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
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
Hybrid Physical TopologiesHybrid Physical Topologies
Daisy-ChainedDaisy-ChainedA A Daisy chainDaisy chain is linked series of devices is linked series of devices
A daisy-chained star-wired bus topology
Hybrid Physical TopologiesHybrid Physical Topologies
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
Wide Area Network (WAN) Wide Area Network (WAN) TopologiesTopologies
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
Wide Area Network (WAN) Wide Area Network (WAN) TopologiesTopologies
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
Wide Area Network (WAN) Wide Area Network (WAN) TopologiesTopologies
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
Wide Area Network (WAN) Wide Area Network (WAN) TopologiesTopologies
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