Ethernet Link LED is lit but cannot ping

[selimsl]

Hi!

I have a device (named ETG100) which has an Ethernet port and it is connected to my PC through a Ethernet switch. When I ping the IP address of the ETG100, ETG100 relies. So everything is ok. But if I put my ETG100 to a different place where almost 30 m far from Ethernet switch and use another Ethernet cable(a longer cable), the Link LED of the ETG100 is lit but I can not ping the IP address of the ETG100. I couldnt understand why I can not ping, I checked the cable and it seems ok and Link LED is lit... Does anyone has a idea?

Thanks...

 

[jimbopalmer]

Two ideas

1) The link light indicates connection in one direction only, BOTH ends need a link light before you can ping.

2) It is possible the 'different cable' is not using twisted pairs for pins 1 & 2 and pins 3 & 6, be sure you are using EIA 568 B standard color coding

http://en.wikipedia.org/wiki/TIA/EIA-568-B

If you do not use pairs, 'link' can work, it is DC, but AC-like data may fail.

I tried to remain child-like, all I acheived was childish.

 

[selimsl]

Link lights at both ends are lit, but I used Straight Ethernet Cable. Should I have used Crossover cable? By the way I didn't care color codes.
You said: If you do not use pairs, 'link' can work, it is DC, but AC-like data may fail.
What is DC and AC?

Thanks...

 

[jimbopalmer]

http://en.wikipedia.org/wiki/Direct_current

http://en.wikipedia.org/wiki/Alternating_current

(the signal is really pulsating current, I think)

If you need a cross over cable, you should not get link lights.

Is this the ETG100 you have?

http://www2.schneider-electric.co.j...ef74925713e002ed4b6/$FILE/ETG100セットアップガイド.pdf

I tried to remain child-like, all I acheived was childish.

 

[selimsl]

Yes, ETG100 is a device from Schneider Electric. I did the cable again , complied standard color coding and it is working now. So, when I use pairs the cable start working properly.

Thanks for help

 

[StaplesMan]

I have seen this problem many times where cables are not created correctly. The longer the cable is more and more cross talk you get.

Have you ever talked on the your analog phone line and hear someone else in the background on another line? This is cross talk. And this is caused because cables are not twisted tight enough. One wire of one pare is two close to another wire of another pare and induction takes place (longer the run of closelness more induction) and the data (analog or digital) will hop over to the other wire.

see..

http://en.wikipedia.org/wiki/Crosstalk_(electronics)

This same thing happens with network cables. This is why you have cat3, cat5, cat6 and so on. Each one is a step higher in the number of twists per inch.

The data that is transmitted on two wires at one time but 180 degrees out of phase. So when one wire goes HI (1) the other one goes Low (0). Then these two wires are twisted very tightly around each other. This way if there is any interference it will appear on both wires at the same time (very important) because when this interference come into the network card at the other end it will do a match on the voltage levels of the cable and the spike (interference) will be eliminated. This is called balanced.

see..

http://en.wikipedia.org/wiki/Balanced_line

Serial ports (com port), Printer Port (parallel), SCSI, and IDE (PATA) on your computer are unbalanced but USB, FireWire, SAS (Serial attached SCSI), and SATA. are all balanced. This is why they perform faster then there predecessors.

Hope this helps to clarify matters!


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