Trick to getting 100Mbps?



New Member
I was talking to a person who owns a local computer shop about networking cables. They had said that there is a "trick" to getting 100Mbps on Cat5 cabling. This seems a little odd that you just MIGHT get 100mbps if you are lucky at connecting the heads. Why wouldn't you always get 100Mbps if all the wires are connected right? Is this true that there is a trick to it, or are they just pulling a quick one trying to get me to pay for them to do it?



New Member
There is no "trick". I think what he is referring to is the required wire mapping necessary for 100Mb. I would need to refer to a document filed away somewhere to make sure I have the right pin-to-pin mapping to give you. If you need it let me know and I'll see if I can find it.

This wire mapping issue may seem trivial to some but you'd be suprised to find how many people don't have their cable wired correctly. The reason is because this "incorrect" wire mapping is not a problem for 10Mb networks so I think this is where the so called "trick" comes into play.

Hope this helps.


New Member
If I'm not mistaken, the cabling should be pinned: 1 white/orange
2 orange/white
3 white/green
4 blue/white
5 white/blue
6 green/white
7 white/brown
8 brown/white


New Member
This is the EIA/TIA Standard T568A
Plug (looking at connector with the tab on the bottom.
Standard EIA/TIA T568A
(also called ISDN, perviously called EIA)

Both ends for One end for
Pin regular cable crossover cable Pin
=== ============= =============== ===
/--T3 1 White/Green White/Orange 1
Pair 3 \--R3 2 Green Orange 2
/-----------T2 3 White/Orange White/Green 3
/ /-R1 4 Blue White/Blue 4
pair 2 \ \-T1 5 White/Blue Blue 5
\-----------R2 6 Orange Green 6
/--T4 7 White/Brown Brown 7
Pair 4 \--R4 8 Brown White/Brown 8
Lord Murkyl

Lord Murkyl

New Member
jred is correct in his pin wiring
The transmit and receive pairs are pins 1,2 and 3,6.

The color normally follows this convention:
1 white orange
2 orange
3 white green
4 blue
5 white blue
6 green
7 white brown
8 brown

The reason you have to have the 1,2 and the 3,6 connected correctly is due to the way signals are sent over the wire. 10BT and 100BT are differentialy encoded, which means that there is a + and a - for the transmit and a + and a - for the receive. By twisting the + and the - for each transmit and receive pair, you can cancel out common mode errors between the two lines to get a better signal.

You can find more information about common mode errors on the net. Just do a search on AltaVista or something.
Lord Murkyl

Lord Murkyl

New Member
Oh, I forgot to mention that you should use CAT5 certified crimp connectors. They have better NEXT (near end cross talk) and SNR (signal to noise ratio).


New Member
What is average transfer rate of 100Mbit network betweem Windows NT 4 server and Windows 98 on Pentium 200 to Pentium II 450?

My network gets about 25 seconds to copy 100M file from NT 4 to Windows 98. I managed to get up to 15 seconds a while back but I don't know what I did to get that speed. Now, my network is again 25 seconds on 100M file.

Thanks in advance.

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