Network Transmission Equipment
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Transcript of Network Transmission Equipment
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Network Transmission Equipment
Chapter 4
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Learning ObjectivesDescribe the purpose of LAN network transmission equipment:
NICs, repeaters, MAUs, hubs, bridges, routers, brouters, switches, and gateways
Explain how LAN network equipment works
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Learning ObjectivesDescribe the purpose of WAN network equipment:
Multiplexers, channel banks, private telephone networks, types of modems, ISDN adapters, access servers, and routers
Explain how WAN network equipment works
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LAN Transmission EquipmentNICs
Repeaters
MAUs
Hubs
Bridges
Routers
Brouters
Switches
Gateways
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NICEnables network device to connect to networkNetwork connection requirements
Appropriate connector for network mediumTransceiverController to support MAC sublayer of Data Link layerProtocol control firmware
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A Combination NIC
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Role of MAC Controller UnitWorks with firmware to correctly encapsulate:
Source and destination address information
Data to be transported
CRC error control information
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Transport andTransmission Options
Transport optionsCombined transport options make it easy to upgrade a network for high-speed communication
Transmissions optionsHalf-duplex transmissions
Full-duplex transmissions
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FDDI NICsConnect host systems/file servers to FDDI network equipment using single attachment
Attach network equipment to FDDI cabling via dual attachment
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ATM NICsConnect ATM switches or servers to an ATM network
Available to desktop
Relatively expensive
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Wireless NICModes
Ad hoc peer-to-peer communication with another wireless NIC
Communication with an access point
Provide flexibility and convenience
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Buses and NICsIndustry Standard Architecture (ISA)
Extended Industry Standard Architecture (EISA)
Microchannel Architecture (MCA)
Peripheral Computer Interface (PCI)
SPARC Bus (SBUS)
NuBus
Universal Serial Bus (USB)
VESA local bus (VL-bus)
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Choosing a NICFor host computer, server, or workstation?Network media and network transport methods in use?Manufacturer?Computer or network equipment bus type?Operating system used by the computer?Use of half- or full-duplex communications?How does it attach to network (for special application)?
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RepeaterAmplifies and retimes a packet or cell-carrying signal so that it can be sent along all outgoing cable segments attached to that repeater
Filters out signal disturbance or noise
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Repeaters Are Used to…Extend cable segment
Increase number of nodes beyond limit of one segment
Sense network problem and shut down cable segment (partitioning)
Connect to components in other network devices
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Repeaters Are Used to…Connect segments that use different media
Extend backbone cable segments in LANs and WANs
Extend long, fiber-optic cable segments
Increase communications distance of T-carrier lines
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A Multiport Repeater
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RepeatersAdvantage
Inexpensive way to extend a network
DisadvantageCan create excessive amount of network traffic
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Multistation Access Unit (MAU)
Central hub that links token ring nodes into a topology that physically resembles a star but in which data signals are transferred in a logical ring pattern
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MAUs Are Used to…Connect workstations into a logical ring through physical star topologyMove token and frames around the ringAmplify data signalsConnect in a daisy-chained manner to expand token ring networkProvide for orderly movement of dataShut down ports to malfunctioning nodes
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MAUsPassive hub
Active hub
Patch cables and lobe cables
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Ring In and Ring Out Ports
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Token Ring MAU Specifications
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HubCentral network device used in star topology to join networks
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Hubs Are Used to…Provide a central unit from which to connect multiple nodes into one networkPermit many computers to be connected on single or multiple LANsProvide multiprotocol servicesConsolidate network backboneProvide connections for different media typesEnable centralized network management and design
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Types of Network HubsUnmanaged hubs
Dual-speed hubs
Workgroup hubs
Stackable hubs
Chassis hubs
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BridgeConnects different LANs or LAN segments using the same access methodOperates in promiscuous mode; can look at frame addresses (unlike repeaters)Operates at MAC sublayer of OSI Data Link layerProtocol independent; only look at MAC address
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Bridges Are Used to…Extend a LAN when maximum connection limit has been reached
Extend a LAN beyond the length limit
Segment LANs to reduce data traffic bottlenecks
Prevent unauthorized access to a LAN
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Bridged Network
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Bridge FunctionsLearning
Filtering
Forwarding
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Cascade Bridging
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Advantages of BridgesLimit traffic to certain network segments; enhance performance
Can use as a firewall to keep intruders out of a network
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Types of BridgesLocal bridge
Connects networks in close proximity
Can be used to segment a portion of a network to reduce heavy traffic problems
Remote bridgeJoins networks across the same city, between cities, and between states to create one network
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BridgeToken ring source-route bridge
Incorporated into 802.5 token ring LAN specificationPerforms routing at OSI Network layer
