The Ethernet Prepared by: Amer Al-Qadri Ahmad Abdul-Rahman Ismail khistah

Introduction What is Ethernet? What is Ethernet? History History General Description General Description 2

What is The Ethernet Ethernet refers to the family of local area networks (LAN) products covered by the IEEE that operates at many speeds. Ethernet refers to the family of local area networks (LAN) products covered by the IEEE that operates at many speeds. It defines a number of wiring for the physical layer, through means of Network access at the Media Access Control (MAC)/Data Link Layer, and a Common addressing format. It defines a number of wiring for the physical layer, through means of Network access at the Media Access Control (MAC)/Data Link Layer, and a Common addressing format. 3

What is The Ethernet (cont) The combination of the twisted pair versions of Ethernet with the fiber optic versions largely replacing standards such as coaxial cable Ethernet. The combination of the twisted pair versions of Ethernet with the fiber optic versions largely replacing standards such as coaxial cable Ethernet. In recent years, Wi-Fi, the wireless LAN standardized by IEEE , has been used instead of Ethernet for many home and small office networks and in addition to Ethernet in larger installations. In recent years, Wi-Fi, the wireless LAN standardized by IEEE , has been used instead of Ethernet for many home and small office networks and in addition to Ethernet in larger installations. 4

History The original Ethernet was developed as an experimental coaxial cable Network to operate with a data rate of 3 Mbps using (CSMA/CD) Protocol. The original Ethernet was developed as an experimental coaxial cable Network to operate with a data rate of 3 Mbps using (CSMA/CD) Protocol. Success with that project attracted early attention and specification and led to the 1980 joint development of the 10-Mbps Ethernet Version 1.0. Success with that project attracted early attention and specification and led to the 1980 joint development of the 10-Mbps Ethernet Version

History (cont) The draft standard was approved by the working group in 1983 and published as an official standard in The draft standard was approved by the working group in 1983 and published as an official standard in Since then, a number of supplements to the standard have been defined to take advantage of improvements in the technologies and to support: Since then, a number of supplements to the standard have been defined to take advantage of improvements in the technologies and to support: 1) additional network media 1) additional network media 2) higher data rate capabilities 2) higher data rate capabilities 6

General Description Ethernet was originally based on the idea of computers communicating over a shared coaxial cable acting as a broadcast transmission medium. Ethernet was originally based on the idea of computers communicating over a shared coaxial cable acting as a broadcast transmission medium. The common cable providing the communication channel was likened to the ether and it was from this reference that the name "Ethernet" was derived. The common cable providing the communication channel was likened to the ether and it was from this reference that the name "Ethernet" was derived. 7

General Description (cont) Three data rates are currently defined for operation over optical fiber and twisted- pair cables: Three data rates are currently defined for operation over optical fiber and twisted- pair cables: 10 Mbps—10Base-T Ethernet 10 Mbps—10Base-T Ethernet 100 Mbps—Fast Ethernet 100 Mbps—Fast Ethernet 1000 Mbps—Gigabit Ethernet 1000 Mbps—Gigabit Ethernet 8

Ethernet Network Elements Ethernet LANs consist of network nodes and interconnecting media. Ethernet LANs consist of network nodes and interconnecting media. The network nodes fall into two major classes: The network nodes fall into two major classes: 1) Data terminal equipment (DTE). 1) Data terminal equipment (DTE). 2) Data communication equipment (DCE). 2) Data communication equipment (DCE). The current Ethernet media options include two types of copper cable: (UTP) and (STP), plus several types of optical fiber cable. The current Ethernet media options include two types of copper cable: (UTP) and (STP), plus several types of optical fiber cable. 9

Repeaters The problem of shortness of coaxial cable. The problem of shortness of coaxial cable. The Repeater solves this problem. How? The Repeater solves this problem. How? Repeaters connect multiple Ethernet segments, listening to each segment and repeating the signal heard on one segment onto every other segment connected to the repeater. By running multiple cables and joining them with repeaters, you can significantly increase your network diameter. Repeaters connect multiple Ethernet segments, listening to each segment and repeating the signal heard on one segment onto every other segment connected to the repeater. By running multiple cables and joining them with repeaters, you can significantly increase your network diameter.

Repeater (cont) If a collision was detected, the repeater transmitted a jam signal onto all ports to ensure collision detection. If a collision was detected, the repeater transmitted a jam signal onto all ports to ensure collision detection. Repeaters could detect an improperly terminated link from the continuous collisions and stop forwarding data from it. Repeaters could detect an improperly terminated link from the continuous collisions and stop forwarding data from it.

Repeater (cont) The solution of cable breakages: when an Ethernet coax segment broke, while all devices on that segment were unable to communicate, repeaters allowed the other segments to continue working, although depending on which segment was broken and the layout of the network the partitioning that resulted may have made other segments unable to reach important servers and thus effectively useless. The solution of cable breakages: when an Ethernet coax segment broke, while all devices on that segment were unable to communicate, repeaters allowed the other segments to continue working, although depending on which segment was broken and the layout of the network the partitioning that resulted may have made other segments unable to reach important servers and thus effectively useless.

Bridges It is used to solve the problem with segmentation. It is used to solve the problem with segmentation. Bridges connect two or more network segments, increasing the network diameter as a repeater does, but bridges also help regulate traffic. Bridges connect two or more network segments, increasing the network diameter as a repeater does, but bridges also help regulate traffic. The bridge does not originate any traffic of its own; like a repeater, it only echoes what it hears from other stations. The bridge does not originate any traffic of its own; like a repeater, it only echoes what it hears from other stations.

