Crossover Cable Vs Ethernet Cable: What’s The Difference？

Crossover Cable vs Ethernet Cable: What's the Difference?

Crossover Cable vs Ethernet Cable

Ethernet patch cable is normally divided into crossover cable and straight through cable by different networking applications. Straight through cable is a type of common network cable and is widely used, while crossover cable is a special Ethernet cable type. These cables are essential not only in traditional IT infrastructure but also in modern industrial settings, including facilities for Lithium Battery Manufacturing where reliable network connectivity is crucial for monitoring production lines and quality control systems. Therefore, when doing a comparison of crossover cable vs Ethernet cable, it is actually the comparison between Ethernet crossover cable and straight through cable (referred as Ethernet cable in this post).

One thing to keep in mind: most modern networking equipment now includes a feature called Auto-MDI/MDI-X, which can automatically detect the cable type and adjust accordingly. This has made crossover cables far less common in everyday use. Still, understanding the difference remains important when working with older equipment or specialized industrial systems.

Crossover Cable vs Ethernet Cable: What Is An Ethernet Cable?

Ethernet cable/straight through cable such as Cat5, Cat5e and Cat6 cable, etc. is a type of twisted pair cable primarily used in local area networks to connect two different types of devices such as in the following situations:

• A computer to a cable/DSL modem's LAN port

• A computer to a switch/hub's normal port

• A router's WAN port to a cable/DSL modem's LAN port

• A router's LAN port to a switch/hub's uplink port

• Connect 2 switches/hubs with one of them using an uplink port and the other one using normal port

• The common thread here is that straight-through cables connect different types of devices. Network engineers refer to this as connecting an MDI port to an MDI-X port. Computers and routers have MDI ports, while switches and hubs have MDI-X ports. The MDI-X port already has an internal crossover, so an external crossover cable is not needed.

Actually, when it comes to crossover cable vs. Ethernet cable, it is inevitable to think of their wiring system. As we know, T568A and T568B are two standards recognized by ANSI, TIA and EIA for wiring Ethernet cables. They differ in the order of the 8 cable colors. For T568A, the color order of the 8 pins are white, green, white orange, blue, white blue, orange, white brown, and brown from pin 1 to pin 8 respectively. While, in T568B wiring standard, there are two color order exchanges compared with T568A, pin 1 in exchange for Pin 3 and pin 2 in exchange for Pin 6.

Complete Pinout Reference

For those who need to crimp their own cables, here is the full pin assignment for both standards:

T568A Standard:

T568B Standard:

Pins 4, 5, 7, and 8 are unused for data in Fast Ethernet but may carry PoE power. In Gigabit Ethernet, all four pairs are used for bidirectional data transmission.

Both standards perform identically. T568B is more common in North America and commercial installations. T568A is often required for U.S. government projects and is more popular in residential wiring. The key is to stay consistent throughout your installation.

Straight through cable uses the same wiring standard on both ends. That is, both ends (connector A and connector B) use T568A wiring standard or both ends use T568B wiring standard with the same color.

This works because the MDI-X port on the switch or hub performs the crossover internally. When a computer (MDI) sends data on pins 1 and 2, the switch receives it on pins 1 and 2 but routes it internally to its receive circuit. No wire swap is needed in the cable itself.

Crossover Cable vs Ethernet Cable: What Is A Crossover Cable?

Crossover cable such as Cat5, Cat5e crossover cable, etc. is a type of twisted pair cable used to connect two devices of the same type such as "DTE to DTE" or "DCE to DCE" in the following situations:

• One computer to another computer

• One switch to another switch connecting a normal port on both sides

• One hub to another hub connecting a normal port on both sides

• A router's LAN port to a switch/hub's normal port

In all these cases, you are connecting two MDI ports together or two MDI-X ports together. Neither side performs an internal crossover, so the cable must swap the transmit and receive pairs.

Are Crossover Cables Still Necessary Today?

For equipment made after 2005 or so, usually not.

Auto-MDI/MDI-X is a feature built into the Ethernet port's PHY chip. It detects what type of device is on the other end and adjusts the pin assignment automatically. HP engineers invented this technology in 1998, and it became part of the Gigabit Ethernet standard (IEEE 802.3ab) in 1999.

Here is what this means in practice:

• All Gigabit Ethernet devices support Auto-MDI/MDI-X. It is mandatory in the standard.
• Most Fast Ethernet (10/100 Mbps) devices made after 2000 also have this feature.
• Only one end of the link needs to support it. If either device can auto-detect, the connection will work regardless of cable type.

There are still some cases where crossover cables are needed:

• Very old networking equipment from the late 1990s or earlier
• Industrial PLCs, SCADA controllers, and embedded systems with fixed port configurations
• Situations where auto-negotiation has been manually disabled
• Lab environments for network certification training

If you are unsure, try a straight-through cable first. On modern equipment, it will almost always work.

Different from the straight-through Ethernet cable, crossover network cable uses two different wiring standards on both ends (connector A and connector B). One end uses the T568A wiring standard, and the other end uses the T568B wiring standard. The following shows the crossover cable wiring diagram:

A Note on Gigabit Ethernet

Gigabit Ethernet (1000BASE-T) works differently from Fast Ethernet. It uses all four wire pairs, and each pair transmits data in both directions at the same time. There is no dedicated transmit or receive pair at the physical layer.

Because of this design, Gigabit devices can adapt to either straight-through or crossover cables even without Auto-MDI/MDI-X. The PHY chip figures out the wire mapping during link establishment. So if both devices are Gigabit-capable, the cable type rarely matters.

Conclusion

In short, the similarity of crossover cable vs Ethernet cable comparison is obvious. Both Ethernet cable and crossover cable abide by T568A and T568B wiring standards with 8 different color pins on each side of the connector. While the former one connects two different types of devices to each other such as "a computer to a switch" and the latter one connects two devices of the same type to each other such as "one computer to another computer".