Speed drops when using UTP.

[jopc3]

Entschuldiging fur meine posting in English, aber meine Sprache in Deutch is nicht gut genug
fur erklaren mein problem. Viellicht kan jemand ubersetzen.

I had some problems with a very low training speed for my Fritz 7340.
After a lot of testing, I think I have reduced the problem to the
UTP.
As long as I do not use UTP (That means, no UTP connected into
the Fritz), the modem connects with a speed of 16Mbit, just as at always
did.

As soon as I connect an UTP cable to the Friitz, the number of errors
raises, and as soon as I reboot the modem, the new speed
is 5Mbit. I tried multiple UTP cables.

Any sugestions??

 

[chked]

Where is the UTP cable connected? Do you use the cable for the DSL signal or do you just connect a PC via ethernet?

 

[jopc3]

I think I have traced it down to some problems with my good-old 3Com switch.
As long as do not use that switch, the modem trains in at a good speed.
Using the switch with only the modem connected: no problem.
As soon as I connect other systems to the switch: problems with speed
an errors.
All those tests using the same cable, and modem at the same location.

So my conclusion: Do not the that switch anymore.

Next question: Whats a good choice for a new switch, and suppose
I want to upgrade my cables to Cat6, Should I buy STP or UTP?

 

[RalfFriedl]

Using the switch with only the modem connected: no problem.
As soon as I connect other systems to the switch: problems with speed
an errors.

So my conclusion: Do not the that switch anymore.

Why is your conclusion that the switch is the problem? Have you omitted that you have no problem when you connect the other systems directly to the box?
Is your cable really UTP, or is it shielded? If it it shielded, you could try an unshielded cable.

 

[jopc3]

My previous post was indeed a little short. Here is what I did:

I connect the Fritz to the switch, with nothing else connected to the switch : Ok
Then I connect my NAS to the switch too (So Fritz and NAS connected to switch): Errors
Then I remove the NAS from the switch, and connect my PC to the switch (So Fritz and PC connected to switch): Errors.

NAS connected to Fritz, without switch OK.

NAS, Fritz, PC all connected to some spare 7170 (Used as a switch): OK

Fritz connected to 7170, 7170 connected to 3COM: OK, as long as not other devices are connected to the 3COM. As soon as
another device is connected to the 3COM: Errors.
Fritz connected to 7170, 7170 not connected to anything: OK.

So whatever combination I did: as long as I am not using the 3COM switch with more then 1 device, its OK.

Every test is executed by a reboot of the modem (power disconnect, and
executed twice).

My cable it UTP, and none of the cables had a metal jacket.

Wim

 

[RalfFriedl]

This is really strange. According to your description, there is no electrical connection between the 3COM switch and the Fritz 7340. It seems that the switch sends data that "disturbs" the 7340. Maybe it tries STP as soon as two devices are connected, although that shouldn't slow the modem part of the 7340.

I use cheap switches from TP-Link and didn't have a problem with them.

Is there a reason why you want to upgrade to CAT6?

 

[jopc3]

Yes, I agree that everything sounds strange. But at least I am rid of my error
rate of more then 150K errors per seconds and a modem training speed
of 5MBit instead of 17MBit.

No specific reason of upgrading to Cat6, only that I have a strange habbit that I
upgrade equipment seldom, but once I start, I upgrade in large bunches.

You have any preference for UTP versus STP? In my situation, cables are not very
well concealed and separated. Maybe that should give some
preference to STP??

Wim

 

[RalfFriedl]

I normally use shielded cables, but as long as your old cables work I would just keep them.

 

[jopc3]

I do not really understand what caused all this trouble, but a new switch solved the
problem. Thanks for all the effort helping me.