i have noticed that my LAN is only transferring date at ca 4-5 Mb/sec, and lately it has not been over 1.5!! it is very unstable. when i move a file across my LAN, the rate is between 0 and 300 K, moving up and down all the time! I have 100 Mb adapters connected to a 100 Mb switch. It should be able to have a higher speed that that!

what is wrong?? what can I do??

If it doesn't go over 1.25MB/s(close toe the 1.5 of you) it means that you're network doen't change to 100Mbit but is stuck on 10Mbit. This will most probably be a cable problem. Is this a good cable, some cables are not as good as others and may cause this problem and also check that the cable isn't over a 100 meters long.
Look at you're switch and check if it doesn't have a 10/100Mbit indicator light. Maybe it's also wise to change port on the switch once (if you have any free ones)

i believe my cables are cat. 5, but i'm not sure...have to check when i come home from work. they are definitely not more than 100 meters!!
there are light indicators on the switch, and they say that the nw is 100Mbit. I'll try to change ports and see if it helps.

but cat. 5 cables should support 100Mbit, right??

The cables should be ok but it wouldn't be the first time that a cable problem slows down a whole network. If it's possible you try to connect the computers directly without the switch to check that the switch isn't a problem.
Theoreticly you should be able to get 12.5MB/second. But if you get 8 to 10 you're connection is working good.
Problems that can slow it down.
- Bad cables that couse a lot of collisions can slow down an network very hard.
- One of the network adaptors or ports on the switch that does not support 100Mbit will slow all the involved network addaptors down to 10Mbit
- Sending a lot of small files will not allow you to get high speeds. Because a netork transfer starts slow and goes faster and faster untill one of the computers or switch involved can't keep up. If the files are to small the transfer will already be completed when the connection should get to a high speed.
- Very old computers (368, 468) that can't handle a fast data transfer. I don't think that should be a problem. Just did some test and my old PentiumII 300 can handle 10 MB/s.
- When you're writing to partitions that are very fragmented you can have some sower traffic but that should not be a problem on a newer computer because even when with a very fragmented harddrive a newer computer can write a lot faster than you're network connection can handle
-Virus scanners checking every file that come's in or that goes down. Seen it a week ago with a friend of mine, after he disabled his virus scanner the transfer went fom 2.5MB/s to 10MB/s. Don't do this if you're not 100% shure that the file's that you're transferring are not infected.

ok, thanks...i'll have a look when i get back home.

- Bad cables that couse a lot of collisions can slow down an network very hard.
Possible...but the connection has become worse...it was good earlier. it is cat.5 cables

- One of the network adaptors or ports on the switch that does not support 100Mbit will slow all the involved network addaptors down to 10Mbit
All ports/nw adaptors support 100Mbit. though im not sure if the adaptor on my SuSE box is running @ 100Mbit, how can i check this?

- Sending a lot of small files will not allow you to get high speeds. Because a netork transfer starts slow and goes faster and faster untill one of the computers or switch involved can't keep up. If the files are to small the transfer will already be completed when the connection should get to a high speed.
I have tried sending DVD isos, with same poor result...

- Very old computers (368, 468) that can't handle a fast data transfer. I don't think that should be a problem. Just did some test and my old PentiumII 300 can handle 10 MB/s.
I have one P4 and one Duron

- When you're writing to partitions that are very fragmented you can have some sower traffic but that should not be a problem on a newer computer because even when with a very fragmented harddrive a newer computer can write a lot faster than you're network connection can handle
Both OS's are less then one month


-Virus scanners checking every file that come's in or that goes down. Seen it a week ago with a friend of mine, after he disabled his virus scanner the transfer went fom 2.5MB/s to 10MB/s. Don't do this if you're not 100% shure that the file's that you're transferring are not infected.
I have Norton Antivirus on one computer, I will have to try to disable it