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How to Setup an RJ45 Pinout?

How to Setup an RJ45 Pinout?

Brief Introduction:

As one of the most commonly used networking cables, Ethernet cables are mainly employed to interconnect wired network devices. The most common types of Ethernet cables used to connect networking devices are Cat 5e, Cat 6, Cat 6a, Cat 7 and STP/UTP cables.

Usually, an Ethernet cable is terminated using a modular 8 position, 8 contact connector (8P8C connector), often called Registered Jack 45 or RJ45 connector. The way of connecting the RJ45 connector to Ethernet cables differs according to the type of cable.

RJ45 Pinout:

The RJ45 connector is a modular 8P8C connector used for terminating Cat5, Cat5e, Cat6, and Cat7 twisted-pair cables. RJ45 pinout is a specific wire arrangement that illustrates how the wires of Ethernet cables are terminated. RJ45 connectors have multiple pinout options, including straight-through, rollover, crossover, loopback, and T1.

Out of these pinouts, straight-through is the most commonly used type, which is used for connecting a computer with the network. The other types of pinouts are used for specific network applications. In straight-through pinout, there are two different standards: T568A and T568B, recognized by EIA, TIA, and ANSI.

Wiring Standards :

Before understanding the RJ45 pinout, it is important to learn about the difference between straight-through, crossover, and rollover wiring standards and the use of these cables. The pinout schemes of these three wiring standards are as follows:

1. Straight-Through

The wiring on both ends of the cable is the same in this type of standard. Pin 1 to 8 of connector A is connected to Pin 1 to 8 of connector B directly. These types of cables are used for connecting a host to the client. For instance, a straight-through Cat5e patch cable is used to connect printers, computers, and other network devices to hub or router switches. Straight-through cables can be terminated through T568A or T568B wiring standards. The RJ45 pinout for straight-through Ethernet cables is:

  • Pin 1: Transmit + (White and green)
  • Pin 2: Transmit – (Green)
  • Pin 3: Receive + (White and orange)
  • Pin 4: Blue
  • Pin 5: White and blue
  • Pin 6: Receive – (Orange)
  • Pin 7: White and brown
  • Pin 8: Brown

2. Crossover

Crossover cables are almost similar to straight-through, with the only difference in RX and TX lines. These lines are crossed with each other, which means Pin 1 of connector A is connected to Pin 3 on connector B, while Pin 2 is connected to Pin 6.

Usually, crossover cables are terminated with one end using the T568A standard, and the other end of the cable is terminated with T568B. These cables are used for connecting two similar cables to each other, such as connecting two computers, two hubs or switches with each other. Using crossover cables, one can connect two host devices directly. RJ45 pinout for crossover Ethernet cables:

  • Pin 1: White and green wire, connected to Pin 3
  • Pin 2: Green wire, connected to Pin 6
  • Pin 3: White and orange, connected to Pin 1
  • Pin 4: Blue, connected to Pin 4
  • Pin 5: White and blue, connected to Pin 5
  • Pin 6: Orange, connected to Pin 2
  • Pin 7: White and brown, connected to Pin 7
  • Pin8: Brown, connected to Pin 8

3. Rollover

In a rollover cable, the RJ45 pinouts are completely reversed. Pin 1 of connector A is connected to Pin 8 of connector B, and Pin 2 is connected to Pin 7, and so on. Rollover cables cannot be used in computer networks. These cables are called host cables and are commonly used to connect a device console port for making a programming change to the device. Unlike other cables, rollover cables are used for creating an interface between devices.

 

Cabling Standards:

Ethernet cables include four pairs of twisted wires coded in four different colors. The four colors usually are green, blue, brown, and orange. Each pair of wires includes a solid color and white stripes. There are two different cabling standards in the telecommunication industry for RJ45 pinouts: T568A and T568B.

T5868A is commonly used in the United States and Asia, while T568B is used commonly in the UK and Europe. The two different cabling standards explain how the four pairs of wires are connected on the connector. Both cabling schemes have different color conventions.

The difference between T568A and T568B is:

Usually, an Ethernet cable is terminated using a modular 8 position, 8 contact connector (8P8C connector), often called Registered Jack 45 or RJ45 connector. The way of connecting the RJ45 connector to Ethernet cables differs according to the type of cable.

T568A

T568B

White Green (Receive +)

White Orange (Transmit +)

Green (Receive -)

Orange (transmit -)

White Orange (Transmit +)

White Green (Receive +)

Blue

Blue

White Blue

White Blue

Orange (Transmit –)

Green (Receive -)

White Brown

White Brown

Brown

Brown

When comparing T568A and T568B wiring configurations visually, one can observe that the pin positions of orange and green cable pairs are swapped. Pin 1 on T568A is white-green, and Pin 2 is green, while on T568B cable, Pin 1 is white orange, and Pin 2 is orange.

How to Setup RJ45 Pinout for T568A and T568B:

Choosing one standard over the other depends greatly on the network configuration. The advantage of choosing T568B over T568A is that the T568B configuration is backward compatible with USOC schemes, and it can accommodate current as well as future network demands.

When working with the existing network, it is essential to continue with the current configuration when using straight-through Ethernet cables. If the configuration is unknown, one can find it by testing the continuity of cables. Mixing different configurations will impact the data transfer because the colored and stripped wires will not match in the case of different configurations. In some cases, mixing two different configurations is necessary when connecting components with the T568A configuration are connected to the T568B network. Here, a crossover cable would be required to prevent data loss.

The RJ45 pinout standard specifies two wiring configurations while configuring RJ45 cables. While T568A and T568B standards are almost similar, the T568B standard is used commonly for data applications. The decision of choosing between T568A and T568B depends on current wiring, jack usage, and personal preference. For connecting a T568A device with T568B, one can use a crossover cable.

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