The EthernetThe Ethernet

Prepared by:Prepared by:

Amer Al-Qadri 237639Amer Al-Qadri 237639

Ahmad Abdul-Rahman 237837Ahmad Abdul-Rahman 237837

Ismail khistah 237697Ismail khistah 23769711

IntroductionIntroduction

• What is Ethernet?What is Ethernet?

• HistoryHistory

• General DescriptionGeneral Description

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What is The EthernetWhat is The Ethernet

• Ethernet refers to the family of local Ethernet refers to the family of local area networks (LAN) products covered area networks (LAN) products covered by the IEEE 802.3 that operates at many by the IEEE 802.3 that operates at many speeds.speeds.

• It defines a number of wiring for the It defines a number of wiring for the physical layer, through means of physical layer, through means of Network access at the Media Access Network access at the Media Access Control (MAC)/Data Link Layer, and a Control (MAC)/Data Link Layer, and a Common addressing format.Common addressing format.

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What is The Ethernet (cont)What is The Ethernet (cont)

• The combination of the twisted pair The combination of the twisted pair versions of Ethernet with the fiber optic versions of Ethernet with the fiber optic versions largely replacing standards such versions largely replacing standards such as coaxial cable Ethernet. as coaxial cable Ethernet.

• In recent years, Wi-Fi, the wireless LAN In recent years, Wi-Fi, the wireless LAN standardized by IEEE 802.11, has been standardized by IEEE 802.11, has been used instead of Ethernet for many home used instead of Ethernet for many home and small office networks and in addition and small office networks and in addition to Ethernet in larger installations.to Ethernet in larger installations.

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HistoryHistory

• The original Ethernet was developed The original Ethernet was developed as an experimental coaxial cable as an experimental coaxial cable Network to operate with a data rate Network to operate with a data rate of 3 Mbps using (CSMA/CD) Protocol.of 3 Mbps using (CSMA/CD) Protocol.

• Success with that project attracted Success with that project attracted early attention and specification and early attention and specification and led to the 1980 joint development of led to the 1980 joint development of the 10-Mbps Ethernet Version 1.0. the 10-Mbps Ethernet Version 1.0.

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History (cont)History (cont)

• The draft standard was approved by the The draft standard was approved by the 802.3 working group in 1983 and 802.3 working group in 1983 and published as an official standard in 1985. published as an official standard in 1985.

• Since then, a number of supplements to Since then, a number of supplements to the standard have been defined to take the standard have been defined to take advantage of improvements in the advantage of improvements in the technologies and to support:technologies and to support:

1)1) additional network mediaadditional network media 2)2) higher data rate capabilities higher data rate capabilities

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GeneralGeneral DescriptionDescription

• Ethernet was originally based on the Ethernet was originally based on the idea of computers communicating over idea of computers communicating over a shared coaxial cable acting as a a shared coaxial cable acting as a broadcast transmission medium.broadcast transmission medium.

• The common cable providing the The common cable providing the communication channel was likened to communication channel was likened to the ether and it was from this reference the ether and it was from this reference that the name "Ethernet" was derived.that the name "Ethernet" was derived.

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General Description (cont)General Description (cont)

• Three data rates are currently Three data rates are currently defined for operation over optical defined for operation over optical fiber and twisted-pair cables:fiber and twisted-pair cables:

• 10 Mbps—10Base-T Ethernet10 Mbps—10Base-T Ethernet

• 100 Mbps—Fast Ethernet100 Mbps—Fast Ethernet

• 1000 Mbps—Gigabit Ethernet1000 Mbps—Gigabit Ethernet

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Ethernet Network Ethernet Network ElementsElements• Ethernet LANs consist of network nodes and Ethernet LANs consist of network nodes and

interconnecting media.interconnecting media.

• The network nodes fall into two major The network nodes fall into two major classes:classes:

1) 1) Data terminal equipment (DTE).Data terminal equipment (DTE).

2) 2) Data communication equipment (DCE).Data communication equipment (DCE).

• The current Ethernet media options include The current Ethernet media options include two types of copper cable: (UTP) and (STP), two types of copper cable: (UTP) and (STP), plus several types of optical fiber cable.plus several types of optical fiber cable.

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RepeatersRepeaters

• 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 Repeaters connect multiple Ethernet segments, listening to each segment and segments, listening to each segment and repeating the signal heard on one segment repeating the signal heard on one segment onto every other segment connected to the onto every other segment connected to the repeater. By running multiple cables and repeater. By running multiple cables and joining them with repeaters, you can joining them with repeaters, you can significantly increase your network diameter. significantly increase your network diameter.

Repeater (cont)Repeater (cont)

• If a collision was detected, the If a collision was detected, the repeater transmitted a jam signal repeater transmitted a jam signal onto all ports to ensure collision onto all ports to ensure collision detection. detection.

• Repeaters could detect an Repeaters could detect an improperly terminated link from the improperly terminated link from the continuous collisions and stop continuous collisions and stop forwarding data from it. forwarding data from it.

Repeater (cont)Repeater (cont)

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

BridgesBridges

• It is used to solve the problem with It is used to solve the problem with segmentation.segmentation.

• Bridges connect two or more network Bridges connect two or more network segments, increasing the network segments, increasing the network diameter as a repeater does, but bridges diameter as a repeater does, but bridges also help regulate traffic. also help regulate traffic.

• The bridge does not originate any traffic of The bridge does not originate any traffic of its own; like a repeater, it only echoes its own; like a repeater, it only echoes what it hears from other stations. what it hears from other stations.

