2 Switches = Slow Network? 1 MByte/Sec speed max!!! ???

[sday]

1 MByte/Sec speed max!!! ???

I'm stumped. I have a DGL-4100 Dlink gaming router and a DIR655 DLink N router. Both Gigabit switches. I'm using the DGL-4100 as just a switch, DHCP turned off and I'm not using the WAN side. I have a cable running between the two switches. And 1 computer connected to each switch. When I transfer between the computers I get 1MB/sec transfer rate. If I connect another computer to either switch, I can transfer at around 20-30MB/sec as long as I don't leave one switch. If I take out one switch and connect a computer to the end of the cable that was running between the switches I get great speed.

I've checked all the cables and have determined that the speed loss is when 2 switches are connected. Any idea? I've tried turning off SPI thinking maybe one of the switches was getting busy watching the traffic. I tried turning QoS ON/OFF, no change.

All computers say I'm connected at 1Gbps.

Totally mystified.

Thanks for any input
-Steve

[johnwill]

Me too, I can't imagine what the issue is. Other than the cable or perhaps an electrical grounding issue, it's a mystery.

[sday]

That's what I kept thinking so I made sure I could get the performance on each cable. Using the same power source. What I've found is that the cable connecting the two switches is part of the problem. It's the longest run, but of the same quality as the other cabling. It's about 60-80 feet and when I disconnect a switch and connect a computer, I only get 100MBit connectivity. (the cable does not run by any power source) However, I still get about 9 MByte transfer on that cable going through only 1 switch. (Which sounds about right for 100MBit) When I remove the computer and reconnect the switch I'm back down to 1 MByte. Same cabling, same power source. All other cabling I'm using has been testing for performance and they are all capable of 20-30MBytes a second.

Thanks for weighing in on the problem though.

-Steve

[johnwill]

I'd have to be there to tinker with this one.

I'd be forced to try another cable of the same length, perhaps the connections on the cable are not good? Did you re-do the connectors?

[sday]

Yes I did. The fact that I only get 100MBit on that length makes me wonder about the cable, but it's still strange that the switches communicate about 10 times slower than a PC over the same cable.

I'm using Cat 5e. Should I try something else. Is Cat6 better suited to Gigabit ethernet?

My 802.11g is communicating about twice as fast with my server in the basement as when I disable the wireless and plug in the wire going through the two switches.

-Steve

[johnwill]

In the past, I've had issues with power and grounding issues at remote locations with Ethernet. I used to do a lot of work on Wall St., and those old buildings have lots of power issues. We regularly fought issues like this.

OTOH, you have to be VERY careful to make sure the wiring is proper on the connectors. CAT5e is fully specified for gigabit Ethernet, and I use it here successfully with no issues. I have one cable run that's over 100 feet, and it runs at full speed.

I'd make 100% sure that the cable is wired exactly like this at both ends. CAT5 Cable Wiring Diagram Note that you want to be using the 568-B Wiring for normal connections.

[sday]

At first glance at my connectors again I thought you hit it dead on. As it turns out it is wired exactly as the link you provided. (thanks for that) Looks like that's not it. So I guess it's one of the following:
1. grounding issue
2. dirty power
3. Bad cable, but seems odd I get much better speed if I bypass one switch and plug a machine directly into the same end that was going into the second switch.
4. Maybe 1 of these DLink switch/routers doesn't like being linked.

Both switches are being powered on the same phase of the incoming 220 in the house.

Next thing to try maybe is to take the laptop and 2nd switch down into the basement, try a different shorter cable and see if the problem goes away.

Thanks again for the input.
-Steve

[johnwill]

You could also power them from the same outlet and try a shorter cable, then try the longer cable and see if there's any difference. With a good cable, you should be able to connect up to 300 feet away without any change in performance.