Topics*Network TopologyCables and connectorsNetwork Devices

Network Topologies*LANs and WANs - Geographical coverageLANs A single geographical location, such as office building, school, etcTypically High speed and cheaper.WANsSpans more than one geographical location often connecting separated LANsSlowerCostly hardware, routers, dedicated leased lines and complicated implementation procedures.

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Network Topologies*Topology - Physical and logical network layoutPhysical actual layout of the computer cables and other network devicesLogical the way in which the network appears to the devices that use it.Common topologies:Bus, ring, star, mesh and wireless

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Bus topology*Uses a trunk or backbone to which all of the computers on the network connect.Systems connect to this backbone using T connectors or taps.Coaxial cablings ( 10Base-2, 10Base5) were popular options years ago.

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Bus Topology*

AdvantagesDisadvantagesCheap and easy to implementNetwork disruption when computers are added or removedRequire less cableA break in the cable will prevent all systems from accessing the network.Does not use any specialized network equipment.Difficult to troubleshoot.

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Ring Topology*Logical ringMeaning that data travels in circular fashion from one computer to another on the network.Typically FDDI, SONET or Token Ring technology are used to implement a ring networkRing networks are most commonly wired in a star configurationToken Ring has multi-station access unit (MSAU),equivalent to hub or switch. MSAU performs the token circulation internally.

*To create the complete ring, the Ring In (RI) port on each MASU is connected to the Ring Out (RO) port an another MSAU. The last MASU in the ring is then connected to the first, to complete the ring.

FDDI: Fiber Distributed Data Interface

Ring Topology*

AdvantagesDisadvantagesCable faults are easily located, making troubleshooting easierExpansion to the network can cause network disruptionRing networks are moderately easy to installA single break in the cable can disrupt the entire network.

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Star Topology*All computers/devices connect to a central device called hub or switch. Each device requires a single cable point-to-point connection between the device and hub.Most widely implementedHub is the single point of failure

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Star Topology*

AdvantagesDisadvantagesEasily expanded without disruption to the networkRequires more cableCable failure affects only a single userA central connecting device allows for a single point of failureEasy to troubleshoot and isolate problemsMore difficult to implement

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Mesh Topology*Each computer connects to every other. High level of redundancy.Rarely used.Wiring is very complicatedCabling cost is highTroubleshooting a failed cable is trickyA variation hybrid mesh create point to point connection between specific network devices, often seen in WAN implementation.

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Mesh Topology*

AdvantagesDisadvantagesProvides redundant paths between devicesRequires more cable than the other LAN topologiesThe network can be expanded without disruption to current usesComplicated implementation

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Wireless networking*Do not require physical cablingParticularly useful for remote access for laptop usersEliminate cable faults and cable breaks.Signal interference and security issue.

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Wireless networking*

AdvantagesDisadvantagesAllows for wireless remote accessPotential security issues associated with wireless transmissionsNetwork can be expanded without disruption to current usersLimited speed in comparison to other network topologies

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Cabling and ConnectorsGeneral media considerationsBroadband versus basebandBaseband transmissions use digital signaling and Time Division Multiplexing (TDM)Broadband transmissions use analog and Frequency Division Multiplexing(FDM)Dialog modes: Simplex, half duplex and full duplex

*EMI: is a problem when cables are installed near electrical devices, such as air conditions or fluorescent light fixtures. Crosstalk: refers to how the data signals on two separate media interfere with each other.

Cabling and Connectors*Media interferenceElectromagnetic interference (EMI) and cross talkNetwork media vary in their resistance to the effect of EMC. UTP is susceptible and fiber is resistantAttenuation Resistance :Coaxial cable > UTP, STP > UTP, Fiber > allMaximum distanceRepeatersAttenuation-related problems require a network analyzer to detectBandwidthTransmission capacity of a mediaData throughput is measured in bits per second(bps), Mbps, and GbpsFor todays application-intensive networks, Old 10Mbps is not enough, 100Mbps is very common and 1000Mbps is used too.

Network MediaCable-based mediaCoaxialCopper wire to conduct the signals electronicallyWas the choice for LAN for many years. RetiringTwisted pairCopper wire to conduct tooMost widely usedFiber-optictransmits the signals as lightUses glass or plastic conductor and High Cost. Restricted to where segment length and higher speeds are needed.Server room, backbone

*Carry signals between computers: Cable-based media and wireless networking.

