Gigabit Ethernet as slow as 10/100

sobamonster42 · Jun 28, 2013

I have a network setup where I have a desktop running Windows Vista 32bit connected by a short LAN cable to my router (Aztech GR7000) which has gigabit ports, which connects to a 20 meter Cat5e cable to my 5port switch (Zyxel GS-105B) which also supports gigabit, which then connects to my desktop running Windows 7 64bit with a 10m Cat5e cable. Both desktops have gigabit ports.

So far the transfer rates im getting regardless of file size is 90+mbps (10MB/s) which is no where near gigabit speed and seems like its capping out at 10/100 speeds. I will be getting 200mbps fibre broadband soon (currently 100mbps) and I don't want the network to slow my access.

Does anyone know how to overcome this limitation? Is it a hardware or windows problem? Thanks

dbhosttexas · Jul 1, 2013

Check your speed / duplex settings in the network interface drivers on both desktops... You may be auto negotiating to 100Mbps.

Another possibility is slow disks on one or the other machine. Say for example if you have a PATA 100 hard disk on one of those hosts, you will never be able to get full gigabit file transfers unless the files are small enough to be cached in RAM...

sobamonster42 · Jul 16, 2013

dbhosttexas :

Hi I recently upgraded to 200mbps as mentioned before and sure enough there is a bottleneck on my network. When running speedtest.net on my desktop connected directly to my router (Aztech GR7000) i get 160mbps down and 94 mbps up. However on my desktop connected to the gigabit switch (Zyxel GS-105B) i get a maximum of 94mbps down and 80mbps up which is no different than before the 200mbps upgrade. My network setup for the desktop connected to the switch is as follows:
Fiber modem --> Aztech GR7000 --> 20m Cat5e cable --> Zyxel GS-105B --> 15m Cat5e cable --> Desktop

The desktop connected directly to the router has a 7200RPM SATA2 HDD.
The desktop connected to the switch uses a Corsair 128GB SSD as its main drive.
I don't think the harddisks in this case is a limiting factor

dbhosttexas · Jul 16, 2013

I don't see anything about you saying you checked and insured the settings on speed / duplex are configured and verified. MANY switches / NICs will fail to autonegotiate at the fastest settings, you need to manually set it up. ASSUMING YOU DID THAT, If you are getting proper speed directly connected to the router, bypassing the switch, but you get serious reductions in performance with the switch, I would suspect the switch, the cables you are using with the switch. If possible test using the LAN cables that you use with the switch, to the router directly instead, try to rule out the switch, if you cannot, then replace the switch. I have no experience with Zyxel, but have seen fair to good things about their stuff, but any MFG can ship flaky hardware. It happens all the time.

sobamonster42 · Jul 16, 2013

dbhosttexas :

I checked the speed/duplex settings and even set it to 10mbps half duplex to verify if changing the settings will affect performance. I then switched it back to 1gbps full duplex and turned off all the energy saving features but the speed I get is still capped at 95mbps. Switches have no settings page on them right?

velosteraptor · Jul 16, 2013

Switches do have network pages. unless you are referring to a "hub"?

sobamonster42 · Jul 17, 2013

velosteraptor :

I tested each part of the connection and found that it is the 20m Cat5e cable that connects the router to the switch that is unable to handle 1gbps connections. I tried a 20m Cat6 cable connected directly to the router and found no problems. This means I have to reinstall a new Cat6 cable :/ rather troublesome. I hope this is the only bottleneck on my network!

Hawkeye22 · Jul 17, 2013

The security in your router may be slowing it down. Stuff like SPI (stateful packet inspection) on the router can slow down throughput. Try connecting your modem directly to your PC and see if there is a difference. Hopefully you don't have one of those combo modem/routers.

dbhosttexas · Jul 17, 2013

sobamonster42 :

Not a plain Jane "dumb" switch, which that little desktop switch is. Have you tried bypassing the switch with one of the LAN cables used to connect router to switch, and switch to PC so you can eliminate the switch, or one of the cables as the culprit?

dbhosttexas · Jul 17, 2013

D'oh! You said TP-Link switch didn't you? Make certain your devices that are connecting to it do not use Jumbo Frames (Google Jumbo Frames and your OS). TP Link is notorious for not supporting Jumbo Frames with their switches. It will kick you down to 10/100 no matter what if it is enabled on your device.

One of the reasons I opted for TrendNET instead of TP-Link...

sobamonster42 · Jul 18, 2013

Hawkeye22 :

is SPI an important feature on the router? I can get higher speeds above 100mbps when i connect a laptop directly to the router but i get a max of 94mbps when connected to the switch. refer to my post above for a visual idea of my setup

sobamonster42 · Jul 18, 2013

dbhosttexas :

Yes I connected a laptop directly to the 20m Cat5e cable that runs from the router to the switch and got a max of 94mbps (10/100 speed). I intend to change the cable to Cat6, hope it solves my problems.

What are jumbo frames? My switch is a Zyxel brand, not TPLink. But the new router im planning to buy (Archer C7) is by TPLink. So I should disable this feature when i buy my new router?

Hawkeye22 · Jul 18, 2013

sobamonster42 :

It is an important feature that most routers have, but some routers use a better implementation that doesn't slow traffic as much.

dbhosttexas · Jul 18, 2013

sobamonster42 :

Jumbo frames are oversized packets, used by certain equipment, and OSes to assist in gigabit plus communications. However not all gigabit hardware supports them. Sorry, I thought you said your switch was TP-Link for some reason. Not sure about Zyxel switches. Okay so let me get this straight, you use one particular cable straight to the router, and you are limited to 94Mbps, you use a different cable and your speed increases? Pretty good indicator that your cable is at fault here. The bigger question is why though. Is this running parallel, and close to power wires? That can cause inductive interference, which will slow down communications quite a bit...

Hawkeye22 · Jul 18, 2013

dbhosttexas makes a good point. EMI/RFI can cause problems. power lines, motors (like air conditioners and stuff), and other electronics in proximity to the network cable can cause issues. If you can't reroute the cabling, you will need to go with shielded twisted pair cabling instead of unshielded cabling. Shielded cabling costs a little more, but can handle EMI/RFI much better.

sobamonster42 · Jul 18, 2013

dbhosttexas :

Hawkeye22 :

they converge and run parallel for only 30cm. but i dont believe there is signal interference unless 1 cable is better shielded than the other. Another possibility is that one cable is Cat6 while the other is Cat5e, that being said a 20m Cat5e cable should be able to handle gigabit ethernet. What I read on wiki is below 100m Cat5/5e will have a 10mbps limitation. not sure what length for 1gbps limit. in fact if any cable should have interference it should be the Cat6 cable, it runs parallel with a analogue TV signal cable for the full 20m.

dbhosttexas · Jul 18, 2013

Not sure what to tell you. When you connect the cat5e cable, your speed drops... Do you have access to a similar length category 6 cable to test with?

Mind you, properly terminated, category 5e cable is rated up to gigabit speed at 100m. Not 10Mbps. Whatever wiki entry you saw that told you that was radically wrong.

sobamonster42 · Jul 20, 2013

dbhosttexas :

it was definitely the cable. just bought a 20m Cat7 cable and got 180mbps down 85mbps up. with a 20m Cat6 as i posted earlier i got 140mbps down. 1m Cat5e cable I got 140mbps down. so seems like length does matter. Pun intended lol

Gigabit Ethernet as slow as 10/100

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