Chapter 5 - Physical Topology/Logical Topology

TOPOLOGYTOPOLOGY

Physical topologyPhysical topology

Physical layout of a networkPhysical layout of a network

SIMPLE PHYSICAL TOPOLOGIES

A A Bus topologyBus topology consists of a single cable— consists of a single cable—called a called a busbus— connecting all nodes on a — connecting all nodes on a network without intervening connectivity network without intervening connectivity devicesdevices

Bus topology network

A terminated bus network

Ring topologyRing topologyEach node is connected to the two nearest nodes so the Each node is connected to the two nearest nodes so the

entire network forms a circleentire network forms a circleOne method for passing data on ring networks is One method for passing data on ring networks is token token

passingpassing

A typical ring network

Star topologyStar topologyEvery node on the network is connected through a Every node on the network is connected through a

central devicecentral device

A typical star topology network

Hybrid Physical TopologiesHybrid Physical TopologiesHybrid topologyHybrid topology

Complex combination of the simple Complex combination of the simple physical topologiesphysical topologies

HierarchicalHierarchical hybrid topology hybrid topology

Star-wired ringStar-wired ring

Star-wired busStar-wired bus

Daisy-ChainedDaisy-Chained

Star-wired ringStar-wired ringStar-wired topologiesStar-wired topologies use physical layout of a use physical layout of a

star in conjunction with token ring-passing data star in conjunction with token ring-passing data transmission methodtransmission method

A star-wired ring topology network

Hybrid Physical TopologiesHybrid Physical Topologies


Star-wired busStar-wired busIn a In a star-wired bus topologystar-wired bus topology, groups of workstations are star-, groups of workstations are star-

connected to hubs and then networked via a single busconnected to hubs and then networked via a single bus

A star-wired bus network topology


Daisy-ChainedDaisy-ChainedA A Daisy chainDaisy chain is linked series of devices is linked series of devices

A daisy-chained star-wired bus topology


Hierarchical hybrid topologyHierarchical hybrid topologyUses layers to separate devices by priority or functionUses layers to separate devices by priority or function

A hierarchical ring topology

Enterprise-Wide TopologiesEnterprise-Wide Topologies

EnterpriseEnterprise An entire organizationAn entire organization

Backbone networksBackbone networks Serial backboneSerial backbone Distributed backboneDistributed backbone Collapsed backboneCollapsed backbone Parallel backboneParallel backbone

Enterprise-Wide TopologiesEnterprise-Wide TopologiesSerial backboneSerial backbone

Two or more hubs connected to each other by a single cableTwo or more hubs connected to each other by a single cable

Distributed backboneDistributed backboneHubs connected to a series of central hubs or routers in a hierarchyHubs connected to a series of central hubs or routers in a hierarchy

A simple distributed backbone network

Enterprise-Wide TopologiesEnterprise-Wide Topologies

A distributed backbone connecting multiple LANs

VA GA NC

Enterprise-Wide TopologiesEnterprise-Wide TopologiesCollapsed backboneCollapsed backbone

Uses a router or switch as the single central connection Uses a router or switch as the single central connection point for multiple subnetworkspoint for multiple subnetworks

A collapsed backbone network

Enterprise-Wide TopologiesEnterprise-Wide TopologiesParallel BackboneParallel Backbone

Collapsed backbone arrangement that consists of more than one Collapsed backbone arrangement that consists of more than one connection from central router or switch to each network segmentconnection from central router or switch to each network segment

A parallel backbone network

Enterprise-Wide TopologiesEnterprise-Wide TopologiesMesh networksMesh networks

Routers are interconnected with other routers, with at least two Routers are interconnected with other routers, with at least two pathways connecting each routerpathways connecting each router

An example of a mesh network

Wide Area Network (WAN) Wide Area Network (WAN) TopologiesTopologies

Peer-to-peer topologyPeer-to-peer topologyWAN with single interconnection points for each locationWAN with single interconnection points for each locationDedicated circuitsDedicated circuits

Continuous physical or logical connections between two Continuous physical or logical connections between two access points that are leased from a communication provideraccess points that are leased from a communication provider

A peer-to-peer WAN


Ring WAN topologyRing WAN topologyEach site is connected to two other sites so that entire WAN Each site is connected to two other sites so that entire WAN

forms a ring patternforms a ring pattern

A ring-configured WAN


Star WAN topologyStar WAN topologySingle site acts as the central connection point for several Single site acts as the central connection point for several

other pointsother points

A star-configured WAN


Mesh WAN topologyMesh WAN topologyMany directly interconnected locations forming a complex meshMany directly interconnected locations forming a complex mesh

