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Thursday, July 19, 2012

Crossover vs Patch.

What is the difference between a Crossover Cable and a Patch Cable?
A "Patch Cable" connects a computer to a Hub or patch panel.
A "Crossover Cable" connects two computers together without a Hub.

There are benefits to both. Using a "Crossover Cable" is an inexpensive way to connect two computers together that are in the same room. However, this is limited to exactly 2 systems. A third system could not be introduced to your network. Using a "Patch Cable" for each pc and a HUB to connect the patch cables together makes for a reliable, multi user environment. Your network is limited to the size of your hub only. Multiple hubs can be connected with "Crossover Cables".

Before we see how to make a crossover cable, let's start with a regular cat5 patch cable.
There isn't much difference between a crossover cable and a regular patch cable.
Below is what a patch cable looks like.
Here's what a crossover cable looks like. Notice only one end has changed. Wires 1 and 3 have been transposed, and 2 and 6 have also been transposed.

What's the Difference between crossover and straight thru cables?
The wiring in a crossover and straight thru (or standard patch cable) is different. They have different purposes in different LAN configurations. Crossover cables almost always have the word Crossover written on the cable itself. If they do not, odds are it's a Straight Thru cable. (aka Regular Patch cable.)

How to tell Straight Thru vs. Crossover:
The main way to tell would be to hold up the ends together, the wiring is the same on both sides, its Straight Thru, if one side has opposite wiring, its a Crossover.

If you do not have the correct type of cable in the correct place, your LAN will NOT work.

Where to use a Crossover, and Where to use a Straight Thru:
All Ethernet cables going out of the router use standard ports. (1-4, etc)
All connections going TO a computer mean into the Ethernet card in the computer.
From a Router or Bridge to a Hub:
Crossover into standard port. (i.e. port 4).
*From a Router or Bridge to a Hub 2:
Straight Thru into Uplink port.
From a Router or Bridge to a Computer:
Straight Thru into Ethernet card on PC.
From Hub to Computer:
Straight Thru

* If you want to use your uplink port on your Hub, it is usually possible to use a Straight Thru from the Router to the Uplink port of your Hub.
What is the difference between a Router and a Bridge? How do I know which is which?
The configuration of a Router and a Bridge is different, Bridge setups will always have static IP's set to the machines, but not the Bridge itself, Router will always have a static IP on the router, but the Machines can be setup with either NAT Ip's (Internal and protected), or Static Ip's. See Section 3 in table of contents for information on the setup in your machine.
A Router is, simply put, a small computer, which provides the Internet connection from the DSL Line, to your computer. The Router can be configured to do many things, Such as running NAT (Network Address Translation), running firewalls, allowing ports in. It has its own IP address And can be connected to Remotely via Telnet. Some Routers come with their own GUI software for easy configuration. (see Router manual).
A bridge is more along the lines of merely a DSL Modem. It does not have its own IP address, and cannot be configured. All settings are set in the computer, or computers that are hooked up to the Bridge.
Small device with multiple ports on the back, ranging from 4 to 8, to 16, and much higher. Ethernet card Hardware that must be installed on your computer for DSL to work. Can be purchased at any local computer store.
Routers are installed by Covad and provided by Aplus.Net, Routers have their own IP Address and usually contain a built in firewall or other security options of some sort.
A bridge basically acts as a Bridge between the ISP and the Computer hooked up to the Bridge. A Bridge does not have its own IP address, and basically is just a modem, that connects your machine to the Internet, it has no security features.