Twisted-pair cablingHas been around for a long timeCreated for voice transmissions Most widely used media for networkingLighterMore flexibleEasier to installCheaperGreater speedsTwo types: Unshielded twisted pair (UTP)Shielded twisted pair (STP)

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Twisted-pair cablingUTP is more commonplaceSTP provides the extra shielding by using an insulating material wrapped around the wireGreater resistance to EMI and attenuationMore cost

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Five main categories

CategoryCable TypesApplication1UTPAnalog voice2UTPDigital voice, 1Mbps data3UTP, STP16Mbps data4UTP, STP20Mbps data5, 5eUTP, STPData, 100Mbps, 1G6, 6eUTP, STPData, 1G, 10G

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RJ-45 connectorsRJ-45 are used with twisted-pair cabling.Resemble ordinary phone jacks (RJ-11)Eight wires instead of fourLarger.Check out this page for how to make cat5 cable. http://www.tomax7.com/aplus/cat5.htm

*Cat6 http://www.youtube.com/watch?v=ht8Di4HdyZM

Fiber-optic cableUse light transmissionsEMI, crosstalk and attenuation become no issue.Well suited for data, video and voice transmissionsMost secure of all cable mediaInstallation and maintenance procedures require skillsCost of cableCost of retrofitting of existing network equipment because incompatible with most electronic network equipment

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Fiber-optic cableSingle mode fiber: A single direct bean of light, allowing for greater distances and increased transfer speeds.Multimode fiber: Many beams of light travel through the cable This strategy weakens the signal, reducing the length and speed the data signal can travel.

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Fiber-optic connectorsMIC, Standard FDDI connectorFCLCThere are a variety of connectors and several ways of Connecting these connectors, such bayonet, snap-lock, and push-pull connectors. A couple here:SC duplexSTSC

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Wireless mediaThree types:Radio waveInfraredMicrowaveSpeeds of wireless solutions dont keep pace with cable solutionsInstallation and maintenance are far more complicated and costly.Some solutions require line-of-sight, such as infrared and microwave.

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IEEE 802.3 standardsIEEE 802.3 standards defines a range of networking systems that are bases on the original Ethernet standard.

StandardCable typeSegment LengthConnectorTopology10Base2Thin Coaxial185 metersBNCPhysical bus10Base5Thick Coaxial500 metersVampire TapsPhysical bus10BaseTCategory 3,4,5 twisted pair100 metersRJ-45Physical star

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Fast Ethernet IEEE 802.3u

StandardCable TypeSegment LengthConnectorTopology100BaseTxCategory 5 UTP100 metersRJ-45Physical star100BaseT4Category 3,4,5 UTP100 metersRJ-45Physical star100BaseFXMultimode/Single-mode fiber-optic cable412/Multimode fiber-optic 10,000/single-mode fiber-opticSC,ST,MICPhysical star

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Gigabit Ethernet 802.3z and 802.3ab

StandardCable TypeSegment lengthConnector1000BaseLXMultimode/ single-mode fiber550/multimode5000/single-modeFiber connectors1000BaseSXMultimode fiber550 meters using 50 Micron multimode fiberFiber connectors1000BaseCXSTP twisted pair25 meters9-pin shielded connector, 8-pin fiber channel type 2 connector1000BaseT Category 5 UTP100 metersRJ-45

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*Check out this page for how to make cat5 cable. http://www.tomax7.com/aplus/cat5.htmColor codes

*In the world of structured cabling systems the cryptic number 568 refers to the order in which the individual wires inside a CAT 5 cable are terminated. The termination could come at either the users end socket, the patch panel or termination frame or even the individual leads that connect a computer to the wall socket. There are currently two different specifications with respect to the order these cables should be terminated contained in the international standards document (ISO/IEC 11801:1995) as previously mentioned there is no indication as to which of these standards is preferred.

*Pin Number Designations There are pin number designations for each color in T568B The pin designations are as follows: Color Codes for T568B Pincolor pair name --- ----- ---- --------- 1 wh/or 2 TxData + 2 or 2 TxData 3 wh/grn 3 RecvData+ 4 blu 1 5 wh/blu 1 6 grn 3 RecvData- 7 wh/brn 4 8 brn 4

*The pinouts for a crossover cable

Straight-through Crossover cable

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*Networking Devices

repeatersHubsSwitchesBridgesRoutesGatewaysNetwork Interface Cards (NICs)Wireless access pointsModemsPunch_down panels

*Slelecting devices:

Hubs*The bottom of the networking food chainConnect device and create larger networksSmall hubs 5-8 ports (workgroup hubs)Some hubs have more ports, up to 32 normallyDirect data packets to all devices connected to the hub - shared bandwidth

animationScalability, Collision, inefficient

*http://www2.rad.com/networks/1997/nettut/hub.html

Bridges*Divide larger networks into smaller sectionsCheck MAC address, forward or block the dataLearning bridge builds list of MAC address by watching the traffic on the network.Two issues to consider:Placement 80/20 ruleBridging loopsIEEE 802.1d Spanning tree protocol Types of bridgesTransparent bridgeSource route bridgeTranslational bridge

*Transparent bridge: forward or block based on MAC

Source route bridge: Used in Token ring network. The entire path is embedded within the packet.

