Junior Network Engineer seeks help

cheeky_guy

Hi im 24, i graduated college last May 05 and ive just landed a job as a Junior Cisco Network Engineer in a government house. Its my second week on the job and ive been ordered to fix a problem and im having some problems doing so and i would like to solve it on my own (so to speak).

Basically this building is still using coaxial cabling which is throwing up problems the whole time. The client at the moment has no network connection from his PC. Also he is assigned IP's staticaly which have disappeared.
The office i am currently working in has the two coxial cabels coming from the wall, into a t-connector and then into the PC. I hooked these two cables up to the fluke machine and it gave off readings of 59 resistance which i think is ok. However when the two cabels are plugged into the t-connector and then plugged into the fluke they drop resistance by at least half.
I have tried new connectors and cabels but nothing seems to be working. Im not even sure if this is why the network connection is gone but id at least like to find out how to bring the resistance back up to its full power.

Any help really appreciated...

axer

cheeky_guy wrote:

Also he is assigned IP's staticaly which have disappeared.

You mean there is an IP address associated with his MAC address- right?
The office i am currently working in has the two coxial cabels coming from the wall, into a t-connector and then into the PC. I hooked these two cables up to the fluke machine and it gave off readings of 59 resistance which i think is ok. However when the two cabels are plugged into the t-connector and then plugged into the fluke they drop resistance by at least half. [/QUOTE]Could that be because you have just reduced the resistance by using both wires? i.e. two paths to the same destination - that would half the resistance.

Gotta go now quick....sorry.

MunsterCycling

Have you checked to make sure the link isn't broken / disconnected?

CrazySka

DHCP problem??

Static M.e.

Havent used Coax in years.. but if you try some of the standard tests

run Ipconfig/all and see what you get.
Does it say Cable Connected or Disconnected?

Maints

Have you tried assigning the static IP, netmask, etc again ?

Paul.

DemoniK

haven't seen co-ax in years..

Official term is 10-base-2. Should help in googling...

Anyway,
10-base-2 is notorious for being a bit finicky. Many things can go wrong, and usually show up as 1 PC not being able to connect or all.

I wouldn't worry about the resistance you're measuring. If this was at fault it would be pulling down more than one PC. Besides, if you're testing the cable in isolation you're forgetting a key ingredient in 10-base-2 which is the 50ohm terminator.

First question - are the cables you mention coming out from the wall, or are they plugged into the wall. If they are coming out of the wall, it makes it more complicated. But, if they are plugged into the wall, does anyone else get affected if you plug them out? The reason I ask, is that the wall plate has the ability to link the 2 across if no cables are inserted. If no-one is affected we could probably rule out the faceplate - otherwise you might consider replacing it.

Next thing to check is the terminations for the overall line....
10-base-2 is essentially a 185m wire with a 50ohm terminators at either end. The T-piece allows you to "Tap" off a PC from that line. So first thing to check is the terminators. I remember a long time ago, that a good tip is to ensure one of the terminators is grounded terminator - in particular if you are approaching maximum amount of PCs.

Which brings me to next thing to check. For the 185m line, you can only tap off 30 clients before a repeater is needed. The repeater could be faulty, non-existant, etc. Worth checking..

Next if you are in a large office you may need more than 185m in which case the network is split into multiple segments. Again each must be no more than 185m long, and have <30 clients (unless using repeaters). Each segment is usually connected by a switch.

Try taking a working PC from a different segment and putting into the point that your problem PC connects to the network. If you have problems with that PC it must be the cables, faceplate, terminators...

Once you're happy that the problem is the computer, the first thing is try another network card. If the card is a combo card, i.e. it has more than just the co-ax connector you may need to set the interface to use.

If you've managed to get past all that - then it's a software or network configuration problem which requires more info, i.e. OS, Network Card, run ipconfig /all, etc.

RikD.

snipe3000

emm...... what he said ^^

JohnnieM

snipe3000 wrote:

emm...... what he said ^^

laugh