Linux-Hams archive - May 1997: Re: 100 Mbit Ethernet Problem

Re: 100 Mbit Ethernet Problem

Karl F. Larsen (terhi.victor@logonet.com)
Sun, 4 May 1997 07:11:21 -0600 (MDT)


Hi Tim,
Sounds like your having a lot of fun! What your problem sounds like is a bad
connector and perhaps your 50 ohm termination may not be 50 ohms at 50 MHz.
I assume your loading both ends with with what you hope is the coax
impedance and it is not.

In radio terms "you have rf on your coax shield" which can be bad.

At 12:30 PM 5/4/97 +0000, you wrote:
>OK, now I've seen alot of crazy fixes... but could someone please
>explain this:
>
>I was working on a friend's 100 mbps Fast Ethernet network. One of the
>40' lines we had ran suddenly quit working. So we replaced the cable and
>put new connectors on and it worked. Except it was pinging about 45%
>successful and 0% if you used a larger packet (4K).
>
>By about 1 am, we were desperate. I wound up a couple feet of cable in
>my hands making a small 4" coil. Suddenly packets were flying once
>again. So we taped the cable, let go of it and once again, pings were
>unsuccessful. So we took a donut looking metal piece and wrapped the
>cable around it in a coil fashion. The rate rose to about 75%
>successful. Good enough!!!
>
>There was another line which had been run right next to the original
>cable. Although it worked perfectly, we tried disconnecting it and only
>running one cable at a time. This had no effect.
>
>Any ideas on why this happened ????
>No transmitters were being used at the time. Any ideaS???
>
>Thanks - Tim/kb8eht
>
73, de Karl aka k5di

Karl F. Larsen Box 74, Mesilla Park, NM 88047 (505) 524-3303
axuts.wcsmq@pharmacia.com bmxkpm.ufivbw@musiclink.se