to see
more than that out of a point-to-point link or a segment that's
otherwise idle.
--
When we reduce our own liberties to stop terrorism, the terrorists
have already won. - reverius
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