[nas-2000] AW: Slow ftp bin transfer problem
- From: "Tuchscheerer, Sven (K-EFFI/P)" <sven.tuchscheerer@xxxxxxxxxxxxx>
- To: <nas-2000@xxxxxxxxxxxxx>
- Date: Wed, 27 Feb 2008 17:35:20 +0100
Hi Alfred,
did someone forward the Problems written above to the proftpd "Engeneers"?
As I know this pretty lightweight server is open source. Therefor I guess
there´s @least a moderate Group who can give some input to problem (not the
solution - this might be like christmas ;-))
greetz. Sven
-----Ursprüngliche Nachricht-----
Von: nas-2000-bounce@xxxxxxxxxxxxx [mailto:nas-2000-bounce@xxxxxxxxxxxxx] Im
Auftrag von Alfred Bruckner
Gesendet: Mittwoch, 27. Februar 2008 15:08
An: nas-2000@xxxxxxxxxxxxx
Betreff: [nas-2000] Slow ftp bin transfer problem
Hello,
we are trying to find a solution for the "slow ftp bin transfer problem"
There is also a German post at the nas2000 forum:
http://nas2000.homeunix.com/thread.php?postid=464#post464
Many users have the problem that ftp download through an internet connection
from the NAS may be very slow.
Test setup:
PC - Internet - ADSL modem - Router - Switch - NAS
Port forwarding (20,21) is configured for modem and router.
I traced the packets sent/received from NAS (connected sniffer with HUB
between Switch and NAS)
What I know already:
- ascii mode transfer is fast, bin mode may be slow
- on local net ftp is fast
- it is caused from too large packets sent from the nas
NAS always use packet size like if MTU=1500
e.g. NAS sends two large and one small packet - the two large ones are
rejected with "fragmentation needed" and the smaller one passes
--> retransmission...
- MTU setting of ifconfig is ignored by ftp in bin mode
In ascii mode packet size is reduced accordingly
- MSS setting of route command is ignored
- MSS setting with SocketOptions in proftpd.conf is ignored
- most PPPoE connections need a setting of MTU=1492 because of 8 bytes
overhead. That corresponds to MSS=1452.
- same behaviour for Tinky and RS Firmware
What I don't know:
- how to tell proftp or the NAS to reduce the packet size as if MTU=1492
Any ideas?
HWguru (Alfred)
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