Bridges (cont) One goal of the bridge is to reduce unnecessary traffic on both segments. It does this by examining the destination address of the frame before deciding how to handle it. One goal of the bridge is to reduce unnecessary traffic on both segments. It does this by examining the destination address of the frame before deciding how to handle it. By forwarding packets, the bridge allows any of the four devices By forwarding packets, the bridge allows any of the four devices in the figure in the figure to communicate. to communicate.

Bridges (cont) Destination address of A or B, bridge does nothing (bridge filters or drops the frame). Destination address of A or B, bridge does nothing (bridge filters or drops the frame). If the destination address is that of station C or D, then the bridge will transmit, or forward the frame If the destination address is that of station C or D, then the bridge will transmit, or forward the frame on to segment 2. on to segment 2.

Switching networks replace the shared medium of legacy Ethernet with a dedicated segment for each station. networks replace the shared medium of legacy Ethernet with a dedicated segment for each station. These segments connect to a switch, which acts much like an Ethernet bridge, but can connect many of these single station segments. These segments connect to a switch, which acts much like an Ethernet bridge, but can connect many of these single station segments.

Switching (cont) Since the only devices on the segments are the switch and the end station, the switch picks up every transmission before it reaches another node. Since the only devices on the segments are the switch and the end station, the switch picks up every transmission before it reaches another node.

Switching (cont) The switch then forwards the frame over the appropriate segment, just like a bridge, but since any segment contains only a single node, the frame only reaches the intended recipient. This allows many conversations to occur simultaneously on a switched network. The switch then forwards the frame over the appropriate segment, just like a bridge, but since any segment contains only a single node, the frame only reaches the intended recipient. This allows many conversations to occur simultaneously on a switched network.

Ethernet Network Topologies and Structures LANs take on many topological configurations, but regardless of their size or complexity, all will be a combination of only three basic interconnection structures: LANs take on many topological configurations, but regardless of their size or complexity, all will be a combination of only three basic interconnection structures: 1) The point-to-point interconnection. 1) The point-to-point interconnection. 2) A coaxial bus topology 2) A coaxial bus topology 3) The star-connected topology 3) The star-connected topology 19

The point-to-point interconnection The simplest structure and is known as a network link The simplest structure and is known as a network link Only two network units are involved Only two network units are involved the connection may be DTE-to-DTE, DTE-to- DCE, or DCE-to-DCE the connection may be DTE-to-DTE, DTE-to- DCE, or DCE-to-DCE The maximum allowable length of the link depends on: The maximum allowable length of the link depends on: 1) The type of cable 1) The type of cable 2) The transmission method that is used. 2) The transmission method that is used. 20

The point-to-point interconnection (cont) 21

A coaxial bus topology The original Ethernet networks were implemented with a coaxial bus structure The original Ethernet networks were implemented with a coaxial bus structure Segment lengths were limited to 500 meters and up to 100 stations. Segment lengths were limited to 500 meters and up to 100 stations. Individual segments could be interconnected with repeaters, as long as multiple paths did not exist between any two stations Individual segments could be interconnected with repeaters, as long as multiple paths did not exist between any two stations the number of DTEs did not exceed the number of DTEs did not exceed

A coaxial bus topology (cont) 23

The star-connected topology The central network unit is either a multiport repeater (also known as a hub) or a network switch The central network unit is either a multiport repeater (also known as a hub) or a network switch All connections are point-to-point links implemented with either twisted-pair or optical fiber cable. All connections are point-to-point links implemented with either twisted-pair or optical fiber cable. 24

The star-connected topology (cont) 25

The IEEE Logical Relationship to the ISO Reference Model The IEEE physical layer corresponds to the ISO physical layer. The IEEE physical layer corresponds to the ISO physical layer. the ISO data link layer is divided into two IEEE 802 sub-layers: the ISO data link layer is divided into two IEEE 802 sub-layers: 1) The Media Access Control (MAC) sub-layer. 1) The Media Access Control (MAC) sub-layer. 2) The MAC-client sub-layer. 2) The MAC-client sub-layer. 26

The IEEE Logical Relationship to the ISO Reference Model (cont) 27

The IEEE Logical Relationship to the ISO Reference Model (cont) The MAC-client sublayer may be one of the following: The MAC-client sublayer may be one of the following: 1) Logical Link Control (LLC), if the unit is a DTE. 1) Logical Link Control (LLC), if the unit is a DTE. - provides the interface between the Ethernet MAC and the upper layers. - provides the interface between the Ethernet MAC and the upper layers. 2) Bridge entity, if the unit is a DCE 2) Bridge entity, if the unit is a DCE - provide LAN-to-LAN interfaces between LANs - provide LAN-to-LAN interfaces between LANs 28

The IEEE Logical Relationship to the ISO Reference Model (cont) The MAC layer controls the node’s access to the network media and is specific to the individual protocol The MAC layer controls the node’s access to the network media and is specific to the individual protocol The physical layer is specific to the transmission data rate, the signal encoding, and the type of media interconnecting the two nodes The physical layer is specific to the transmission data rate, the signal encoding, and the type of media interconnecting the two nodes 29