CHAPTER 9

CHAPTER 9

Ethernet is can be found in layer 1 and layer 2 or the Physical layer 1 and Data Link layer2 in the OSI model. The Data Link layer is divided into two sub layer the Logical Link Control (LLC) and  Media Access Control (MAC). The LLC is in the upper portion of Data Link sub layer and the IEEE describes LLC as 802.2 that communicates up to the upper layers which is the inter action of the hardware and the software it acts as a driver of the NIC (Network Interface Card). The LLC is the one responsible for transmitting and communicating to the upper layers which is in the hardware portion and the one who transmit data into media access control going to the lower layer which is the physical.

                The Media Access Control (MAC) is in the lower portion in the Data Link sub layer. The IEEE describes MAC address as 802.3.

                In the world of networking every device was connected in the same shared network, e.g. Local Area Network, Wide Area Network, Wireless network.

All computers are connected with each other but the confusing question is how could you identify that this message or data is for you.? Since the signal is sent to every device that is connected to a network. In the OSI model layer 2 in Data Link layer specifically the lower part of the sub layers the (MAC) Media Access Control takes place and will answer this question.

Media Access Control address is a unique identifier that assists and help to determine between the source and the destination in an Ethernet network, regardless of what type or name of Ethernet use as long as it was an Ethernet, from MAC going to its lower layer which is the physical their role is for identifying and naming for each device type.

What is the process of creating MAC address? How?

The Institute of Electrical and Electronic Engineers (IEEE) enforced the rules of requiring all vendors that sells Ethernet devices to register with IEEE, and then the IEEE will assign a unique 3-byte code the (OUI) Organizational Unique Identifier.

(e.g.) 00 60 2F

The vendor also create their 3-byte code             

(e.g.) 3A 07 BC

And combine them together that will result the MAC address (00-60-2F-3A-07-BC). The MAC is now created then the vendor will now burn the MAC address into the chip ROM (Random Access Memory) in the NIC (Network Interface Card) that makes the MAC address permanently unique and cannot be change and alter by any software or user, therefore in every NIC (Network Interface Card) that have Ethernet ports contains unique MAC address (Media Access Control) address.

CHAPTER 8

CHAPTER 8

The upper OSI layer protocols such as the Data Link Layer, Network, Transport, Session, Presentation, and Application Layer they prepare data from the human network for transmission to its destination while the physical layer controls how data is placed on the communication media.

The role of OSI physical layer is to encode binary digits that present to Data Link layer frames into signals and to transmit and receive these signals across the physical media such as wireless, copper wire and optical fiber that connect network device.

There are three basic type of network media used for transmitting data such as copper cable, fiber and wireless. Each type of network media have different type of signals use, depending on the media type: in copper cable uses electrical pulses, fiber uses lights and wireless uses radio transmissions.

External Signaling Interference

Noise from the electrical motors, fluorescent lights radio waves and other devices that are sources of noise can actually distort and drop or can corrupt the data that is being carried by the copper media, that is why the UTP is designed for. The Untwisted Shielded Pair, its outer jacket is designed to protect the wire inside against noises and of course physical damage. The twist of the pair wire is to protect the signal from interference, when the two wire are place together in the same position or in a straight form the noise coming from outside will create the same and continuous interference they received equal impact of the noise and that is why the signal will drop and stop sending a data into the destination.

                While if the two wires are twisted together the noise that hits the wire is not stable that would cause the unwanted noise or unwanted signal to lose because not all the part of the wire that the noise penetrate since the wire is twisted and not in a straight direction and the data will be sent successfully to its destination.

                Color coding of the wire inside electrically isolates wires from each other and identifies each pair, the color of the wire is designed to identify what pair is to twist for. (e.g.) The color orange is twisted to white orange and the green is twisted to white green and soon.

CHAPTER 8

CHAPTER 8

The upper OSI layer protocols such as the Data Link Layer, Network, Transport, Session, Presentation, and Application Layer they prepare data from the human network for transmission to its destination while the physical layer controls how data is placed on the communication media.

The role of OSI physical layer is to encode binary digits that present to Data Link layer frames into signals and to transmit and receive these signals across the physical media such as wireless, copper wire and optical fiber that connect network device.

There are three basic type of network media used for transmitting data such as copper cable, fiber and wireless. Each type of network media have different type of signals use, depending on the media type: in copper cable uses electrical pulses, fiber uses lights and wireless uses radio transmissions.

External Signaling Interference

Noise from the electrical motors, fluorescent lights radio waves and other devices that are sources of noise can actually distort and drop or can corrupt the data that is being carried by the copper media, that is why the UTP is designed for. The Untwisted Shielded Pair, its outer jacket is designed to protect the wire inside against noises and of course physical damage. The twist of the pair wire is to protect the signal from interference, when the two wire are place together in the same position or in a straight form the noise coming from outside will create the same and continuous interference they received equal impact of the noise and that is why the signal will drop and stop sending a data into the destination.

                While if the two wires are twisted together the noise that hits the wire is not stable that would cause the unwanted noise or unwanted signal to lose because not all the part of the wire that the noise penetrate since the wire is twisted and not in a straight direction and the data will be sent successfully to its destination.

                Color coding of the wire inside electrically isolates wires from each other and identifies each pair, the color of the wire is designed to identify what pair is to twist for. (e.g.) The color orange is twisted to white orange and the green is twisted to white green and soon.