HPN and None options in OpenSSH

[Kevin Oberman]

On Sat, Jan 23, 2016 at 7:55 AM, Dag-Erling Smørgrav <des at des.no> wrote:

> Julian Elischer <julian at freebsd.org> writes:
> > what is the internal window size in the new ssh?
>
> 64 kB.
>
> DES
> --
> Dag-Erling Smørgrav - des at des.no


Are you sure of this? I have not looked at the code, but my former
colleagues at the high performance research network ESnet claim at
http://fasterdata.es.net/data-transfer-tools/say-no-to-scp/  that the
internal buffers and effective window size have recently been increased
from 64KB to 1MB an allow for transfer rates of up to 140 Mbps over a link
with 53 ms. latency. With the HPN patches, they report 1.2 Gbps, making HPN
patches still significant over high latency paths.

That said, scp still performed poorly when compared to other technologies
(i.e. GridFTP) for bulk data transfer over high-latency high-bandwidth
links. (ESnet provides links of up to 400 Gbps between the US and Europe as
well as within the US, so this sort of thing is quite important to them.)
--
Kevin Oberman, Part time kid herder and retired Network Engineer
E-mail: rkoberman at gmail.com
PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683