Lan cable test

[Anthony5]

Since I'm installing a new Ethernet switch, and didn't know what cable goes where, I bought a cable tester and started testing.

I have some cables, which worked well previously, for example to the media player in the living room, but give strange test results.

At the end of the hub the test lights run from 1 - 8, but at the media player end they run something like 3-6-1-4-5-2-7-8.

Something to worry about?

[tariq786]

Just use straight cables. Switches automatically will take care.

[Anthony5]

Just use straight cables. Switches automatically will take care.

What you mean with use straight cable?

The cable I'm testing is installed already and is tested at the wall socket.

There is only 1 out of 24 cables that give this result.

So it should read 1-4-5-2-7-8-3-6

OK, checked on the wiki and it is correct wired cross over.

Is there an advantage for the cross over?

Edited August 19, 2015 by Anthony5

[RichCor]

In the early days of Ethernet they used to designate equipment as either Data Terminating Equipment (DTE) -or- Data Communications Equipment (DCE)

The RJ45 port pins were wired so a 'straight' cable would allow DTE TX (transmit/send) pin pair to directly send data on wires that would connect to the DCE RX (receive) pins on the connecting equipment on the other side. The physical ports on the equipment were different to allow a straight 8P8C cable to be utilized.

In Ethernet TP (Twisted Pair) cabling, one set of twisted pair wires is designated as a TX (transmit/send) channel, and another pair designated as a RX (receive) channel.

If all Ethernet Ports are wired the same, then a device sending data on TX pins of an Ethernet port, out on a 'straight' cable, connect to the next device would also connect to the TX pins of that Ethernet port (and no data would be conveyed).

So, either the equipment manufacturer can designate the Ethernet port as DTE (wired accordingly) so TX pins using a 8P8C 'straight-cable' connected to DCE equipment RX pins (and data flows as desired), or the cable can be made to 'cross-over' in the case of DTE to DTE -or- DCE to DCE connected equipment.

Complicating all this is not always knowing if the equipment you're working with is physically wired as a DTE or DCE specification.

Complicating this even further is the added smart ports utilizing MDI-X auto-detect that attempt to 'sense' the correct wiring necessary and 'electronically' make the TX-RX RX-TX connections.

Background (from RJ45 Cable Wiring: T-568-B Straight-through & Crossover RJ-45 cabling)

The straight-through cables are used when connecting Data Terminating Equipment (DTE) to Data Communications Equipment (DCE), such as computers and routers to modems (gateways) or hubs (Ethernet Switches). The cross-over cables are used when connecting DTE to DTE, or DCE to DCE equipment; such as computer to computer, computer to router; or gateway to hub connections. The DTE equipment terminates the signal, while DCE equipment do not.

Short Answer: Someone made up the cable and decided it should be, or needed to be, a cross-over cable.

As mentioned, when MDI-X auto-detect is in effect a straight-cable is a straight-cable is a cross-over cable is a straight-cable. Doesn't make any difference (that is until the MDI-X auto-detect get's into a snit and keeps switching back and forth. Sorry, that wasn't really a short answer.

Edited August 19, 2015 by RichCor

[Anthony5]

In the early days of Ethernet they used to designate equipment as either Data Terminating Equipment (DTE) -or- Data Communications Equipment (DCE)

The RJ45 port pins were wired so a 'straight' cable would allow DTE TX (transmin/send) pin pair to directly send data on wires that would connect to the DCE RX (receive) pins on the connecting equipment on the other side. The physical ports on the equipment were different to allow a straight 8P8C cable to be utilized.

In Ethernet TP (Twisted Pair) cabling, one set of twisted pair wires is designated as a TX (transmit/send) channel, and another pair designated as a RX (receive) channel.

If all Ethernet Ports are wired the same, then a device sending data on TX pins of an Ethernet port, out on a 'straight' cable, connect to the next device would also connect to the TX pins of that Ethernet port (and no data would be conveyed).

So, either the equipment manufacturer can designate the Ethernet port as DTE (wired accordingly) so TX pins connect with RX pins on a 'straight-cable' connected to DCE equipment, or the cable can be made to 'cross-over' in the case of DTE to DTE connected equipment.

Complicating all this is not always knowing if the equipment you're working with is physically wired as a DTE or DCE specification.

Complicating this further is the added smart ports utilizing MDI-X that attempt to 'sense' the correct wiring necessary and 'electronically' make the TX-RX RX-TX connections.

Background (from RJ45 Cable Wiring: T-568-B Straight-through & Crossover RJ-45 cabling)

The straight-through cables are used when connecting Data Terminating Equipment (DTE) to Data Communications Equipment (DCE), such as computers and routers to modems (gateways) or hubs (Ethernet Switches). The cross-over cables are used when connecting DTE to DTE, or DCE to DCE equipment; such as computer to computer, computer to router; or gateway to hub connections. The DTE equipment terminates the signal, while DCE equipment do not.

Short Answer: Someone made up the cable and decided it should be, or needed to be, a cross-over cable.

As mentioned, when MDI-X auto-detect is in effect a straight-cable is a straight-cable is a cross-over cable is a straight-cable. Doesn't make any difference (that is until the MDI-X auto-detect get's into a snit and keeps switching back and forth. Sorry, that wasn't really a short answer.

So in fact it probably doesn't harm, but if set straight would be better,

I haven't opened the wall socket yet, but do you know if it easily can be adjusted or do I need special tool for it?

The socket is from Clipsal/Schneider.

