scp strange behaviour

[Sanjaya Balasuriya_1]

Hi all,

I've just installed openssh on my HP server.
Now when I scp a file from HP server to Linux (RHEL 3.0) server, tranfer starts with over 300 KB/s and the speed is rapidly gradually dropped down to a very low value (0.8 KB/s).
And the transfer is stalled.

Any ideas to solve this issue ?

I tried to copy a file to the same Linux server from a Windows machine. It works fine with a more or less stable speed.

Thanks in adavance for any help.

-San

[Andrew Cowan]

Hi San,

This kind of "breathing" behaviour of TCP-IP based comms is quite normal. The link starts of as fast as possible then as buffers fill-up, and the remote acknowledgments take longer to get back, the send window is reduced, and the transmit speed reduced. I suspect that your link is quite slow due to external routing or cabling factors, or the IP Buffers on one of the machines are set too low. Take a look at the "ndd" settings on your HP-server to see if there are any strange settings.

Other things to try are ping, traceroute, and netstat.

[Gerhard Roets]

Hi SAN

Check out the duplex settings between your HPUX server and the switch. If you are talking to a 1000BT card this is not applicable.

Is the HPUX & Linux machines on the same network physical network? It might be a firewall that is having an QOS / Bandwidth shapping rule that is affecting you.

Refer to lanadmin.

Regards
Gerhard

[Sanjaya Balasuriya_1]

Thanks for replies.

I'll check my server.

-San

[Steven E. Protter]

I would expect much better speeds unless you are doing the transfer through a dial up connection.

The prior posts are correct that networking is a possible cause. lanadmin -x lan0 if lan0 is the one doing the transfer.

lanadmin -X will let you change settings on the fly if need be.

This is also possibly a sympton of a failing NIC hard on the hp box. ping the box from Linux. If ping times gradually increase you probably need hardware to do something about the lan.

Also possible is configuration errors on the switch. If on the Cisco switch you set for autonegotiate and you've correctly hardcoded lan setting for your 10/100BaseT hp lan, this can happen.

For 100 BT and below everysetting has to be manual. For 1000 BT and above, every setting, including switch port has to be autonegotiate.

SEP