Translational bridge: convert one networking data format to another.

Bridges*Source Route BridgeUsed in Token Ring networks.The entire path (ring number and bridge number) is embedded within PacketSearch frameRoute discovery frame

Translational bridgeUsed to convert one networking data format to another.For example, from Token Ring to Ethernet and vice versa.

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Switches*Like hub, connectivity points of Ethernet networkForward only to the port that connects to the destination deviceknows MAC addressMatch the MAC address in the data it receives.Fully switched network, a dedicated segment for each device is connected to switch. Expensive.

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Switches*Allow full duplex EthernetNodes only communicate with switch, never directly to each otherUse twisted pair or fiber optic cabling, using separate conductors for sending and receiving data.collision pair is used to transmit dataIt was half duplex before one device can transmit at one given time, double the capacity, 100Mbps become 200MbpsMost LAN are mixed with hubs and switches.

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*http://www.cisco.com/warp/public/473/lan-switch-cisco.shtml

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Switch routing method*Packet-based switches use one of the following method to route packet.Cut-through Forward as soon as it received the destination MAC first 14 bytesCan cause propagation of errorStore-and-forwardError checked before being forwardedErrors are not propagated through networkBad frames are discardedError checking takes time. Considerably slower

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Switch Routing Method*FragmentFree Take the advantage of both.Check errors by reading the first 64byte of packets where collision most likely happensOffer near cut-through switching performance

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Switch physical design*LAN switches vary in their physical designShared-memoryCommon buffer for all portsMatrixInternal grid with input port and output crossing each other First check MAC, then switch makes a connection where two ports (input/output) intersectBus-architectureCommon-busDedicated buffer for each port and a circuit to control the bus access

*CASE: buffer overflowOur switch has a 2G buffer, it connected to all servers, including backup servers. Every night, about 2TB data being backed up. Network was too busy.

Switch and Transparent Bridging*Most LAN switches use transparent bridging to create address lookup tablesTransparent bridging is a technology that allows a switch to learn everything it needs to know about the location of nodes on the network within the network administrator having to do anything. Has five parts:LearningFloodingFilteringForwardingAging

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*http://computer.howstuffworks.com/lab-switch10.htmhttp://www.cisco.com/warp/public/473/lan-switch-transparent.swf

*http://www.cisco.com/warp/public/473/lan-switch-transparent.swf

*http://www.cisco.com/warp/public/473/lan-switch-cisco.shtml

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Hub and switch cabling*To create larger networks, connect hubs and switches usingStandard port with special cableSpecial ports with a standard cableStandard port - Medium Dependent Interface-Crossed (MDI-X)Two wires are crossed internallyMedium Dependent Interface (MDI) To see each other as an extension, no signal to be crossedUsing crossover cable between two MDI-X portsTo uncross the internal crossing

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Punch_down panels*Wiring closetshttp://www.youtube.com/watch?v=3wdDRtGLiowLabeling schemes

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http://www.youtube.com/watch?v=ApR7duyTtk0&feature=relatedHow to make cat5e cable : http://www.youtube.com/watch?v=482VtesZwZ8&feature=relatedHow to make wire RJ45 http://www.youtube.com/watch?v=ApR7duyTtk0&feature=related

Routers*Create larger networks by joining two networks segments.Dedicated hardware device or computer systems with more than one network interface and routing software.Routing tableStatic routingDynamic routingUse special routing protocols to pass info to other routers.Distance Vector Routing (RIP) Link state routing (OSPF)

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*Switch and Router Different with routerTypically switch works on lower level (Data link Layer) while Router works in higher level (Network Layer)Algorithms for router and switch about how to forward packers are differentFor example, switch will forward broadcast, so does hub, not router- the address has to be specific.

