Chapter 6 Chapter 6 Network TheoryNetwork Theory

prepared byprepared by

Mark BeierMark Beier

Edited By Richard Goldman

NICNIC

• NNetwork etwork IInterface nterface CCardard• The device that enables a The device that enables a

workstation, server, printer, or other workstation, server, printer, or other node to connect to the network.node to connect to the network.

• Network adapters belong to the Network adapters belong to the physical layer of the OSI Modelphysical layer of the OSI Model

• They come in many varietiesThey come in many varieties

BusBus

• The type of circuit used by the The type of circuit used by the system board to transmit data to system board to transmit data to componentscomponents

ISAISA

• IIndustry ndustry SStandard tandard AArchitecture rchitecture • The original PC bus, developed in The original PC bus, developed in

the early 1980’s to support an 8-bit the early 1980’s to support an 8-bit and later 16-bit data transfer and later 16-bit data transfer capability. Although an older capability. Although an older technology ISA buses are still used technology ISA buses are still used to connect serial devices, such as to connect serial devices, such as mice or modems in new PCsmice or modems in new PCs

MCAMCA

• MMicro icro CChannel hannel AArchitecturerchitecture• IBM’s proprietary 32-bit bus for IBM’s proprietary 32-bit bus for

personal computerspersonal computers• Introduced in 1987Introduced in 1987• Later replaced by the more Later replaced by the more

standard EISA and PCI busesstandard EISA and PCI buses

EISAEISA

• EExtended xtended IIndustry ndustry SStandard tandard AArchitecturerchitecture

• A 32-bit bus that is compatible with A 32-bit bus that is compatible with older ISA devices because it shares older ISA devices because it shares the same length and pin the same length and pin configuration as the ISA bus, but configuration as the ISA bus, but that uses a deeper slot connector that uses a deeper slot connector to achieve faster throughput. to achieve faster throughput.

PCIPCI

• PPeripheral eripheral CComponent omponent IInterconnectnterconnect• A 32- or 64-bit bus introduced in the A 32- or 64-bit bus introduced in the

1990s 1990s • The PCI bus is the NIC connection type The PCI bus is the NIC connection type

used for nearly all new PCs. used for nearly all new PCs. • Characterized by a shorter length than Characterized by a shorter length than

ISA, MCA, or EISA cardsISA, MCA, or EISA cards• A much faster data transmission A much faster data transmission

capability.capability.

PCMCIA--PC CardPCMCIA--PC Card

• PPersonal ersonal CComputer omputer MMemory emory CCard ard IInternational nternational AAssociationssociation

• An interface developed in the early 1990sAn interface developed in the early 1990s• Provides a standard interface for Provides a standard interface for

connecting any type of device to a connecting any type of device to a portable computerportable computer

• PCMCIA slots may hold modem cards, PCMCIA slots may hold modem cards, network interface cards, external hard network interface cards, external hard disk cards, or CD-ROM cards.disk cards, or CD-ROM cards.

• PCMCIA are also called PC CardsPCMCIA are also called PC Cards

FirmwareFirmware

• A combination of hardware and A combination of hardware and softwaresoftware

• The hardware component is a read-The hardware component is a read-only memory (ROM) chip that only memory (ROM) chip that stores data established at the stores data established at the factory and possibly changed by factory and possibly changed by configuration programs that can configuration programs that can write to ROM (EPROM).write to ROM (EPROM).

EPROMEPROM

• Stands for Stands for EErasable rasable PProgrammable rogrammable RRead ead OOnly nly MMemoryemory

• Firmware that may be erased with Firmware that may be erased with ultraviolet light and then ultraviolet light and then reprogrammedreprogrammed

EEPROMEEPROM

• EElectrically lectrically EErased rased PProgrammable rogrammable RRead ead OOnly nly MMemoryemory

• Flash ROMFlash ROM• Firmware that may be erased and Firmware that may be erased and

rewritten without removing it from rewritten without removing it from the circuit boardthe circuit board

IRQIRQ

• IInterrupt nterrupt RRequest Lineequest Line• The means by which a device can The means by which a device can

request attention from the CPUrequest attention from the CPU• IRQs are identified by numbers IRQs are identified by numbers

from 0 to 15from 0 to 15

CMOSCMOS

• CComplementary omplementary MMetal etal OOxide xide SSemiconductoremiconductor

• Firmware attached to the system Firmware attached to the system board or adapter cards that board or adapter cards that controls the configuration of a controls the configuration of a computer’s devicescomputer’s devices

BIOSBIOS

• BBasic asic IInput/nput/OOutput utput SSystemystem• Firmware that controls computer Firmware that controls computer

communication with its devicescommunication with its devices

Memory RangeMemory Range

• A hexadecimal number that A hexadecimal number that indicates the area of memory that indicates the area of memory that the NIC and CPU will use for the NIC and CPU will use for exchanging or buffering data. exchanging or buffering data.

