Jabbering network port problem

[Mickwish]

I have a single network connection on my home LAN that is occasionally starting to jabber. It's not a particular port on a switch, it is a line wired to a wall plate at one end and a RJ-45 connector at the other. It goes from my office to my shed, and is about 20 meters in total length. It is joined in the middle with an RJ-45 coupler (hard wired).

The jabbering seems to occur randomly - sometimes when the connection is in use (ie when I'm in the middle of something), sometimes when it's apparently idle. The weird thing is the connection lights in the shed never waver, but the connection light on the switch in the office jabbers. No packets get through when this happens. I can stop it simply be unplugging and reseating the RJ-45 connector in the switch in the office, or at the other end. And it also seems to resolve itself as well if I just leave it for a while (never measured how long).

This is a recent problem, it this connection has always worked perfectly previously. Currently, the line is connected via patch cable from the wall plate to a 10/100 switch, and the other end is also connected to a 10/100 switch. I have tried:

- direct connection to a PC NIC in the shed;
- different direct PC NIC connections (different PC, different NICs - tried 10 and 10/100 and 100 only NICs);
- different ports of two different switches in the office;
- a different patch cable from the wall plate.

Have run out of ideas. I don't have access to a hardware line tester. Now I want to see if there are any software tools that will help me identify the source of the jabbering. Anyone have any ideas?

Thanks
Mick

[Gait_Keeper]

I know nothing about jabbering ports....................

where is Vass when you need him?

[DVNT1]

With all you wrote, I don't see anything consistant about the problem. I would suspect it is a specific port on the switch or else a NIC. Sometimes jabbers can be caused by EMI.

How do you know there is jabbering? By light activity or a testing tool?

[Mickwish]

Light activity. very rapid flashing of the connection LED on one switch. But the port doesn't seem to matter. And the network segment on that port becomes unreachable, until the jabbering ceases.

What sort of stuff might causes EMI problems? None of the rest of the LAN has an issue, but this cable does go through parts of the ceiling no other does. And it comes within a few feet of the main power box as well.

Apart from monitors, which are not always on, there are not many sources for EMI in the shed. A fluoro light near the switch, but it's rarely on.

Thanks for the reply DVNT1.

I'll keep this thread posted with more info as I check more.

Cheers
Mick

[DVNT1]

Interesting problem you have Mick.

I' don't have much experience with EMI problems/causes. Although what you describe sounds like EMI to me. The random occurrences could be explained by appliances like a refrigerator, washer, dryer, etc... that only draw high current infrequently.

I would replace the cable with a shield UTP cable, fiber, or run the cable via a different path.

[Mickwish]

Hmm, if I had to do that, might as well run it wireless than reroute the whole cable.

Haven't had so much of a problem the last few days - has only done it once (that I noticed - less traffic since I made all the FAD cows standalone, though).

Will see what happens, then will try to put more traffic back on that cable and see if I can make it jabber more.

It goes in the ceiling almost the whole length of the house, so passes over almost every electrical device in it! If EMI is the culprit I'll priobably never pick what it is...

Thanks again DVNT1.

Cheers
Mick