Date: Fri, 5 Oct 2001 15:04:12 -0700 (PDT) From: Joe McGuckin <joe@monk.via.net> To: questions@freebsd.org Subject: FTP server problem ? Message-ID: <200110052204.f95M4CJ73523@monk.via.net>
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I have approx. 100 users coming in to my network via PPPOE.
There's an interesting anomaly that shows up when any of these users
attempt to retrieve a file from one of our ftp servers.
(I verified this with my linux laptop also)
The typical setup is as follows:
A B C D
PC --- PPPOE Router ------ Gige Switch -(fiber)- Gige Switch --- Cisco 7200 --- Switch --- Cisco 7200 --->>> Internet
LinkSys, etc PPPOE sessions |
Performs NAT also terminate here. |
|
FTP server
FTP downloads from ftp.mozilla.org average about 4Mbits/sec
FTP downloads from my ftp server average about 90 kbits/sec
Scenario #1: PC or linux laptop at location 'A'
(Using PPPoE and NAT)
When performing downloads from mozilla.org, the PPPOE router activity light
blinks constantly, indicating uninterrupted thruput.
When downloading from my ftp server, there a flurry of blinks, then a 5 second
pause. This sequence repeats until the transfer is completed.
Scenario #2: Linux laptop at location 'B',
(No PPPoE or NAT involved)
Ftp tranfers to my ftp server run at about 10 Mbits/second
Ftp transfers to mozilla.org run at about 4 Mbits/sec
The questions are:
1) When ftp'ing behind the PPPoE router, why is my ftp server exhibiting
slow transfers with multi-second delays between packets? Why doesn't
mozilla.org exhibit this behavior?
2) What tcp/ip setting could the PPPOE router impose that would cause this
poor performance by my ftp server? MTU setting?
3) What further staps can I take to debug this? Are there any tcp debug flags or
ftp setting I could try ?
Thanks,
Joe
--
Joe McGuckin
ViaNet Communications
994 San Antonio Road
Palo Alto, CA 94303
Phone: 650-213-1302
Cell: 650-207-0372
Fax: 650-969-2124
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