Netgear switch problem

[Tobis]

Hi
I have a problem with my home network not reaching top speed when connected through my daisy chained switches.
Here's the problematic layout. Its kind of hard to make a sensible description.

Wall outlet 100Mbit - Cable modem - Netgear WNR 3500 Router - 1 PC connected. Lets call it PC1
From router - Netgear GS605 v2 Switch - (Im planning to move PCs to this switch thats why Im daisy chaining)
from switch above - Netgear GS605 v4 Switch -
2 Win 7 64 PC Gigabit NIC and a XP 100Mbit NIC connected. PC2, PC3. PC3 is acting serverish. The XP is irrelevant.
All wiring is Cat5e some FTP some UTP, all indicator LEDs on NICs and Switches shine green indicating Gigabit speeds.

PC1 gets ~90Mbit to Internet with tests like speedtest.net and others.
PC1 get ~5 MB/s in file transfers from PC3.
PC 2-4 get ~2 Mbit at PC2-4. File transfer between PC2 and PC3 is about 100MB/s as expected.
If I circumvent the last router and connect PC2 straight to the v2 router with the same cable I get top speeds to the Internet, ~90Mbit.

Im not a networking expert, but I've been around PCs for 15 years and know the basics, so feel free to treat me like an idiot if you think it can help me find out whats wrong.

 

[Fardringle]

Where are you that you are getting a 100 Megabit cable connection?

That aside, the huge drop in speed between the first and second switches tells me that you probably have a bad patch cable between the switches. Either that or a speed/duplex conflict. Also, the slow connection to PC4 suggests you may have a bad cable or duplexing issue there as well.Try new cables in the trouble spots and make sure ALL devices are set to auto-negotiate speed and duplex settings.

 

[Fallen Kell]

...and make sure ALL devices are set to auto-negotiate speed and duplex settings.

In 1000BASE-T network, there is no such thing as half-duplex or forced manual settings (it must use auto-negotiate).

http://en.wikipedia.org/wiki/Gigabit_Ethernet#1000BASE-T

But you are correct on the cables. It is probably an issue with them.

 

[Fardringle]

Gigabit switches and NICs can be set to manual speeds. They shouldn't be set that way except in the rare situations where it's actually needed, but they do have the option, which is why I said to check to make sure they aren't configured improperly. New cables are the first and easiest thing to test, then move on from there to other possibilities such as speed/duplex settings, NIC drivers, and possibly bad hardware in the second switch and/or PC4.

 

[Tobis]

Where are you that you are getting a 100 Megabit cable connection?

In Sweden of course!
Its a fiber connection to the wall outlet and the "cable modem" could be something else.
All PCs are tripplechecked for auto negotiate. Have tried to set it to 1000 to no avail.
Ill recheck all cables then, but my switches tell me I have a green light for gigabit, and Ive tried with Cat5 cabling which gave me an amber light indicating 10/100Mbit connection so the indicators work.

 

[Fardringle]

The indicator lights just mean that the switch and the computers agree that they want to talk at a certain speed. It doesn't mean that the cables are OK. I really would try new cables between the two switches and between PC4 and the second switch since those are the spots where you are having problems.

 

[Tobis]

Update:
Tried file transfer between PC1 and PC3 bypassing the v2 switch. 100+ MB/s transfers was the result. All cabling unchanged. With the v2 switch I got a max 10 MB/sec depending on what port I use.
I think I have to conclude its the old switch that's the culprit.

Anyone have an idea how to check the switch for errors?

 

[Tobis]

The indicator lights just mean that the switch and the computers agree that they want to talk at a certain speed. It doesn't mean that the cables are OK. I really would try new cables between the two switches and between PC4 and the second switch since those are the spots where you are having problems.

I would disagree since trying to gigabit with inferior cables say cat5 or poorly crimped ones would result in the switch telling me with the amber light I only get 10/100.

I would try new cables if it werent so damn long ones I need. Ive tried moving some equipment to test at closer range wich resulted in my previous post.

 

[Fardringle]

I just replaced a network drop last week that would negotiate at gigabit speeds but never actually transferred any amount of data because it was getting close to 50% packet loss due to a broken wire inside the cable. Bad cables are by far the most common cause of network connectivity and speed problems which is why they are almost always the first thing to test.

