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Date:      Sat, 20 May 1995 14:26:35 -0400 (EDT)
From:      Network Coordinator <nc@ai.net>
To:        Mike Pritchard <pritc003@maroon.tc.umn.edu>
Cc:        hackers@FreeBSD.org
Subject:   Re: slow ftp sends over slip link
Message-ID:  <Pine.BSF.3.91.950520142323.2597A-100000@aries.ai.net>
In-Reply-To: <199505201457.JAA00348@mpp.com>

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Try using hardware flow control. It sounds like with FreeFall the latency
is high enough that its not needed, but with your local ISP your modem is
getting thrown 30 or so K of data and then FTP or TCP [I don't remember
which does the error correction in that sort of situtation] realizes it
hasn't been rec'd correctly and resends it. That is why you are getting 
.3K/sec. On the receive side your modem is receiving as fast as it can. 

The same thing should happen if you try to dial up and use a shell 
account on your ISP's machine. Try using rz and sz with a file. Then turn 
flow control on both sides on. 

Well, that is the problem I think of when I see reports like that. Hope 
it helps.

Regards,

-Jerry.



On Sat, 20 May 1995, Mike Pritchard wrote:

> I've seen the following problem with a -current kernel and a kernel
> from a month ago:
> 
> I just noticed that attempting to send out of my machine with ftp
> over a SLIP link is horribily slow (0.3 Kbytes/second if it works at all) 
> compared to receiving a file with ftp (1.4 Kbytes/second).  I got those two 
> speeds sending/receiving the same file to/from freefall. 
> 
> Attempting to send a file via ftp to my local ISP (SunOs 5.4) winds up 
> hanging and never completes.  Anywhere from 0 - 20,000 bytes of the file 
> will make it to the remote host before it hangs.  Receives from this
> host are usually around 1.4 Kbytes/sec.  The file in question is
> a 200K zip file.
> 
> I did notice something interesting if I enable hash mark printing
> in ftp.  Immediately after issuing the "send" command, about 30 hash
> marks will be printed.  This happens if I ftp to freefall, or my
> local ISP's machine.  In the case of ftping to the local ISP's machine,
> maybe 1 or 2 other hash marks will be printed before it winds up hanging.
> 
> In either case, watching the modem lights shows that the modem is sitting
> idle most of the time.
> 
> Some relavant information:
> 
> 1% ifconfig sl0
> sl0: flags=f011<UP,POINTOPOINT,LINK0,LINK2,MULTICAST> mtu 552
> 	inet 128.101.96.75 --> 128.101.118.21 netmask 0xffffff00 
> 2% netstat -in
> Name  Mtu   Network     Address            Ipkts Ierrs    Opkts Oerrs  Coll
> lp0*  1500  <Link>                             0     0        0     0     0
> lo0   16384 <Link>                             8     0        8     0     0
> lo0   16384 127         127.0.0.1              8     0        8     0     0
> ppp0* 1500  <Link>                             0     0        0     0     0
> sl0   552   <Link>                          2746     0     2846     0     0
> sl0   552   128.101.96  128.101.96.75       2746     0     2846     0     0
> 
> 
> I still have problems even if I turn off SLIP compression (e.g.
> ifconfig sl0 -link0 -link2).
> 
> I also tried disabling the rfc1323 and rfc1644 options without
> any luck.
> 
> Anyone have any ideas what is wrong here, or have any suggestions
> on what else I could try?
> -- 
> Mike Pritchard
> pritc003@maroon.tc.umn.edu
> "Go that way.  Really fast.  If something gets in your way, turn"
> 



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