FTP over ATM issue

UNIX for Advanced & Expert Users
1

We just recently upgraded our T1 wan link to a 10Mbit ATM link.

Windows pc's seem fine and get great speed, however we have 2 Sco unix box's that seem really slow at FTPing now.

both Sco box's are

SCO OpenServer Enterprise System (ver 5.0.5m)
compaq ML530's

I'm not really sure what to check...

I did an identical file transfer to the same pc on the other side of the wan. My windows box was getting around 180k/s but the 2 sco box's were only getting around 30k/s.

I'm not sure why when we did the cut over from T1 to ATM the unix servers acted different. Will a reboot of the unix servers make a difference?

Any help would be great.

Thanks

2

Hi,

I think it's time to upgrade to a different type of Unix server :slight_smile:
No, just kidding.

ATM has the nice feature of rebuilding your packets to transfer to the other site and over there it goes visa versa. A kind of MOdulate DEModulate :slight_smile:

It might be that the mtu from your system is conflicting with the size ATM is using, I know you can let this being addapted by your ATM provider. Adapting the MTU size of your packets is addaptable as well (temporarily) using ifconfig. I think it is very wyse to wait to get some more (different) answers from multiple people as this does not looks to be an easy problem. If nothin else comes out I'dd defintly try to get in contact with a specialist from your ATM provider.

Good luck.

Regs David

3

Try a transfer from your local pc to your local sco box. This will, I hope, not involve ATM. How fast is that?

4

Here is a transfer of a windows file from my 2k PC to my Sco box

150 Opening BINARY mode data connection for Q311401_IIS5_SP2_x86_ENU.exe.
17328032 bytes sent successfully. (5640.64 KB/s) (00:00:03).

5

We don't really have any SCO experts and I'm not sure what to tell you. But here are a few thoughts.

First check the local lan as SCO sees it. Try "netstat -i" at least and look for excessive errors or collisions. The box needs a good connection to the lan. Things may have been reconfigured that caused a problem. Also sco may have some addition stats that can be displayed by an additional command. Look for anything like that. And check the traffic flow to/from the box. If the box is doing 15 other concurrent ftp jobs, your job is going to be slow.

Still got a problem? Unplug the sco box for a while and take your pc over and plug in into the sco's network connection. Reset your pc to sco's ip address. Send the file. If it's fast from your pc and slow from the sco, you know that the problem is on the sco. If the pc is also slow, there must be a network issue near the sco.

If the problem is on the sco box, make sure that your os is up-to-date. No fair comparing a 15 year old unix to a recent pc. And make sure that your os has all networking patches. Look around on the sco and see if you can find any way to tune tcp/ip. For example, sun and hp have ndd which can do that.

That's about all I can think of. If you get it working faster, let us know what the problem was.