It is possible that the switch is failing, but I wouldn't focus on that until you are able to confirm that the cables are OK. Moving equipment close together to use short cables is a reasonable way to do that if you can't get (or don't have) spares that are long enough to reach the original locations. If you get the same results using known good cables on the second switch, then you can look at the switch itself as a possible cause of the problem. Unfortunately, there doesn't appear to be any diagnostic software or built-in utility for that switch so without the proper tools the best you can do is some trial and error with good cables between the computers on different ports of the switch.

For example: You know that PC4 has trouble. Connect PC2 or PC3 to the port on the switch where PC4 is located right now and transfer files between 2 and 3 to see if they still work properly or if they start to have problems. Connect PC4 to the port that PC2 or PC3 are using now and test PC4 to see if it starts working properly on a new cable on a different switch port or if it continues to be slow. Connect the patch cable between the two switches to different ports on each switch (move one at a time) and test transfer rates again between PC1 and the other computers.

If the problem seems to stay with certain ports on the switch (PC4's port is always slow no matter which computer is connected, even with new cables) that's a good sign that the port on the switch is going bad. If PC4 stays slow even with a new cable on a different switch port, that probably means the NIC in PC4 is going bad, or there is a driver/software problem on the computer.

If you want to get a little more detailed, or if simply swapping cables doesn't narrow down the source of the problem, try using Wireshark on the network to see what - if any - packet errors you are getting when you transfer files between the machines.

 

[Tobis]

Fair enough, I stand corrected.
Installing Wireshark now.
Tried it when it was called Ethereal many years ago but couldnt wrap my head around it but Ill try and see what happens. Any tips on what to look for?

Edit: On the rest of your post, I think I've tried most configs of switch placements/ports and as I said, when using only the new switch going from PC1 - router - switch - PC3 I get the full 100+MB/sec thoughput in windows file transfers.
Same setup but with the old switch I get 10MB/s indicating 100Mbit. Both tests with the same cabling.
This would tell me theres nothing wrong with the cables.

Cables are going through walls and between 2 floors, thus not so easily changed.

Edit 2: At some ports of the switch i got as low as 30ish KB/sec

 

[Fardringle]

If you connected a computer directly to the cable that normally is between the two switches, and the connection worked properly on that cable, then yes it would make me lean toward the second switch itself as the cause of the problem.

In Wireshark, I usually just set it up to capture, transfer a bunch of data, then look to see if there are any data errors reported by the program after it runs for a few minutes.

 

[Tobis]

Im getting alot of red text on black background:
eg: Header checksum: 0x0000 [incorrect, should be 0xd796 (maybe caused by "IP checksum offload"?)]
Edit: seems that this would be common. Never mind me....

It seems I'm still at a loss when it comes to packets analyzing. I have no idea what to do next...

 

[Tobis]

Sooo I got a new switch, this time not a netgear. Even though its worked nicely for a few years, maybe 3 ish, I dont think it should lose gigabit functionality like it seem to have done. Id rather it stop working at all rather than report gigabit connections and only deliver 100Mbit.
My new switch is a Linksys. Its just as pretty.

Thanks for all the help and support during my time in need.

 

[robmurphy]

Please remember when taking traces that frames that fail the frame checksum will dropped by the NIC. What this means is that Wireshark is no good for checking to frames that have failed because of bad wiring. The PC simply does not know about packets that fail the checksum on the Ethernet frame.

To monitor errors like this, i.e. wiring problems, you need a good managed switch that will give counts of Ethernet packets with errors.

Rob.

 

[Tobis]

I'm sure you're right but wouldn't that incur a price increase most home networkers aren't ready to accept?

Im not sure at what price point you get managed switches, have some product examples?
My Linksys was 295 SEK (~40 $US).

 

[robmurphy]

I did not mean that you should get a managed switch, just that checking for frame errors would not help you as its not something the home user can normally do. You can use Wireshark to check for missing packets. This is quite simple with UDP, but more trouble with TCP as it will re-transmit. The TCP checksum being wrong is quite common on for gigabit Ethernet links as most gigabit NICs (including the ones on the motherboard) will calculate the TCP checksum.

I would suggest using the router and the switch as before with a short cable. If you get gigabit transfer rates like that, then try it using the same switch, router and PCs but with the long cables. Test each like this. I appreciate its a pain, but that will effectively test the cabling. If some cables show a a big drop in speed you know there is fault with those cables.

The other thing to be watch for is long patch leads. By long I mean over 10 metres. Any cables with hand crimped RJ45 plugs should also be avoided.

For long cable runs there really is no alternative to solid core cable between 2 RJ45 sockets, and then good ready made patch leads from the sockets to the PC, router, or switch.

Rob.