Networking Basics Lesson 005: T568A and T568B

T568A and T568B

Wiring standards for twisted pair cables with RJ45 connectors.

Why is it important to understand the T568A and T568B standards?

To have the ability to create straight through cables and crossover cables for connecting different types of network devices.

Who were the T568A and T568B standards created by?

The Telecommunications Industry Association (TIA).

What do the T568A and T568B standards specify?

The order of the eight wires inside of twisted pair cables when crimped inside of an RJ45 connector.

What is the key difference in the T568A and T568B standards?

The arrangement of the green and orange interior wire pairs.

What does each of the four pairs of wires in a twisted pair cable consist of?

A solid color, and a striped color.

What colors of wires can be seen when looking at the internals of a twisted pair cable with an RJ45 connector type?

Green, white-green, orange, white-orange, blue, white-blue, brown and white-brown.

What is the pin-out for the T568A standard?

White-green, green, white-orange, blue, white-blue, orange, white-brown, and brown.

What kind of standard is the T568A and where is it typically used?

An older standard that is typically used in government installations or if use is mandated by contract.

What is the pin-out for the T568B standard?

White-orange, orange, white-green, blue, white-blue, green, white-brown, and brown.

Where is the T568B standard twisted pair cable typically used and where is it found?

In commercial and residential installations and is found in most modern Ethernet network installations.

Straight-Through Cables

Same wiring standard on both ends (T568A-T568A or T568B-T568B), to connect different device types.

What devices do straight-through cables usually connect?

Computers to a switch, a router to a modem, or a switch to a router.

Which is more commonly used, straigh-through cables or crossover cables?

Straight-through cables.

Data Terminal Equipment (DTE)

Refers to devices that act as a source or destination of data inside of a communication network.

What does DTE equipment do?

They initiate or terminate the communications of a network.

What is considered the endpoints of network connections?

DTE equipment.

What are examples of DTE equipment?

Computers, printers, and routers.

What are DTEs responsible for?

Signal conversion, clocking, and managing data transfer rates.

Data Communications Equipment (DCE)

Refers to devices that provide the necessary signaling and control to establish, maintain, and terminate a communication link.

What are examples of DCE?

Modems, network switches, channel service units (CSU) and data service units (DSU).

What does DCE do?

Act as an intermediary between two DTE devices, to ensure proper synchronization and data flow.

DTE to DCE

Data Terminal Equipment to Data Communications Equipment.

Why is it important to use DCEs to connect DTEs together?

Because of the pin configuration.

What is important to consider when using DCEs to connect DTEs together?

The pin layout must be the same on both ends of the cables in the RJ45 connectors.

Crossover Cables

Uses T568A on one end of the cable and T568B on the other end of the cable, mixing two standards to connect similar devices.

What are crossover cables used for?

When connecting two of the same devices to each other, two computers, two switches, or two routers.

Describe the pin layout of a crossover cable.

The transmit pins on one device (pins 1 and 2) are connected to the receive pins on the other device (pins 3 and 6) to ensure that proper communication occurs.