Full-mesh and partial-mesh WANs


Tiered WAN topologyTiered WAN topologySites connected in star or ring formations are interconnected at Sites connected in star or ring formations are interconnected at

different levels, with interconnection points organized into layersdifferent levels, with interconnection points organized into layers

A tiered WAN topology

Logical TopologiesLogical Topologies

Refers to the way in which data are Refers to the way in which data are transmitted between nodestransmitted between nodes

Describes the way:Describes the way: Data are packaged in framesData are packaged in frames Electrical pulses are sent over network’s physical Electrical pulses are sent over network’s physical

mediamedia

Logical topology may also be called Logical topology may also be called network network transport systemtransport system

SwitchingSwitching

Component of network’s logical topology that Component of network’s logical topology that determines how connections are created determines how connections are created between nodesbetween nodes Circuit switchingCircuit switching

Connection is established between two network nodes Connection is established between two network nodes before they begin transmitting databefore they begin transmitting data

Message switchingMessage switchingEstablishes connection between two devices, transfers Establishes connection between two devices, transfers information to second device, and then breaks connectioninformation to second device, and then breaks connection

Packet switchingPacket switchingBreaks data into packets before they are transmittedBreaks data into packets before they are transmitted

EthernetEthernet

Carrier Sense Multiple Access with Collision Carrier Sense Multiple Access with Collision Detection (CSMA/CD)Detection (CSMA/CD) The The access methodaccess method used in Ethernet used in Ethernet CollisionCollision

In Ethernet networks, the interference of one network node’s In Ethernet networks, the interference of one network node’s data transmission with another network node’s data data transmission with another network node’s data transmissiontransmission

JammingJammingPart of CSMA/CD in which, upon detection of collision, Part of CSMA/CD in which, upon detection of collision, station issues special 32-bit sequence to indicate to all nodes station issues special 32-bit sequence to indicate to all nodes on Ethernet segment that its previously transmitted frame on Ethernet segment that its previously transmitted frame has suffered a collision and should be considered faultyhas suffered a collision and should be considered faulty

EthernetEthernet

CSMA/CD process

EthernetEthernet

Collision domainCollision domain Segment on a network in which collisions will Segment on a network in which collisions will

occur if two nodes transmit data at same timeoccur if two nodes transmit data at same time

Data propagation delayData propagation delay Length of time data take to travel from one point Length of time data take to travel from one point

on the segment to another pointon the segment to another point

EthernetEthernetDemand priorityDemand priority

Method for data transmission used by 100BaseVG Ethernet networksMethod for data transmission used by 100BaseVG Ethernet networks Demand priority requires an Demand priority requires an intelligent hubintelligent hub

CSMA/CD versus demand priority

EthernetEthernet

Traditional Ethernet LANs, called Traditional Ethernet LANs, called shared shared EthernetEthernet, supply fixed amount of bandwidth , supply fixed amount of bandwidth that must be shared by all devices on a segmentthat must be shared by all devices on a segmentSwitchSwitch Device that can separate network segments into Device that can separate network segments into

smaller segments, with each segment being smaller segments, with each segment being independent of the others and supporting its own independent of the others and supporting its own traffictraffic

Switched EthernetSwitched Ethernet Newer Ethernet model that enables multiple nodes to Newer Ethernet model that enables multiple nodes to

simultaneously transmit and receive data over logical simultaneously transmit and receive data over logical network segmentsnetwork segments

EthernetEthernet

Figure 5-21: A switched Ethernet network

EthernetEthernet

Gigabit EthernetGigabit Ethernet 1 Gigabit Ethernet1 Gigabit Ethernet

Ethernet standard for networks that achieve 1-Ethernet standard for networks that achieve 1-Gbps maximum throughputGbps maximum throughput

10 Gigabit Ethernet10 Gigabit EthernetStandard currently being defined by IEEE 802.3ae Standard currently being defined by IEEE 802.3ae committeecommittee

Will allow 10-Gbps throughputWill allow 10-Gbps throughput

Will include full-duplexing and multimode fiber Will include full-duplexing and multimode fiber requirementsrequirements

Understanding Frame TypesUnderstanding Frame Types

Learning about networks is analogous to Learning about networks is analogous to learning a foreign language, with the frame type learning a foreign language, with the frame type being the language’s syntaxbeing the language’s syntax Just as you may know the Japanese word for go but Just as you may know the Japanese word for go but

how to use it in a sentence, you may know all about how to use it in a sentence, you may know all about the IPX/SPX protocol but not how devices handle itthe IPX/SPX protocol but not how devices handle it

AutosenseAutosense Feature of modern NICs that enables a NIC to Feature of modern NICs that enables a NIC to

automatically sense what types of frames are running automatically sense what types of frames are running on a network and set itself to that specificationon a network and set itself to that specification

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Chapter 5 - Physical Topology/Logical Topology