[RichCor]

Usually trades people will wire all the jacks the same (T568- color scheme throughout an install. Either do nothing, or wire it the same as all the other jacks in the house.

The colored wired can usually be popped up and put back into a new position. The manufacturer usually included a special plastic tool for making sure the wire is deeply seated in scissor-pin connector, but as long as you push the wire down evenly on both sides of the scissor-pin when replacing the wire it should make a permanent-enough type connection.

Edited August 19, 2015 by RichCor

[rakman]

If you have GigE devices, ie switch and computer, it doesn't matter. GigE uses all 4 pairs and is smart, so a cross over or straight cable works.

Not true of 10/100 which uses the first and second pairs and is much more intolerant.

[Anthony5]

So finally got finished marking all the LAN cables so that I know where they lead.

At the switch I have 3 cables in excess which I don't have an idea where they go, wouldn't be a big issue wasn't it that 1 of the cables get the number 6 light flash when I connect the tester.

I think that means that the other end of the cable is connected to something.

I will add that the light No.6 only flash when the powered part of the tester is connected, with the remote part connected no light flash.

Is that correct?

[innerspace]

That is likely a faulty cable looping back.

Yesterday had a similar shock where a tester returned positive on 3 pairs even though the return end wasnt attached, a camera was!

Would chop or recrimp the cables with odd results.

[Anthony5]

That is likely a faulty cable looping back.

Yesterday had a similar shock where a tester returned positive on 3 pairs even though the return end wasnt attached, a camera was!

Would chop or recrimp the cables with odd results.

If a camera is attached it will use only 3 or 4 wires, at least that is the result I get when I attach my tester to a cable connected to a CCTV.

The point is that I have no idea where either of those 3 cables go to,every socket or network appliance in the house has been marked already, but I think the one that has the light No. 6 flash must be connected to something to make this happen.

[RichCor]

When the house was built, what areas were designated for cabling? (Front Gate, Car Port, Portico/Entrance, Kitchen, Wine Cellar, Walk-in Closet, Panic room, Bathroom, Elevator, Observation Tower, Green House, Helipad, Tennis Courts, Swimming Pool, Sauna, Dungeon, Recirculating Salt Water Surf Pool, Mud Bath, Wood & Metal Shop, Machine Gun Turret / Guard Tower, Exercise Room, Racquetball Court, Ice Rink, Recording Studio, Screening Room... )

Did I get all 24 ports?

(I think I forgot to allow one port for Internet IN)

[Anthony5]

When the house was built, what areas were designated for cabling? (Front Gate, Car Port, Portico/Entrance, Kitchen, Wine Cellar, Walk-in Closet, Panic room, Bathroom, Elevator, Observation Tower, Green House, Helipad, Tennis Courts, Swimming Pool, Sauna, Dungeon, Recirculating Salt Water Surf Pool, Mud Bath, Wood & Metal Shop, Machine Gun Turret / Guard Tower, Exercise Room, Racquetball Court, Ice Rink, Recording Studio, Screening Room... )

Did I get all 24 ports?

(I think I forgot to allow one port for Internet IN)

Ever heard about the THAI Mahal?

Or how about 8 CCTV, 3 bedrooms each with a one connection for TV and one for PC,living room with also 2 connections, safe room with connection, alarm system with ethernet port and Patio with one connection for TV and one for laptop, 2 routers and one port for PC and one for server?

I wanted Ethernet in the maids quarters as well, but I couldn't find a switch with 25 ports

Edited August 20, 2015 by Anthony5

[Anthony5]

OK, have been reading up on everything Ethernet cables today and found the reason why this one socket is cross wired.

There is a socket at both sides of that wall, one inside the house and the other outside.

When you connect two Ethernet devices without using a hub you should use cross cable. So I think the intention of the installer was to connect the socket inside with the socket outside, so that no extra cable needed to be pulled from the hub.

Thing however is that outside there is a socket but no cable connected to it.

I have now adjusted the wires at the socket and the outside socket will remain unconnected.

[RichCor]

Yep. Loop-though second connection. Not my favorite thing to see.

A loop-through or passive splitter won't allow three-way conversation between all three nodes (as none of the nodes repeat what it hears).

But as 10/100 Ethernet running on CAT 5/5E has 2 unused wire pairs, wiring convention allows the spare pairs to be used for Power over Ethernet (PoE); two phone lines; or a second 10/100 BASE-TX connection. So the alternative would be to convert the single cable into TWO Ethernet connections by running 2 twisted-pairs of wires to one Ethernet Connector and the other 2 twisted-pairs of wires to a second Ethernet Connector on the Hub/Switch side, while simultaneously wiring the other end to two separate wall jacks (no pass-through, no cross-over). This would allow the connections at the Hub/Switch to keep both wall jack nodes in active communication.

[Anthony5]

Quick question.

I understand that Gigabit Ethernet port is not different from a 100 Mb port.

My server has a Gigabit LAN, so if I connect the server to my 10/100 switch, wouldn't that mean that it could send 100 Mb/sec of data from the server through several ports at the same time anyway because it get fed up to a Gigabit?

[RichCor]

A GbE port will automatically is 'fall back' to 100 Mb/s when 1000 Mb/s negotiations/communications fail.

When connecting a GbE port directly to a 100 Mb/s Device, only 100 Mb/s is possible.

But if a 10/100 Switch also has a GbE 1000 Mb/s port then a GbE File Server could communicate with a GbE Switch at 1000Mb/s and the Switch could then communicate with multiple 100 Mb/s clients. The Switch takes care of the speed conversion.