Re: How to use TCP window autosizing?

[christos%astron.com@localhost (Christos Zoulas)]

In article <20150804102747.GA9451%azeotrope.org@localhost>,
Dave Huang  <khym%azeotrope.org@localhost> wrote:
>So it turns out NetBSD's TCP window autosizing works fine after all...
>apparently the problem is scp. I was able to get about 6Mbytes/s
>throughput by transferring the file via HTTP. While the file is
>transferring via HTTP, netstat on the remote Linux end shows about 4MB
>in the "Send-Q". Whereas while it's transferring via scp, netstat
>shows only 32K or so in the Send-Q.
>
>According to http://www.psc.edu/index.php/hpn-ssh , "SCP and the
>underlying SSH2 protocol implementation in OpenSSH is network
>performance limited by statically defined internal flow control
>buffers." I'm not too sure why I was able to get OK performance using
>PuTTY's pscp on Windows, but that page also says, "HPN clients will be
>able to download faster from non HPN servers." Perhaps PuTTY doesn't
>have the same bottleneck as OpenSSH, so it's able to download faster
>even with the slow sshd.

$ telnet quasar.astron.com 22
Trying 2604:2000:efc0:5:9998:523c:d378:8572...
Connected to quasar.astron.com.
Escape character is '^]'.
SSH-2.0-OpenSSH_6.9 NetBSD_Secure_Shell-20150602-hpn13v14-lpk

christos