Spanning tree algorithmEnsures that frames are not transmitted in an endless loopEnables frames to be sent along most cost-effective network path
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Bridge Protocol Data Units (BPDUs) Frame Format
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RouterConnects networks having the same or different access methods and media
Forwards packets to networks by using decision-making process based on:
Routing table data
Discovery of most efficient routes
Preprogrammed information from network administrator
Connects LAN at Network layer of OSI model
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Routers Are Used to…Efficiently direct packets from one network to another, reducing excessive traffic
Join neighboring or distant networks
Connect dissimilar networks
Prevent network bottlenecks by isolating portions of a network
Secure portions of a network from intruders
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Static and Dynamic RoutingStatic routing
Controls routing decisions by network administrator through preset routing instructions
Dynamic routingConstantly checks network configuration
Automatically updates routing tables
Makes decisions about how to route packets
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Routing Tables and ProtocolsRouting tables
Contain addresses of other routers
Routing protocolsRouting Information Protocol (RIP)
Communicates entire contents of routing tables to other routers
Open Shortest Path First (OSPF) protocolCommunicates information about immediate links to other nodes
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Advantages of OSPF ProtocolSends only the portion of routing table that pertains to its most immediate router links
Packages routing information in more compact format that RIP
Only updated routing table information is shared among routers, rather than the entire routing table
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BrouterActs as a bridge or a router, depending on how it is set up to forward a given protocol
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Brouters Are Used to…Handle packets efficiently on a multiprotocol network that includes some protocols that can be routed and some that cannot
Isolate and direct network traffic to reduce congestion
Join networks
Secure a certain portion of a network by controlling who can access it
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SwitchLinks network segments
Forwards and filters frames between segments
Provides bridging capacity and the ability to increase bandwidth on existing networks
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Switching TechniquesCut-through switching
Store-and-forward switching (buffered switching)
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GatewayEnables communications between two different types of networked systems
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Gateways Are Used to…Convert commonly used protocols to a specialized protocolConvert message formatsTranslate different addressing schemesLink a host computer to a LANProvide terminal emulationDirect electronic mail to the right network destinationConnect networks with different architectures
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Gateway
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WAN Transmission Equipment
Designed to work over POTS and leased telephone lines (T-carrier and ISDN)
May be analog or digital
Either converts a signal for long-distance communications or creates multiple channels
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Examples of Basic WAN Transmission Equipment
Multiplexers
Channel banks
Private telephone networks
Telephone modems
ISDN adapters
Cable TV modems
DSL modems and routers
Access servers
Routers
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Multiplexer (MUX)Can receive multiple inputs and transmit them to a shared network mediumWorks at OSI Physical layer, switching from channel to channel using:
A single method for optical transmissions (wavelength division multiplexing or WDM), orOne of three electrical switching methods
Time division multiple access (TDMA)Frequency division multiple access (FDMA)Statistical multiple access
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Using Multiplexers
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Channel BankLarge-scale multiplexer that combines telecommunications channels in a centralized location
First used in voice applications, now handle voice, data, and video
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Private Telephone NetworksPrivate branch exchanges (PBXs)
Private automatic exchanges (PAXs)
Private automatic branch exchanges (PABXs)
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Telephone ModemsConvert computer’s outgoing digital signal to analog signal that can be transmitted over a telephone line
Also convert incoming analog signal to a digital signal the computer can understand
Attached internally or externally
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Telephone ModemsTypes of connectors (DB-25, DB-9, PS/2, universal serial bus or USB)
Modem data transfer rate measured by baud rate or bits per second (bps)
Synchronous or asynchronous communication format
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ISDN AdaptersConnect a computer or fax to an ISDN line
Terminal adapter (TA) converts digital signal to a protocol that can be sent over a digital telephone line
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Cable TV ModemsDigital modem devices designed for use with cable TV system, providing high-speed data transfer
Share bandwidth with others, but dynamically allocate unused cable bandwidth
Either internal or external
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DSL Modems and RoutersDigital Subscriber Line (DSL)
Uses advanced modulation technologies on existing telecommunications networks for high-speed networking between subscriber and telco
Communication speeds up to 60 Mbps
Dedicated to single user; employs full bandwidth of the line
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Connecting to DSL
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Access ServersConnect synchronous and asynchronous devices to a network, providing routing for both types of communications
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Using an Access Server
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Remote RoutersJoin networks in WANs over long distances
Connect ATM, ISDN, frame relay, high-speed serial, and X.25 networks
Can support multiple protocols
Can be set up as firewalls
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Chapter SummaryNetwork transmission equipment used on LANs, WANs, or both
Modems
Bridges
Gateways
Channel banks
Access servers