Slow FTP transmit

[Karl-Johan Halléni]

HP-UX 11.00

I have problems with very slow FTP transmit times. An FTP of a file of 10Mb takes aprox 5 min. There is no problem when receiving a file, i.e putting a file on the system.
The LAN card uses full duplex in 100Mbit/sec.

Thanx in advance / Karl-Johan

[Steven Sim Kok Leong]

Hi,

Check the following network parameter values. You might have to set them higher:

tcp_xmit_hiwater_def - The amount of unsent data that triggers TCP flow control
tcp_xmit_hiwater_lfp - The amount of unsent data that triggers TCP flow control for fast links
tcp_xmit_hiwater_lnp - The amount of unsent data that triggers TCP flow control for slow links
tcp_xmit_lowater_def - The amount of unsent data that relieves TCP flow control
tcp_xmit_lowater_lfp - The amount of unsent data that relieves TCP flow control for fast links
tcp_xmit_lowater_lnp - The amount of unsent data that relieves TCP flow control for slow links

Also, you can install something like iperf to verify your network throughput. Download it from:

http://dast.nlanr.net/Projects/Iperf/

Hope this helps. Regards.

Steven Sim Kok Leong

[Ron Kinner]

The most common reason for a difference in out vs in speeds is a mismatch between the NIC and the Switch. Autonegotiate doesnot always work and then you get one end set to full and the other set to half.

Lanadmin
lan
display
will tell you a lot about your connection. If you see collisions then obviously you are not running full duplex. If you see no collisions and a lot of errors then the other end is running half. There is a command line option to use lanadmin to set the duplex but I'm not at work so don't have that handy. Check the man for lanadmin. You will also need to modify netconf down in /etc/rc.config.d to make the change permanent.

If you manually set the duplex on the PC you must set it on the switch too

Setting it on the switch will depend on who makes your switch. I can help you on Cisco and 3COM but otherwise you are on your own. If your switch does not have any management options then go back to autonegotiate and see what happens. It should have a light on the port which tells you FD or hd.

Don't forget that there is a possibility of the same problem at the other computer too.

Ron

[T G Manikandan]

Hello,
Ron is right.one of the reasons are
When you find mismatch between the speed of the network nic and the switch.
You have mentioned that the speed of the network card is 100Mbps.What is the speed setting of the switch/hub which connects that>
Just check your machine speed using the lanadmin command

[Steven Sim Kok Leong]

Hi,

As the rest have stated, a failure to auto-negotiate the proper speed (either because the server is set to auto-negotiate or the switch is set to auto-negotiate) is one possible reason that you will receive errors.

Does netstat -i show a high packet error count. Is this count increasing?

If you are unsure, hardcode the duplex mode on both ends of the communication. Subsequently, perform a FTP or iperf test. Also, check for any packet errors via netstat -i.

The following article explains this concern in detail:

http://www-commeng.cso.uiuc.edu/docs/autosense/autosense.html

/quote/

If there is a duplex mismatch, and one end of the link is in full-duplex mode, and one end is in half-duplex mode. The half-duplex side of the link will not transmit data while it is still receiving data from the other side. The full-duplex side of the link has no such restriction, however, and will transmit the instant data is avaliable to send-- it will not wait for the other side to stop transmitting before sending its own data. If the full-duplex side does this, the half-duplex side will start to receive data before it is finished with its own transmission. Seeing data on "both sides of the line", the half-duplex interface assumes a collision has taken place, discards the incoming packet, and counts it as an error.

/unquote/

Hope this helps. Regards.

Steven Sim Kok Leong

[Karl-Johan Halléni]

netstat -i
shows:
Ipkts Opkts
813831 804314

and the lanadmin/lan/display
shows:
Description = lan0 Hewlett-Packard 10/100 TX Half-Duplex TT = 1500

Ethernet-like Statistics Group

Index = 1
Alignment Errors = 0
FCS Errors = 0
Single Collision Frames = 303
Multiple Collision Frames = 6
Deferred Transmissions = 565
Late Collisions = 2661
Excessive Collisions = 0
Internal MAC Transmit Errors = 0
Carrier Sense Errors = 0
Frames Too Long = 0
Internal MAC Receive Errors = 0

So, the problem is that the servers LAN card is running half duplex and the switch is running full duplex.

I now need to set the LAN card on the server to full duplex but don't know how yet. I've looked in man for lanadmin but didn't find any help there.

Any one have the solution?

Thank you very much for your help!!!

/Karl-Johan

[harry d brown jr · Accepted solution]

Karl,

go into "sam"

Select "Networking and Communications"
Select "Network Interface Cards"
Select your network card
Turn duplex to full, you might have to turn autonegotiate off.


live free or die
harry