Straight cables are used to connect PCs or other equipment to a HUB or Switch. If your connection is PC to PC or HUB to HUB you MUST use a Crossed cable.
The following cable description is for the wiring of BOTH ends (RJ45 Male connectors) with your category 5 wiring colors (TIA/EIA 568A or 568B though the example uses 568B colors).
|Pin No.||conductor color||Name|
|1||white and orange||TX_D1+|
|3||white and green||RX_D2+|
|5||white and blue||BI_D3- **|
|7||white and brown||BI_D4+ **|
We use BLUE for 100baseT straight cables.
Wires marked ** are ABSOLUTELY NECESSARY for 100Base-T4 networks - used when any combination of category 3/4/5 cables are present, when using 1000base-T (GigE) and MAY be required for Power-over-Ethernet (PoE) - see below.
Wires marked ** are not essential for 100Base-TX (using cat 5/5e ONLY cables) and CAN be used for other purposes, for example, telephony but, and our LAN plus Telephony article before you wire your entire neighbourhood for surround sound.
The Power-over-Ethernet spec (802.3af) allows three schemes where power may be supplied. Two of these schemes use pairs 4,5 and 7,8 (marked ** in above table) for power (called Midspan PSE and Alternative B or Mode B), one scheme uses ONLY pairs 1,2 and 3,6 (Endpoint PSE, Alternative A or Mode A) for both signals and power. Depending on which scheme you use pairs 4,5 and 7,8 may be required.
All our wiring is now done to the 100base-T4 spec which you can use with 10baseT networks - but NOT the other way around.