Bridges (cont)Bridges (cont)

• One goal of the bridge is to reduce One goal of the bridge is to reduce unnecessary traffic on both segments. It unnecessary traffic on both segments. It does this by examining the destination does this by examining the destination address of the frame before deciding how address of the frame before deciding how to handle it. to handle it.

• By forwarding packets, the bridge allows By forwarding packets, the bridge allows any of the four devices any of the four devices

in the figurein the figure

to communicate. to communicate.

Bridges (cont)Bridges (cont)

• Destination address of A or B, bridge Destination address of A or B, bridge does nothing (bridge filters or drops does nothing (bridge filters or drops the frame). the frame).

• If the destination address is that of If the destination address is that of station C or D, then the bridge will station C or D, then the bridge will transmit, or forward the frametransmit, or forward the frame

on to segment 2. on to segment 2.

SwitchingSwitching

• networks replace the shared medium networks replace the shared medium of legacy Ethernet with a dedicated of legacy Ethernet with a dedicated segment for each station. segment for each station.

• These segments connect to a switch, These segments connect to a switch, which acts much like an Ethernet which acts much like an Ethernet bridge, but can connect many of bridge, but can connect many of these single station segments. these single station segments.

Switching (cont)Switching (cont)

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

Switching (cont)Switching (cont)

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

Ethernet Network Ethernet Network Topologies and StructuresTopologies and Structures

• LANs take on many topological LANs take on many topological configurations, but regardless of their configurations, but regardless of their size or complexity, all will be a size or complexity, all will be a combination of only three basic combination of only three basic interconnection structures:interconnection structures:

1) 1) The point-to-point interconnection.The point-to-point interconnection.

2) 2) A coaxial bus topologyA coaxial bus topology

3) 3) The star-connected topologyThe star-connected topology

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The point-to-point The point-to-point interconnectioninterconnection

• The simplest structure and is known as The simplest structure and is known as a network linka network link

• Only two network units are involvedOnly two network units are involved

• the connection may be DTE-to-DTE, the connection may be DTE-to-DTE, DTE-to-DCE, or DCE-to-DCEDTE-to-DCE, or DCE-to-DCE

• The maximum allowable length of the The maximum allowable length of the link depends on:link depends on:

1) 1) The type of cable The type of cable

2) 2) The transmission method that is used.The transmission method that is used.

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The point-to-point The point-to-point interconnectioninterconnection(cont)(cont)

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A coaxial bus topologyA coaxial bus topology

• The original Ethernet networks were The original Ethernet networks were implemented with a coaxial bus structureimplemented with a coaxial bus structure

• Segment lengths were limited to 500 Segment lengths were limited to 500 meters and up to 100 stations.meters and up to 100 stations.

• Individual segments could be Individual segments could be interconnected with repeaters, as long as interconnected with repeaters, as long as multiple paths did not exist between any multiple paths did not exist between any two stations two stations

• the number of DTEs did not exceed 1024.the number of DTEs did not exceed 1024.

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A coaxial bus topology A coaxial bus topology (cont)(cont)

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The star-connected The star-connected topologytopology

• The central network unit is either a The central network unit is either a multiport repeater (also known as a multiport repeater (also known as a hub) or a network switchhub) or a network switch

• All connections are point-to-point All connections are point-to-point links implemented with either links implemented with either twisted-pair or optical fiber cable.twisted-pair or optical fiber cable.

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The star-connected topology The star-connected topology (cont)(cont)

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The IEEE 802.3 Logical The IEEE 802.3 Logical Relationship to the ISO Relationship to the ISO Reference ModelReference Model

• The IEEE 802.3 physical layer The IEEE 802.3 physical layer corresponds to the ISO physical corresponds to the ISO physical layer.layer.

• the ISO data link layer is divided into the ISO data link layer is divided into two IEEE 802 sub-layers:two IEEE 802 sub-layers:

1) 1) The Media Access Control (MAC) sub-layer.The Media Access Control (MAC) sub-layer.

2) 2) The MAC-client sub-layer.The MAC-client sub-layer.

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The IEEE 802.3 Logical The IEEE 802.3 Logical Relationship to the ISO Relationship to the ISO Reference Model (cont)Reference Model (cont)

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The IEEE 802.3 Logical The IEEE 802.3 Logical Relationship to the ISO Relationship to the ISO Reference Model (cont)Reference Model (cont)• The MAC-client sublayer may be one The MAC-client sublayer may be one

of the following:of the following: 1)1) Logical Link Control (LLC), if the unit is a Logical Link Control (LLC), if the unit is a

DTE.DTE.

- provides the interface between the Ethernet - provides the interface between the Ethernet MAC and the upper layers.MAC and the upper layers.

2) 2) Bridge entity, if the unit is a DCEBridge entity, if the unit is a DCE

- provide LAN-to-LAN interfaces between LANs - provide LAN-to-LAN interfaces between LANs

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The IEEE 802.3 Logical The IEEE 802.3 Logical Relationship to the ISO Relationship to the ISO Reference Model (cont)Reference Model (cont)• The MAC layer controls the node’s access The MAC layer controls the node’s access

to the network media and is specific to the to the network media and is specific to the individual protocolindividual protocol

• The physical layer is specific to the The physical layer is specific to the transmission data rate, the signal transmission data rate, the signal encoding, and the type of media encoding, and the type of media interconnecting the two nodesinterconnecting the two nodes

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