Slowness of establishment of connection ftp

[Arnaud_6]

Bonjour,
je souhaiterai connaitre une moyen de r??sorber les probl??mes de lenteurs pour ??tablir une connection ftp.
Merci de votre r??ponse.
Arnaud

............
Hello,
I would like to know, how I can reduce the problems of slowness of attempt of connection ftp.
Thank you for your answer.
Arnaud

[Stefan Farrelly]

In my experience these are nearly always caused by autonegotation being turned ON for your network card. Weve always found it faster and more reliable to set your network card to a fixed 100Half-Duplex, and set it the same on your Switch/Hub its connected to.

[Fragon]

BTW,I think you must check your network infrastructure! For a long time, I get a fast speed from getting files from the server, but a poor speed for putting files to the server. And at last I found it's the network problem.

-Gerald-

[Alan Casey]

Le document suivant peut-etre util...

http://support4.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000042500802
______________________________________________
DOCUMENT ID: 2952729
DOCUMENT REVISION: 2
DATE: 20JUL1999
ALERT STATUS: Yellow
INFORMATION TYPE: Problem Reference
DISTRIBUTION: Public Released
NOVELL PRODUCT CLASS:
Connectivity Products
NetWare
NOVELL PRODUCT and VERSION:
UNIX Connectivity
NetWare 4.11

ABSTRACT:
NA

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DISCLAIMER
THE ORIGIN OF THIS INFORMATION MAY BE INTERNAL OR EXTERNAL TO NOVELL. NOVELL MAKES EVERY EFFORT WITHIN ITS MEANS TO VERIFY THIS INFORMATION. HOWEVER, THE INFORMATION PROVIDED IN THIS DOCUMENT IS FOR YOUR INFORMATION ONLY. NOVELL MAKES NO EXPLICIT OR IMPLIED CLAIMS TO THE VALIDITY OF THIS INFORMATION.

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SYMPTOM
The customer was running a NW 4.11 server with a 100 MB Network
Interface Card (NIC), plugged into a 10 / 100 MB auto-sensing
switch. In addition to the normal IPX communication of NetWare
4.x, the server was doing TCPIP communication and acting as an
FTP server. However, FTP sessions (especially file transfers)
seemed extremely slow.


The problem did not occur if the customer ran the Server's NIC at
10 MB.


TROUBLESHOOTING

Items that should be checked in a case of slow communication on
100 MB Ethernet:
(1) Turn off the auto-detection of NIC speed at both the server
and at the switch port (specifically set both to the correct
speed). Some switches appear to continually renegotiate speed,
which can degrade performance.
(2) Try changing to half duplex (instead of full duplex) on the
server NIC.
(3) Try setting the card (and possibly the switch) to 10 MB
Ethernet. Is it performing better than the 100 MB? This is not
necessarily considered a 'solution' but it is another indication
that the problem is related to the NIC or switch configuration.
(4) Verify the LAN drivers are up-to-date and written to the
latest ODI spec. (*.LAN, ETHERTSM.NLM, MSM.NLM, NBI.NLM)
(5) Try placing a 100 MB hub between the server and the switch.
(6) Try different NIC, a different cable, a different port on the
hub, etc., to isolate and eliminate possible hardware problems.
SOLUTION
The customer placed a 100 MB hub between the server and the
switch, which solved the problem. The exact nature of the
problem (as well as why the hub helped) were not determined.


This type of issue is generally hardware related, not OS related.
It has been seen between NT Servers and switches as well. See
the trouble shooting section for several possible configuration
variations that can help.

[Arnaud_6]

Thank you very much for your answers.
Only question:
Why when I add the ip of my customer ftp in /etc/hosts the access times are immediate?
Thank you for your answer.
Arnaud

[Stefan Farrelly]

If adding the IP to your hosts file made it much faster then its a DNS lookup problem. Your DNS server must oscasionally be slow causing your problem - and by adding it to your hosts file your /etc/nsswitch.conf file must be looking in hosts first.

I would get whomever looks after your DNS server to investigate why its slow sometimes (probably just overloaded). But you have a good workaround by adding stuff to your hosts file.

[Bill Hassell · Accepted solution]

To verify your DNS server, use nslookup. It appears that you have files then dns configured in /etc/nsswitch.conf (which is very good). Look in /etc/resolv.conf: do you have 2 or 3 servers listed? If so, the first server may be dead or not running properly at all. In that case, DNS queries will have to timeout, about 20 seconds before it tries the next DNS server.

You can verify that the first server is broken with:

nslookup some-hostname-or-IPaddr first-server-IPaddr

If nslookup hangs, then reports an error, take out the first DNS server--it's worthless.

[rick jones]

and if you do find that your DNS server is overloaded, some of these papers may be of help:

ftp://ftp.cup.hp.com/dist/networking/briefs

if you have an inetd.sec file active I think that inetd will do reverse lookups to check hostnames against the allowed lists. it is also possible that the ftpd is configured to do this too. i suspect that somewhere in one of the ftp config files you could disable revers IP lookup by the ftpd, and if you get rid of inetd.sec (or tcpwrappers if you are running it) then the reverse lookups may go away.

to see if inetd is doing reverse lookups take a verbose tusc trace from rev 7.3 of tusc (from ftp.cup.hp.com) and look for stuff to port 53. you can do the same thing to the ftpd, but it is more difficult - ftpd is launched by inetd, so you would actually tusc the inetd and tell tusc to follow forks - and best to have tusc display pids in the output.