• Some memory ranges are reserved Some memory ranges are reserved for specific devicesfor specific devices

Base I/O PortBase I/O Port

• A hexidecimal setting that A hexidecimal setting that designates which area of memory designates which area of memory will act as a channel for moving will act as a channel for moving data between the NIC and CPUdata between the NIC and CPU

• Like its IRQ, a device’s base I/O Like its IRQ, a device’s base I/O port cannot be used by any other port cannot be used by any other devicedevice

Loopback PlugLoopback Plug

• A connector used for troubleshooting A connector used for troubleshooting that plugs into a port that plugs into a port

• The connector plugs into a port, The connector plugs into a port, such as serial or parallel, and such as serial or parallel, and crosses of the transmit line to the crosses of the transmit line to the receive line so that outgoing signals receive line so that outgoing signals can be redirected back into the can be redirected back into the computer for testingcomputer for testing

RepeaterRepeater

• A connectivity device that A connectivity device that regenerates and amplifies an regenerates and amplifies an analog or digital signal.analog or digital signal.

HubHub

• A multiport repeater containing one A multiport repeater containing one port that connects to a network’s port that connects to a network’s backbone and multiple ports that backbone and multiple ports that connect to a group of workstations. connect to a group of workstations.

• Hubs regenerate digital signals.Hubs regenerate digital signals.• Hubs typically support a star or Hubs typically support a star or

hybrid topologyhybrid topology• They can be passive or intelligentThey can be passive or intelligent

Passive HubPassive Hub

• A hub that simply amplifies and A hub that simply amplifies and retransmits signals over the retransmits signals over the networknetwork

Intelligent HubIntelligent Hub

• A hub that possesses processing A hub that possesses processing capabilities and can therefore capabilities and can therefore monitor network traffic, detect monitor network traffic, detect packet errors and collisions, poll packet errors and collisions, poll connected devices for information, connected devices for information, and send the data gathered to a and send the data gathered to a management information base.management information base.

Standalone HubStandalone Hub

• A type of hub that serves a workgroup of A type of hub that serves a workgroup of computers that are separate from the computers that are separate from the rest of the network.rest of the network.

• A standalone hub may be connected to A standalone hub may be connected to another hub by a coaxial, fiber-optic, or another hub by a coaxial, fiber-optic, or twisted-pair cable.twisted-pair cable.

• Such hubs are not typically connected in Such hubs are not typically connected in a hierarchical or daisy-chain fashion.a hierarchical or daisy-chain fashion.

Stackable HubStackable Hub

• A type of hub designed to be linked A type of hub designed to be linked with other hubs in a single with other hubs in a single telecommunications closet. telecommunications closet.

• Stackable hubs linked together Stackable hubs linked together logically represent one large hub to logically represent one large hub to the network.the network.

Modular HubModular Hub

• A type of hub that provides a A type of hub that provides a number of interface options within number of interface options within one chassis. one chassis.

• Similar to a PC, a modular hub Similar to a PC, a modular hub contains a system board and slots contains a system board and slots accommodating different adapters. accommodating different adapters.

Managed HubManaged Hub

• A hub that possesses processing A hub that possesses processing capabilities and can therefore capabilities and can therefore monitor network traffic, detect monitor network traffic, detect packet errors and collisions, poll packet errors and collisions, poll connected devices for information, connected devices for information, and send the data gathered to a and send the data gathered to a management information base.management information base.

MIBMIB

• MManagement anagement IInformation nformation BBasease• A collection of data used by A collection of data used by

management programs to analyze management programs to analyze network performance and problemsnetwork performance and problems

BridgeBridge

• Looks like a repeaterLooks like a repeater• Has single input and single outputHas single input and single output• Unlike repeater, it can interpret Unlike repeater, it can interpret

data that it transmitsdata that it transmits• Bridging occurs at the Data-Link Bridging occurs at the Data-Link

layerlayer• A Bridge establishes a Filtering Data A Bridge establishes a Filtering Data

Base of known MAC addressesBase of known MAC addresses

Filtering DatabaseFiltering Database

• A collection of data created and A collection of data created and used by a bridge that correlates used by a bridge that correlates the MAC addresses of connected the MAC addresses of connected workstations with their locations.workstations with their locations.

