Wiring

Connectors

RJ45 Jack and Plug Pinout.

Ethernet

The TIA/EIA-568-A specifies two wiring standards for a 8-position modular connector such as RJ45. The two wiring standards, T568A and T568B vary only in the arrangement of the colored pairs. We are using T568B.

Straight-Through Cable Pinout (T568B):

RJ45 Pin #       Wire Color      10Base-T Signal     1000Base-T Signal
                   (T568B)      100Base-TX Signal
   1             White/Orange       Transmit+           BI_DA+
   2             Orange             Transmit-           BI_DA-
   3             White/Green        Receive+            BI_DB+
   4             Blue               Unused              BI_DC+
   5             White/Blue         Unused              BI_DC-
   6             Green              Receive-            BI_DB-
   7             White/Brown        Unused              BI_DD+
   8             Brown              Unused              BI_DD-

Cross Over Cable Pinout (T568B):

RJ45 Pin #     Wire Color         RJ45 Pin #     Wire Color    
 (END 1)                           (END 2)
   1          White/Orange           1          White/Green
   2          Orange                 2          Green
   3          White/Green            3          White/Orange
   4          Blue                   4          White/Brown
   5          White/Blue             5          Brown
   6          Green                  6          Orange
   7          White/Brown            7          Blue
   8          Brown                  8          White/Blue

NOTE: The cross over cable layout is suitable for 1000Base-T operation, all 4 pairs are crossed.

The following diagram shows the Normal use of Crossed and Straight cables:

straight--HUB,SWITCH--crossed--HUB,SWITCH--straight--PC

PC--crossed--PC

NOTE': To avoid the need for Crossed cables many vendors provide UPLINK ports on Hubs or Switches - these are specially designed to allow the use of a STRAIGHT cable when connecting back-to-back Hubs or Switches. Read the manufacturers documentation carefully.