Network wiring problem - weird one!

[tony sayer]

What switches have that built in?.....

[Ron Lowe]

Certainly the cicso ones do.

I can't really say about others. You'd need to check their data sheets.

[Tim S]

"Ron Lowe" coughed up some electrons that declared:

And Extreme Networks (much underrated IMO - very nice to work with)

Cheers

Tim

[Bob Eager]

But does the PC at the other end of the circuit?

[dennis]

Only one end needs to.

[The Natural Philosopher]

As far as the electricals go, it's pairs in the right pairs of terminals, so will work just as well.

AS I said before' all that matters is a pair on 1 nd 2, a pair on 3 and

6, a pair on 4 and 5 and a pair on 7 and 8. Which way round they are, or what colors they use, are actually not a problem.

In fact for ethernet up to 100Mbps,only 3 and 6, and 4 and 5 need be connected at all..

[Bob Eager]

Ah...yes!

[Andy Wade]

Thanks to all who replied on this. The next question then is when/where/why would you use a managed switch?

[John Rumm]

When you want more control that you get with an unmanged one. You can enforce better security (i.e. limiting traffic between certain parts of a network to only those parts, regardless of any tricks people may play to try to spoof the switch). You can actively manage traffic better - allocating more bandwidth to certain applications or reserving a certain quality of service. You usually get SNMP monitoring so you can check on the state and performance of attached kit. Posher ones will have support for virtual lans and things like spanning tree protocol.

[Andy Wade]

Noted - thanks.

[Ron Lowe]

Completely WRONG ( (copyright) TNP )

ITYM 1+2, and 3+6.

How can you have managed all these years, getting it wrong every single time? :-)

- Ron

[The Natural Philosopher]

Ah, you may be right..after the first time when I actually taught some people who did wiring how to do it, I employed them to do it every time.

And promptly forgot 90%.

[John Rumm]

With RJ45 the pin numbers on the socket match those of the plug (unlike say the BT phone plug!). However, that is not usually particularly useful information since the presentation of the IDC terminals will vary in layout depending on both brand and type of socket. So you need to follow the colour code on the particular socket.

[John Rumm]

Another very good site for pinouts of just about everything:

[Dave Plowman (News)]

[PCPaul]

Looks like it from his diagram. As long as the colours each end of a cable and on both ends of the faceplates are the same it should 'work', although using the proper EIA/TIA 568 A or B colour coding will give you much better range and lower crosstalk figures.

None of the cables in the system should be 'crossover' types, although the majority of routers now have MDI/MDIX ports that can automatically cope with straight or crossover anyway.

If a network engineer did the faceplates and the cables came from work then both of those should be OK. That leaves the cables.

Cat-5 is sturdy enough, but probably a bit lighter than your sparks was used to, especially since they are almost certainly solid core. Putting too tight bends or bending them too often could get you snapped cores. But again, you say the network tester said it was OK. (Aside: if anybody needs one, try this - it's simple but it works well and costs almost nothing: )

So if all the wiring is OK, that leaves... nothing.

With the laptop plugged into a faceplate, can you ping the routers IP address?

Is the four way faceplate fully wired into the router, or do you just have a couple of cables? Are you sure the right sockets are connected all the way back to the router?

When you plug the laptop in, does the 'link light' come on (usually a green led on the rj45 socket on the laptop, and another on the router?)

[John Weston]

Except for the problem already identified in this thread...

That type of tester will only tell if you have random wires on the same pins at each end, not whether you have use the correct wires from the twisted pairs onto the correct socket pins. It indicats all is fine if the cable is basic muti-wire alarm cable instead of Cat5

The place I used to work was wired using Cat5. (As a foreigner by a local BT installer.) He had installed the pairs 1-2, 3-4, 5-6 & 7-8, which would have been fine on your tester. It worked until we started using 100Mbps and auto speed detect devices...

[Dave Liquorice]

It is almost certainly the limitations of such cheap testers that caused the confusion about this install in the first place. The correct pins are wired to the correct pins but with the same wiring error at each end. Thus the signals between the two sockets are not being sent over the twisted pairs of wires which is essential for the connection to work.

I hope that the "installation engineer" that did this work has learnt something from his reliance on his cheap tester...

[PCPaul]

The perils of answering before reading the whole thread...

Oh well, I do use a TDR for work testing and only use the cheapo for home jobs.. and I've never had the same colour swapping problem that this one turned out to be. Found plenty of bad connections and shorts with a cheapy tester, which TBH in a circuit that 'used to work' is all that's likely to happen.

I have seen some cables with such small dabs of such faint colours that it was hard to figure out which was which without following it back to the twisted bits, though.