Now days, LAN card has intelligence, so that both cables can work.
They have a feature on lots of switches and hubs etc called "auto-mdix" or "auto mdi/mdix", that is the new thing where it doesn’t matter what kind of cable you use, it will just auto detect the proper connection type no matter which cable you use.
The cable can be categorized as Cat 5, Cat 5e, and Cat 6 UTP cable. Cat 5 UTP cable can support 10/100 Mbps Ethernet network, whereas Cat 5e and Cat 6 UTP cable can support Ethernet network running at 10/100/1000 Mbps. You might hear about Cat 3 UTP cable, it's not popular anymore since it can only support 10 Mbps Ethernet network.
Straight and crossover cable can be Cat3, Cat 5, Cat 5e or Cat 6 UTP cable, the only difference is each type will have different wire arrangement in the cable for serving different purposes.
Ethernet network cables are straight and crossover cable. This Ethernet network cable is made of 4 pair high performance cable that consists of twisted pair conductors that used for data transmission. Both end of cable is called RJ45 connector.
There are two types of network cables commonly used in PC networks - Straight-through and cross-over.
Straight Cable
Usually use straight cable to connect different type of devices. This type of cable will be used most of the time and can be used to:
1) Connect a computer to a switch/hub's normal port.
2) Connect a computer to a cable/DSL modem's LAN port.
3) Connect a router's WAN port to a cable/DSL modem's LAN port.
4) Connect a router's LAN port to a switch/hub's uplink port. (Normally used for expanding network)
5) Connect two switches/hubs with one of the switch/hub using an uplink port and the other one using normal port.
If you need to check how straight cable looks like, it's easy. Both sides (side A and side B) of cable have wire arrangement with same color.
Crossover Cable
Sometimes you will use crossover cable, it's usually used to connect same type of devices. A crossover cable can be used to:
1) Connect two computers directly.
2) Connect a router's LAN port to a switch/hub's normal port. (Normally used for expanding network)
3) Connect two switches/hubs by using normal port in both switches/hubs.
In you need to check how crossover cable looks like, both side (side A and side B) of cable have wire arrangement with following different color.
This cable (either straight cable or cross cable) has total 8 wires (or we can say lines), i.e. four twisted pairs (4x2=8) with different color codes. Right now just forget about color codes. It doesn’t matter what color is given to the cable (but there is a standard).
In straight cable connectivity is like as follows
RJ451 Connected to RJ452
Pin1------------------------------------- Pin1
Pin2------------------------------------- Pin2
Pin3------------------------------------- Pin3
Pin4------------------------------------- Pin4
Pin5------------------------------------- Pin5
Pin6------------------------------------- Pin6
Pin7------------------------------------- Pin7
Pin8------------------------------------- Pin8
In cross cable connectivity is like as follows
RJ451 Connected to RJ452
Pin1------------------------------------- Pin3
Pin2------------------------------------- Pin6
Pin3------------------------------------- Pin1
Pin4------------------------------------- Pin4
Pin5------------------------------------- Pin5
Pin6------------------------------------- Pin2
Pin7------------------------------------- Pin7
Pin8------------------------------------- Pin8
Purpose of this cross cable is RX (receiving terminal) connects to TX (transmitting) of one pc to another PC and vice versa.
As we use two PCs (same devices), straight cable will connect TX to TX and RX to RX of two computers, so cross cable is required. If you use HUB or switch, then straight cable will work because it has internal arrangement like cross cable. So note that use cross cable to connect two similar devices.
A straight cable will not work to connect two computers together.
Crossover used to connect to PCs directly together, also used for connecting networking devices together like Switch to Switch etc.
Straight cables connect two DIFFERENT types of devices. Whereas crossover cables connect two of the SAME type
