Introduction to Ethernet and how does it work.pptx

will get to know more about Ethernet and how does it work and implementing

1. ETHERNET Unit:2 LAN Technologies

2. Introduction A system for connecting a number of computer systems to form a local area network, with protocols to control the passing of information and to avoid simultaneous transmission by two or more systems. ETHERNET 2 Ethernet Share All i mages

3. The most popular set of protocols for the physical and data link layers is Ethernet. Ethernet operates at the first two layer of the OSI model: Physical and Data link layers. Initially, Ethernet was given a name Alto Aloha Network . Ethernet was created by Robert Metcalfe in 1973. Metcalfe thought the name ether suitable because the cable used to build a network is a passive medium that permits the propagation of data. The cost of an Ethernet port on a node is very low compared to other technologies. Many vendors built Ethernet into motherboard of the computer so that it is not necessary to purchase a separate NIC. In Ethernet ,both layers are involved in the creation and transmission of frames . The physical layer is related to the type of LAN cabling and how the bits are transmitted and received on the cable. Ethernet divides the Data Link layer into two separate layers : Logical Link Control(LLC)layer and Medium Access Control(MAC)layer. The MAC sublayer address is the physical hardware address of the source and destination computer. All devices on a LAN must be identified by a unique MAC address. This sublayer controls which computer devices send and receive the data and allows NICs to communicate with the physical layer. The next level of processing is the LLC sublayer. It is responsible for identifying and passing data to the network layer protocol. ETHERNET 3 Ethernet

4. How Ethernet Works? Ethernet uses a protocol called CSMA/CD (Carrier Sense Multiple Access with Collision Detection). When one computer wanted to transmit, it would first check to see if any other machines were using the line. If the line was free, the sending computer tags the data it needed to send with a MAC (Media Access Control) address and loads it onto the network. The MAC address identifies the intended recipient so that the machine possessing that unique MAC address would accept the data and all the other machines on the network would ignore it. If the transmission line was busy, the computer would wait. If two machines try to send at the same time, each would react to the collision by waiting a random number of milliseconds before attempting to resend. The process was simple , but it was also very limited. Multiple collisions could quickly reduce the performance of a large network. For example, it is easy to eavesdrop on the network’s traffic with a fake MAC address. The network wasn’t very robust. Damage to any cable in the network could cause the entire system down. ETHERNET 4

5. Ethernet Technology Choices ETHERNET 5 The following options for implementing Ethernet networks are available: Half-and full-duplex Ethernet 10-Mbps Ethernet 100-Mbps Ethernet 1000-Mbps(1-Gbps or Gigabit) Ethernet 10-Gbps Ethernet OSI Ethernet Data Link Layer Logical Link Control(LLC) Medium Access Control(MAC) Physical Layer Standard Ethernet Fast Ethernet Gigabit Ethernet 10Base5 10Base2 10BaseT 10BaseFX 10BaseT 10BaseFX 10BaseSX 10BaseBX 100BaseT 100BaseTX 100BaseFX 100BaseSX 100BaseBX

6. Half-duplex and Full-duplex Ethernet Shared Ethernet is half duplex , i . e. a station is either transmitting or receiving traffic, but not both at once. A point-to-point ethernet link which supports simultaneous transmitting and receiving is called full-duplex ethernet. ETHERNET 6

7. 10-Mbps Ethernet Although 100-Mbps ethernet is beginning to replace 10-mbps ethernet,10-mbps ethernet can still play role in your network design, particularly at the access layer. For some customers 10-mbps capacity is sufficient. For some customers who have low bandwidth needs and a small budget,10mbps ethernet is an appropriate solution if the network does not need to scale to 100mbps in the future. ETHERNET 7

8. 100-Mbps Ethernet 100-mbps ethernet (also called Fast Ethernet and 100base-T ethernet), was initially standardized in IEEE 802.3u specification and is now merged into 2002 edition of IEEE 802.3. It is very similar to 10mbps ethernet. With some exceptions,100mbps ethernet is simply standard ethernet, just 10 times faster. ETHERNET 8

9. Gigabit Ethernet And 10-Gbps Ethernet Gigabit ethernet was initially defined in IEEE 802.3z specification and is now merged into the 2002edition of IEEE 802.3. it operates essentially like 100mbps ethernet, except that is 10 times faster. It uses a standard 802.3 frame format and frame size. 10-gbps ethernet: One of the reasons that Ethernet is such good choice for campus network designs is that it continues to grow with increasing bandwidth demands. The frame format of 10-gbps ethernet is same. This means that applications that use ethernet do not need to change. ETHERNET 9

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