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Let's put into practiceUnderstanding cablesIf you want to connect two computers each other, you could simply use a CROSSOVER cable. There are two kind of network cables: straight-through cables and crossover cables. When you connect 2 computers each other, each of them can receive data or send data. But...ethernet cards are not reversed each other. Each computer has the *SAME* ethernet card. Any ethernet card has some wires that receive data and some other wires that send data. In the example in the next picture, wire 1 is for sending data whereas wire 2 is for receiving data. If you are using a straight-through cable you get something like this:
B RECEIVES data from A by using the *SENDING* wire (1)!!! Not really possible!
--------- ---------
| |1-)------ DOES NOT WORK! ------------(-1| |
| A |2-( )-2| B |
--------- ---------
192.168.1.1 192.168.1.2
B SENDS data to A by using the *RECEIVING* wire (2)!!! Not really possible!
--------- ---------
| |1-) (-1| |
| A |2-(------ DOES NOT WORK! ------------)-2| B |
--------- ---------
192.168.1.1 192.168.1.2
(picture 7)
Notice that wire 1 is sending data and wire 2 is receiving data in both computers. That's impossible, so to connect 2 computers each other you have to use a crossover cable:
A SENDS data to B and B receives data from A through the *RECEIVING* wires so this WORKS!!!
--------- ---------
| |1-)))------\ (-1| |
| A |2-( \--------)))-2| B |
--------- ---------
192.168.1.1 192.168.1.2
B SENDS data to A and A receives data from B through the *RECEIVING* wires so this WORKS!!!
--------- ---------
| |1-) /--------(((-1| |
| A |2-(((-----/ )-2| B |
--------- ---------
192.168.1.1 192.168.1.2
(picture 8)
or, better:
--------- ---------
| |1-)---------\ /-------(-1| |
| A | X | B |
| |2-(---------/ \-------)-2| |
--------- ---------
192.168.1.1 192.168.1.2
(picture 9)
Picture 9 shows how a crossover cable works. If you want to connect more computers, you need a STRAIGHT-THROUGH cable, because you are using a HUB. HUBs have a kind of reversed 'ethernet cards'
so you have to use a straight-through ethernet cable. Hubs' 'ethernet cards' have sockets to plug the cable in. Such sockets are called ports. Things get confused if you have to connect two hubs (or switches)
each other. In this case you have to use a crossover cable unless hubs have an uplink port (MDI port). An MDI (Medium Dependent Interface) port also called Uplink port is used to connect two hubs without having
to use a crossover cable. You have to think so: when you connect two 'things' that are equal each other you have to use a crossover cable; when you connect two things that are NOT equal, you have to use a straight-through
cable:
1) ethernet card to ethernet card -> crossover 2) hub NORMAL PORT to hub NORMAL PORT -> crossover 3) hub UPLINK PORT to hub UPLINK PORT -> crossover 4) ethernet card to hub UPLINK PORT -> crossover 5) ethernet card to ROUTER PORT -> straight-through 6) ethernet card to hub NORMAL PORT -> straight-through 7) hub NORMAL PORT to hub UPLINK PORT -> straight-through 8) ACCESS POINT to hub NORMAL PORT -> straight-throughAs a rule of thumb, take a look at the green led of the connected port. A turned off led means that the connected port is not receiving/sending data. A green led means that the port is operational. A Flashing green led means that the port is sending/receiving data. A cat 5 ethernet cable is a standard cable used to connect network devices. A typical cat 5 ethernet cable has a RJ45 plug for each end. Ethernet cables, 802.3 cables, 10/100 cables, 10baseT cables, 100baseT cables, refer to the same thing. <--- Index --->
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