• A filtering database is also known A filtering database is also known as a forwarding table.as a forwarding table.

Forwarding TableForwarding Table

• A collection of data created and A collection of data created and used by a bridge that correlates used by a bridge that correlates the MAC addresses of connected the MAC addresses of connected workstations with their locations.workstations with their locations.

• A forwarding table is also known as A forwarding table is also known as a filtering database.a filtering database.

Transparent BridgingTransparent Bridging

• The method of bridging used on The method of bridging used on most Ethernet networks.most Ethernet networks.

Source Route BridgingSource Route Bridging

• The method of bridging used on The method of bridging used on most Token Ring networks.most Token Ring networks.

Translational BridgingTranslational Bridging

• A method of bridging that can A method of bridging that can connect Token Ring and Ethernet connect Token Ring and Ethernet networks.networks.

SwitchSwitch

• A connectivity device that logically A connectivity device that logically subdivides a network into smaller, subdivides a network into smaller, individual collision domains.individual collision domains.

• A switch operates at the Data Link Layer A switch operates at the Data Link Layer of the OSI Model and can interpret MAC of the OSI Model and can interpret MAC address information to determine address information to determine whether to filter or forward packets it whether to filter or forward packets it receives.receives.

• Each port acts like a bridge.Each port acts like a bridge.

Collision DomainCollision Domain

• A portion of a LAN encompassing A portion of a LAN encompassing devices that may cause and detect devices that may cause and detect collisions among their group. collisions among their group.

• Bridges and switches can logically Bridges and switches can logically create multiple collision domainscreate multiple collision domains

Cut-through ModeCut-through Mode

• A switching mode in which a switch A switching mode in which a switch reads a frame’s header and reads a frame’s header and decides where to forward the data decides where to forward the data before it receives the entire packet. before it receives the entire packet.

• Cut-through Mode is faster, but less Cut-through Mode is faster, but less accurate, than the other switching accurate, than the other switching method, store and forward mode.method, store and forward mode.

RuntsRunts

• Packet fragmentsPacket fragments

Store and Forward ModeStore and Forward Mode

• A method of switching in which a switch A method of switching in which a switch reads the entire data frame into its reads the entire data frame into its memory and checks it for accuracy memory and checks it for accuracy before transmitting it.before transmitting it.

• While the method is more time While the method is more time consuming than the cut-through consuming than the cut-through method, it allows store and forward method, it allows store and forward switches to transmit data more switches to transmit data more accurately.accurately.

VLANVLAN

• VVirtual irtual LLocal ocal AArea rea NNetworketwork• The means by which a switch can The means by which a switch can

logically group a number of ports logically group a number of ports into a broadcast domain.into a broadcast domain.

• A VLAN can consist of servers, A VLAN can consist of servers, work-stations, printers, routers, or work-stations, printers, routers, or any other network device you can any other network device you can connect to a switch.connect to a switch.

Broadcast domainBroadcast domain

• In a Virtual Local Area Network In a Virtual Local Area Network (VLAN), a combination of ports that (VLAN), a combination of ports that make up a Layer 2 segment and make up a Layer 2 segment and must be connected by a Layer 3 must be connected by a Layer 3 devicedevice

Layer SwitchesLayer Switches

• Layer 3 SwitchLayer 3 Switch– A switch capable of interpreting data at A switch capable of interpreting data at

the Network Layer of the OSI Model.the Network Layer of the OSI Model.

• Layer 4 SwitchLayer 4 Switch– A switch capable of interpreting data at A switch capable of interpreting data at

the Transport Layer of the OSI Model.the Transport Layer of the OSI Model.

• **May also be called routing **May also be called routing switches or application switchesswitches or application switches

Routing SwitchRouting Switch

• Another term for a Layer 3 or Layer Another term for a Layer 3 or Layer 4 switch.4 switch.

• A routing switch comprises a hybrid A routing switch comprises a hybrid between a router and a switch and between a router and a switch and can therefore interpret data from can therefore interpret data from Layer 2 and either Layer 3 or Layer Layer 2 and either Layer 3 or Layer 4.4.