Routers and Layer 3 Switch*While most switches operate at the Data link layer(layer2), some incorporate features of a router and operate at the network layer (layer3).Layer 3 switches are faster because they are build on switching hardware a router is needed for VLANS communication Why not build a router in the switch itself and do the forwarding in hardwareEX: IP forwarding all in hardwareRoute lookupDecrement the Time to Live (TTL)Recalculation the checksumForward the frame the frame to correct output port

*Can layer 3 switch replace router?No. Layer 3 is good for workgroup and the backbone within an enterprise. But most likely will not replace the router at the edge of the WAN. Routers perform numerous other functions like filtering with access lists, BGP, and so on.

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Gateways*Any device that translate one data format to another is called a gateway. RouterBridgeSoftwareGateway and default gateway

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CSU/DSU*Channel Server Unit/Digital Service Unit ( CSU/DSU) or Data Service UnitConvert digital format on LAN into signal used on WANSit between LAN and access point provided by telecom companyMany routers have CSU/DSU functionality

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Wireless access points*Devices that provide connectivity between wireless LAN devices and in most cases a wired network. AntennaeConvert signal from radio wave or other to that used on the LANs.

*Small wlan can function without access point in so-called ad hoc or peer to peer mode,. Access points support infrastructure mode, which bridges with a wired Ethernet land and also scales the network to support more clients.

Modems*Modulator/Demodulator, convert digital signal generated by computer into analog signals that can travel over conventional phone line. Connect to ISPDialing up to a LANInternal add-in expansion cards or external devices connect to serial or USB portPCMCIA cards for laptopSpeedModem itself Speed of the Universal Asynchronous Receiver/Transmitter (UART) chip, UART 16950 has the speed of 921,600kbp

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Network cards*Called Network Interface Cards (NIC) Attached to external portPC cardInternal Network card System bus compatibilityPeripheral Component Interconnect (PCI)Industry Standard Architecture (ISA)System Resources device conflictMedia compatibilityTwisted pair, coaxial or fiber-optic connection?Driver

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ISDN adapters*Integrated Services Digital Networking (ISDN) is a remote access and WAN technology that can be used in place of a Plain old telephone systems dial-up link Greater speeds than modem, pick up and drop the line considerable faster.Require ISDN terminal adapterAlthough digital signal, different format with the those used on LAN. Create multiple communication channels on a single line.

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System area network cards*Connecting computer systems in a clusterHigh-performance unit.

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MAC addresses*Unique 6-byte address burned info network interface, expressed in hexadecimalNo matter which protocol is used, MAC address is the means by which the network interface is identified on the network.IEEE managing MAC address assignmentIEEE has a system Identifying the manufacturer by looking at the MAC addressDiscover MAC address, depend on the OS

Ifconfig /all on WINDOWs NT/2000Ifconfig a on Linux/UNIX

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*Watch the Intel Gigabit demo.http://www.intel.com/network/connectivity/resources/demos/gigabit/base.swf

*IP: GRE tunnels over IPEmail Generic Routing Encapsulation to encapsulate datagram in an IPv4 tunnel.

IEEE and Networking standards*Institute of Electrical and Electronic Engineers (IEEE) developed a series of networking standardsNetworking technologies developed by manufacturers are CompatibleCabling, networking devices and protocols are all interchangeable under the banner of a specific IEEE

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SpecificationName802.1Internetworking802.2The LLC(Logincal Link Control) sublayer802.3CSMA/CD ( Carrier Sense Multiple Access with Collision Detection) for Ethernet networks802.4A token passing bus802.5Token Ring networks802.6Metropolitan Area Network (MAN)802.7Broadband Technical Advisory Group802.8Fiber-Optic Technical Advisory Group802.9Integrated Voice and Data Networks802.10Standards for Interoperable LAN/MAN Security (SILS) (Network Security)802.11Wireless networks802.12 100Mbps technologies, including 100BASEVG-AnyLAN

*Each of these IEEE specifications outlines specific characteristics for LAN networking including the speed, topology, cabling and access method.

802.3 IEEE standard*Defines characteristics for Ethernet networks.New additions, 802.3u for Fast Ethernet, 802.3z for Gigabit Ethernet, referred to as 802.3x.Speed: Original 10Mbps, Fast Ethernet 100Mbps, Gigabit Ethernet 1000MbpsTopology: bus or star. Media: Coaxial and twisted pair cabling, also fiber optic cable.Access method: CSMA/CD

*Ethernet is by far the most widely implemented form of local area networking.

