Each LAN Card has an ID number, which is unique number in the world. This id is called MAC address (Media Access Control). IEEE manages the MAC address space. When Company wants to manufacture adapters; it purchases a chunk of the address space for a nominal fee.
Suppose a MAC address is 12-34-56-78-90-AB
Six Hexadecimal Number. 1st 3 Hexadecimal numbers are given from IEEE and are known as the Organizationally Unique Identifier (OUI). Last 3 Hexadecimal numbers are given by manufacturer.
(Now we have got cable and LAN card but how we connect card and cable. We need Connector. There are different connectors for different cable.)
Connectors:
Considering connector or cable, LAN port should be compatible. Connectors for Cables are -
Coaxial Cable:
Thin net – RG-58
Thick net - RG11, RG8 Most use coaxial cable is RG-59 category and connector we use for this cable is BNC
Lets see how to connect connector with coaxial cable
1. Cut the Outer Black Jacket cable half inch
2. Carefully pull back the Shield outside the outer cover
3. Trim back the plastic (usually white) from the inner core cable
4. Push the connector down over the cable end so that the copper core of the coaxial cable sticks out
5. Screw the connector into the end of the cable
Twisted Pair Cable:
For Twisted Pair Cable, we use RJ45connector. RJ means Registered Jack.
There are 8 pins of connector.
1. TX+
2. TX-
3. RX+
4. Unused
5. Unused
6. RX-
7. Unused
8. Unused
7&8 for future use such as PoE but 4&5 always off. that's why its called RJ45.
The positive and negative connectors in the cabling mentioned, form a balanced pair for signals. They typically carry identical signals of opposite polarity, i.e. a HIGH bit may be +5 Volts on the + conductor, and -5 Volts on the - conductor. The corresponding LOW bit would then be -5 Volts on the + conductor, and +5 Volts on the - conductor.
Having such signals of opposite polarity in a twisted pair of wires helps in reducing susceptibility to common-mode noise / EMI. Because the voltage difference between the two conductors for any valid bit is twice the actual signaling voltage, this has the effect of doubling the strength and hence the detection of the signal at the receiving end.
What will be the color combination of cable? Two organizations fixed an international standard for this cabling EIA & TIA. So if we do something should try to follow International rules. EIA/TIA 568 standard builds for Media installation and termination.
EIA/TIA 568A defined color-coding for RJ45 connector is-
1. Green-White
2. Green
3. Orange-White
4. Blue
5. Blue-White
6. Orange
7. Brown-White
8. Brown
EIA/TIA 568B defined color-coding for RJ45 connector is-
1. Orange-White
2. Orange
3. Green-White
4. Blue
5. Blue-White
6. Green
7. Brown-White
8. Brown
Note that it is very important that a single pair be used for pins 3 and 6. If one conductor from one pair is used for pin 3 and a conductor from another pair is used for pin 6, If this is not done the receive data will be split between 2 pairs and performance will degrade.
We have learned cabling in two ways - 568A and 568B. If we match color coding both end of the cable 568A or 568B this is called Straight Through Cable. If one side is 568A and another side is 568B this is called Cross Over Cable.
Now question is that when we will use cross over or straight through cable? If the devices at the both ends are same then we will use cross over cable and if the devices at the both ends are different then we will use straight through cable. (There is another definition we will learn later.)
There is another type of cabling called Roll Over. One side is inverse of another side. Suppose if one side is 568A then another side will be Brown - Brown White – Orange – Blue white – Blue – Orange white – Green – Green white. Roll over cable used for configuration purpose. Suppose any router, manageable switch etc. To connect switch/router it needs to attach a console connector in one side for the console port. That’s why it is sometimes called console cable.
To punch cable with RJ45 Connector, we need a tools called Crimper.
Fiber Optic Connectors:
There are different types of Fiber Connectors.
Most Used Connectors are SC (Subscriber Connector), FC (Fiber Connector), LC (Lucent Connector). But we have no available devices to connect connector with fiber cable. So we buy Fiber Patch Cord (built in connector with few meters fiber).
In this way we use different types of connector in fiber.
We have connected our two PCs with a cross over cable according to EIA/TIA rules via NIC (Network Interface Card).
But out 1st problem arises that these cables can pass only current voltage, not anything else. Then how we will send data?
Think carefully cable is either passing current or not. That means when switch on current passing through cable, when switch off, cable passing nothing. Using this on off activity we can send signal to receiver. If we let the current on is 1 and off is 0 then receiver will get combination of 0 and 1.
For an example (This is not actual value), PC1 wants to send "How are you" to PC2. If we let
How are you = 1010
then PC1 will switch on and voltage starts to pass, receiver will get 1. Switch off voltage is not passing, receiver will get 0. Again switch on and voltage starts to pass, receiver will get 1. Switch off voltage is not passing, receiver will get 0. So receiver will get 1010 combination. So PC2 will understand, PC1 sent "How are you"
Isn't that nice? Now we have to convert all data into 0 and 1 anyhow but in a unique way so that 01 combination never match with one another. Then we can send data using current signal.
That's why ASCII Code was created. We will know little about ASCII.
to continue reading click on NextBut out 1st problem arises that these cables can pass only current voltage, not anything else. Then how we will send data?
Think carefully cable is either passing current or not. That means when switch on current passing through cable, when switch off, cable passing nothing. Using this on off activity we can send signal to receiver. If we let the current on is 1 and off is 0 then receiver will get combination of 0 and 1.
For an example (This is not actual value), PC1 wants to send "How are you" to PC2. If we let
How are you = 1010
then PC1 will switch on and voltage starts to pass, receiver will get 1. Switch off voltage is not passing, receiver will get 0. Again switch on and voltage starts to pass, receiver will get 1. Switch off voltage is not passing, receiver will get 0. So receiver will get 1010 combination. So PC2 will understand, PC1 sent "How are you"
Isn't that nice? Now we have to convert all data into 0 and 1 anyhow but in a unique way so that 01 combination never match with one another. Then we can send data using current signal.
That's why ASCII Code was created. We will know little about ASCII.
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