Troubleshooting a fiber connection

[OMaraSTO]

Anyone know about problems with fiber?

One of our regional offices is having problems with connectivity, on cabling which had been installed by a partner company. The office down there can see back to head office fine, and works well, but there is a second building across the car park that is having the problems (on the same network).
The link between the two buildings is:
Switch feeds Cat5 to a D-Link DFE 855 adapter, which outputs some kind of fiber cable, which runs across to the other building where another D-Link DFE855 converts it back to Cat5. When I tested, I timed the login:
Plugged directly into the switch: 1min 7 sec
Plugged in via the fiber (crossover cable from laptop into the D-Link adapter at the far end) 2min 40 sec!!!!!

Anyone got any suggestions they would be most appreciated.
Thanks

Steve

 

[Jtodd]

Doesn't sound like a cabling problem. But, try cleaning the fiber properly at both ends. Could be an issue with your cross over cable.
What's the distance on the fiber? Also, is the media converter 100Mps or 10Mps? If it's 100, get better patch cords, best you can spring for. Patch cords are typically the weakest link. Other than that, from the provided info, I'd say its a network config issue of some type.

Justin T. Clausen
Physical Layer Implementation
California State University, Monterey Bay

 

[jimbopalmer]

I have a FAQ over in the ethernet forum explaining how duplex is not negotiated in a fiber connection, be VERY sure you understand how duplex is controlled at every step. All the converters and everything have to agree.

the FDE 855 will try to negotiate the copper side full or half duplex, getting all the settings correct will take some doing, but it should work.

http://dlink.com/products/?pid=140

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

 

[OMaraSTO]

Thanks for your replies.

JTodd - I tried a pre-made crossover cable I had with me, then also just in case I made my own crossover cable on site and tried that, both the same results, so I don't think it is that.
Distance on the fiber I would guess somewhere between 100 and 200 metres. The media converters are 100Mps.

Jimbo - Thanks for that, your FAQ was good reading I rated it 10! Also I didn't know there was a separate ethernet forum so that's also handy to know. When I was down on site, everything appeared to auto-detect duplex at 100Mps. The switch was auto-detect but had indicator LEDs for the ports showing full duplex, the D-Link adapters didn't seem to have any adjustable settings on them at all, and the laptop on the other end was on auto-detect and checking the connection properties displayed 100Mps full duplex. It's very puzzling!