802.5 IEEE standard*Specifies the characteristics for Token Ring Networks.Introduced by IBM in the mid 80s, network topology of choice until the rise of the popularity of Ethernet.Speed: 4 to 16MbpsTopology: logical ring and most often a physical star. Logical ring is often created in the Multistation Access Unit (MSAU)Media: twisted pair cabling.Access method: token passing.

*When a computer has data to send, it must use a special type of packet known as token. The token travels around the network looking for computers with data to send. The computers data is passed along with the token until it gets to the destination computer. At which point the data is removed from the token and the empty token placed back on the ring.

802.11b IEEE Standard*Specifies the characteristics of wireless LAN Ethernet networks.Special devices called wireless access points to allow communicate.Also connect to wired networks to create wireless portions of entire networks.Speed: 802.11b specifies 11M. Today 802.11g can be 108MbpsMedia: 802.11b standard is 2.4G radio waves.Topology: physical wireless, logical busAccess method: Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA ), a variation of CSMA/CD.

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FDDI*Fiber Distributed Data Interface (FDDI) standard was developed by American National Standards Institute (ANSI)Dual ring technology for fault toleranceSpeed: 100Mbps or higherTopology: dual ring topologyMedia: fiber optic cable, > 2 kilometers. Also possible use copper wire as Copper Distributed Data Interface (CDDI).Access method: token-passing access method

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StandardSpeedPhysical TopologyLogical TopologyMediaAccess Method802.310MbpsBus and StarCoaxial and Twisted pairCSMA/CD(802.3u)100Mbps( Fast Ethernet)StarBusTwisted pairCSMA/CD(802.3z)1000MbpsStarBusTwisted pairCSMA/CD802.54Mbps and 16MbpsStar RingTwisted pairToken passing802.11b11MbpsWirelessBusRadio wavesCSMA/CAFDDI100MbpsDual RingRingFiber-optic Twisted pair/CDDIToken passing

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*To create the complete ring, the Ring In (RI) port on each MASU is connected to the Ring Out (RO) port an another MSAU. The last MASU in the ring is then connected to the first, to complete the ring.

FDDI: Fiber Distributed Data Interface*

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*EMI: is a problem when cables are installed near electrical devices, such as air conditions or fluorescent light fixtures. Crosstalk: refers to how the data signals on two separate media interfere with each other. *Carry signals between computers: Cable-based media and wireless networking.*

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*Cat6 http://www.youtube.com/watch?v=ht8Di4HdyZM*

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*In the world of structured cabling systems the cryptic number 568 refers to the order in which the individual wires inside a CAT 5 cable are terminated. The termination could come at either the users end socket, the patch panel or termination frame or even the individual leads that connect a computer to the wall socket. There are currently two different specifications with respect to the order these cables should be terminated contained in the international standards document (ISO/IEC 11801:1995) as previously mentioned there is no indication as to which of these standards is preferred.

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*Slelecting devices:*http://www2.rad.com/networks/1997/nettut/hub.html*Transparent bridge: forward or block based on MAC

Source route bridge: Used in Token ring network. The entire path is embedded within the packet.

Translational bridge: convert one networking data format to another.

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*CASE: buffer overflowOur switch has a 2G buffer, it connected to all servers, including backup servers. Every night, about 2TB data being backed up. Network was too busy.*

*http://www.cisco.com/warp/public/473/lan-switch-transparent.swf*

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http://www.youtube.com/watch?v=ApR7duyTtk0&feature=relatedHow to make cat5e cable : http://www.youtube.com/watch?v=482VtesZwZ8&feature=relatedHow to make wire RJ45 http://www.youtube.com/watch?v=ApR7duyTtk0&feature=related*

*Can layer 3 switch replace router?No. Layer 3 is good for workgroup and the backbone within an enterprise. But most likely will not replace the router at the edge of the WAN. Routers perform numerous other functions like filtering with access lists, BGP, and so on.*

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*Small wlan can function without access point in so-called ad hoc or peer to peer mode,. Access points support infrastructure mode, which bridges with a wired Ethernet land and also scales the network to support more clients. *

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*IP: GRE tunnels over IPEmail Generic Routing Encapsulation to encapsulate datagram in an IPv4 tunnel. *

*Each of these IEEE specifications outlines specific characteristics for LAN networking including the speed, topology, cabling and access method. *Ethernet is by far the most widely implemented form of local area networking. *When a computer has data to send, it must use a special type of packet known as token. The token travels around the network looking for computers with data to send. The computers data is passed along with the token until it gets to the destination computer. At which point the data is removed from the token and the empty token placed back on the ring. *

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