Cable Installation, Cabling, Washington D.C.

Ethernet Crossover Cable Basics

24 Jan 2018

Cable Installation, Cabling, Washington D.C.The crossover cable connects two Ethernet network devices to each other. They were invented for temporarily supporting host-to-host networking when a network router or another intermediary device is not available. Although crossover cables appear the same as a standard straight-through (patch) Ethernet cable, their internal wiring structures are different.



Straight Through vs. Crossover


A straight-through cable is used for connecting two different kinds of devices, such as a network switch to a computer. In contrast, a crossover cable is for connecting two devices that are identical.


The straight-through cable’s ends can be wired in any manner, but both ends must be identical. This is different from the crossover cable’s internal wiring, which reverses the signals for receiving and transmitting. The first and third wires and the second and sixth wires are crossed.


High-quality Ethernet crossover cables have special markings which allow users to distinguish them from straight-through cables. They are often red in color and the word "crossover" will appear on its casing and packaging.



Crossover Cable Needs


Crossover cables came into use during the 1990s and 2000s because the most common types of Ethernet were unable to support direct cable connections between hosts. Intended for using specific wires for both receiving and transmitting signals, the original and Fast Ethernet standards required the communication of two endpoints through an intermediary device to avoid conflicts.


The Ethernet feature MDI-X has auto-detection for the prevention of signal conflicts, enabling the Ethernet interface to automatically determine and negotiate the expected signaling convention of the device at the other end of the cable. The majority of home broadband routers and Gigabit Ethernet adopted MDI-X.


As a result, crossover cables are only necessary for the connection of two Ethernet client devices if they are not configured for Gigabit Ethernet. Nowadays, Ethernet devices are compatible with crossover cables because they can automatically detect them.



Ethernet Crossover Cables Usage


Crossover cable usage should be limited to direct network connections. When a user tries connecting a computer to an antiquated router or network switch via a crossover cable rather than a standard cable, the link can be prevented from working.



Progressive Office Cabling


Founded in 1986, Progressive Office’s success has been a direct result of years of commitment to seeking solutions on behalf of our clients in the Washington, D.C. and New York City areas. Efficiently working together, Progressive Office teams get cabling installed and operating as fast as possible while minimizing disruption and downtime. Call our toll free number (800) 614-4560 today.

Network Cabling, Data Cabling

Bad Connectors will Kill your Network

3 Jul 2014

A client was having serious connectivity and network issues. It was a very small business with just a few computers. But as they were working, a couple of the machines were losing their connection to the Internet. The problems and symptoms had been going on for over a year. They would lose Internet connection and they figured out that if they unplugged and replugged the network cable that the connectivity would usually come back. But sometimes, they would have to unplug and plug a few times to get connected. As you could imagine, this was incredibly frustrating for them.


Fortunately, we found and fixed the problem very quickly.


When network connections are flaky we always first look at the cabling and then the hardware and software. And since this was a network-wide problem, we had a strong feeling that they either had a cabling issue or a bad network switch.


In Figure 1, we took a photo of the connector that was going into the modem/router. If you look closely, you can see that the sleeve ends just short of the connector. This is so wrong. The sleeve needs to go inside of the connector so that it provides support and strain-relief to the 4 twisted pairs of wires. The wires would get bent at 90 degrees which changes the impedance and properties of the signal. Figure 2 is the inside of one of the wallplates. As you can see, the wires are untwisted and then punched into the slots for each of the 4-pairs. But they are untwisted too much.There should be no slack in between the sleeve and the connections. So, again, this will greatly reduce the effectiveness of the data transmission.


All cable connections and wallplates were checked and fixed. We cut off the bad connectors and recrimped on new ones. And we reterminated the wallplate. Since then, they have had 100% uptime on the Internet Service.


Are you having network cabling issues? Call 202-462-4290 or click here to contact us.