Application SwitchApplication Switch

• Another term for layer 3 or layer 4 Another term for layer 3 or layer 4 switchswitch

RouterRouter

• A multiport device that can connect A multiport device that can connect dissimilar LANs and WANs running a dissimilar LANs and WANs running a different transmission speeds and using a different transmission speeds and using a variety of protocols. variety of protocols.

• A router can determine the best path for A router can determine the best path for data transmission and perform advanced data transmission and perform advanced management functionsmanagement functions

• Routers operate at the Network layer or Routers operate at the Network layer or higher of the OSI Modelhigher of the OSI Model

• Routers are intelligent, protocol-dependent Routers are intelligent, protocol-dependent devices.devices.

Modular RouterModular Router

• A router with multiple slots that A router with multiple slots that can hold different interface cards can hold different interface cards or other devices so as to provide or other devices so as to provide flexible, customizable network flexible, customizable network interoperabilityinteroperability

Routing ProtocolsRouting Protocols

• The means by which routers The means by which routers communicate with each other abut communicate with each other abut network status. network status.

• Routing protocols determine the best Routing protocols determine the best path for data to take between modes.path for data to take between modes.

• Routing protocols are not identical to Routing protocols are not identical to routable protocols such as TCP/IP or routable protocols such as TCP/IP or IPX/SPX.IPX/SPX.

• They may piggyback on top of routable They may piggyback on top of routable protocolsprotocols

Convergence TimeConvergence Time

• The time it takes for a router to The time it takes for a router to recognize a best path in the event recognize a best path in the event of a change or outageof a change or outage

Bandwidth overheadBandwidth overhead

• The burden placed on the The burden placed on the underlying network to support a underlying network to support a routing protocolrouting protocol

RIPRIP

• RRouting outing IInformation nformation PProtocolrotocol• The oldest routing protocol that is still The oldest routing protocol that is still

widely used widely used • RIP does not work in very large network RIP does not work in very large network

environments where data may have to environments where data may have to travel through more than 16 routers to travel through more than 16 routers to reach its destinationreach its destination

• Compared to other routing protocols, RIP Compared to other routing protocols, RIP is slower and less secure.is slower and less secure.

OSPFOSPF

• OOpen pen SShortest hortest PPath ath FFirstirst• A routing protocol that makes up A routing protocol that makes up

for some of the limitations of RIP for some of the limitations of RIP and can coexist with RIP on a and can coexist with RIP on a networknetwork

EIGRPEIGRP

• EEnhanced nhanced IInterior nterior GGateway ateway RRouting outing PProtocolrotocol• A routing protocol developed in the mid-A routing protocol developed in the mid-

1980’s by Cisco Systems that1980’s by Cisco Systems that– has a fast convergence time, has a fast convergence time, – Has a low network overhead, Has a low network overhead, – is easier to configure is easier to configure – and less CPU-intensive than OSPF. and less CPU-intensive than OSPF. – Offers the benefits of supporting multiple Offers the benefits of supporting multiple

protocolsprotocols– Limits unnecessary network traffic between Limits unnecessary network traffic between

routersrouters

BGPBGP

• BBorder order GGateway ateway PProtocolrotocol• Routing protocol of Internet Routing protocol of Internet

backbonesbackbones• Most complex of routing protocolsMost complex of routing protocols• Designed with ability to use Designed with ability to use

100,000 different routes efficiently 100,000 different routes efficiently and fairlyand fairly

Bridge Router (Brouter)Bridge Router (Brouter)

• A router capable of providing layer A router capable of providing layer 2 bridging functions2 bridging functions

GatewayGateway

• A combination of networking hardware A combination of networking hardware and software that connects two and software that connects two dissimilar kinds of networks. dissimilar kinds of networks.

• Gateways perform Gateways perform – ConnectivityConnectivity– Session ManagementSession Management– Data TranslationData Translation

• Gateways must operate at multiple Gateways must operate at multiple layers of the OSI Model.layers of the OSI Model.

Broadband domainBroadband domain

• A combination of ports that make A combination of ports that make up a Layer 2 segment and must be up a Layer 2 segment and must be connected by a Layer 3 device in a connected by a Layer 3 device in a virtual local area networkvirtual local area network

This Show is overThis Show is over

• It’s Time for a breakIt’s Time for a break