T-568a Crossover same as T-568b??

[gasgasgreg]

T-568a Crossover same as T-568b?? Confused here.
Tended to wire 568a straight but when crossover I have wired
1 : 3
2 : 6
3 : 1
4 : 4
5 : 5
6 : 2
7 : 7
8 : 8
I have seen many diagrams that match this.
However looking recently I read & more often
1 : 3
2 : 6
3 : 1
4 : 7
5 : 8
6 : 2
7 : 4
8 : 5
My cheap tester matches this in each case.
These are not the same, are they??

My network is 99% fine have lots of switches etc, camera's & PC's.

But recently one camera & AP behaving oddly, works mostly but some strange behaviour depending on where on my network they are.
It is fine in some locations but not in others.
I have PC's & cameras in those other locations & they are 100& fine so really confused.

It would be understandable if they just did not work but might be fine to 6 hours then fail.

Too varied to explain right now but could someone advise if/what the crossover situation is as I have above.

Thanks I/A

 

[bill001g]

First there should not be a need for any form of crossover cable. All ports have had auto mdi/mdix for many years.

The concept of crossover does not apply to gigabit cables. They transmit and receive on all four pairs at the same time from both ends. Almost seems magic when you look at all the issues 10/100 has with transmit and receive pairs.

10/100 only uses the pairs 1,2 and 3,6 the other wires are ignored and can technically be connected anyway you want. Gigabit seems to tolerate cables with uncommon connetions, as long as the wires from the same pair stay together. Still using any cable that is not a straight cable on a gigabit port increases your odds the port will drop to 100mbit. The auto detection of the speed is confused by cable that are not straight through but it surprisingly works fine even on cross cables most the time.

 

[gasgasgreg]

Hi,

Many thank for you reply,
This is what I always thought & never had a problem before.
I have perhaps 10 switches dotted around my network. one main modem-router to a 20 port switch then off to others if different directions so not too much of a bottleneck. There might be the odd old 10/100 but not in any central or route in the network.

However I have a new camera that was behaving oddly, would loose stream after minutes or some hours. If moved to different part of network it would be fine for days. They have replaced 3 times.
From the same switch that failed the camera I have PC's & other equipment all been working fine for years.
Also not exactly the same place but close I have a new AP (Again I have a few of the same)
Works in one place & not another.
The really odd thing is connecting via WiFi to this AP, phones, tablets, chromebooks would all work fine, full internet & network access.
Try to connect a windows laptop (tried two) and they would not connect. "cannot connect to this network" Tried everything over hours.
In desperation I put one of my crossover cable between the switches and the AP would then let window pc connect.
None of that makes any sense so I was just trying to think if somewhere I have one of my cross over cables
I do have some 30 & 40 meter runs so not easy to switch & swap or even test.

I also had some intermittant disconncetions/pause with a wireless bridge but that could be a multitude of things but begining to feel there is just something very occassionaly upsetting the whole LAN.

Factory rest everything & regular restarts

Hence clutching at straws for any ideas.