... such as Bus network, Star network, Ring network, Mesh network, Star-bus network, Tree or Hierarchical topology network, ... the logical network topology is

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NETWORKS AND TELECOMMUNICATIONTopic Objective:At the end of this topic students will be able to: Discuss By scale Discuss By connection method Discuss By functional relationship (Network Architectures) Discuss By network topology Discuss By protocol Discuss Common Types Of Computer NetworksDefinition/Overview:Computer Network: A computer network is an interconnected group of computers.Networks may be classified by the network layer at which they operate according to basicreference models considered as standards in the industry, such as the five-layer InternetProtocol Suite model. While the seven-layer Open Systems Interconnection (OSI) referencemodel is better known in academia, the majority of networks use the Internet Protocol Suite(IP).Key Points:1. Computer Networks Classification1.1. By scaleComputer networks may be classified according to the scale: Personal area network(PAN), Local Area Network (LAN), Campus Area Network (CAN), Metropolitan areanetwork (MAN), or Wide area network (WAN). As Ethernet increasingly is the standardinterface for networks, these distinctions are more important to the network administratorthan the user. Network administrators may have to tune the network, to correct delayissues and achieve the desired performance level.1.2. By connection methodComputer networks can also be classified according to the hardware technology that isused to connect the individual devices in the network such as Optical fibre, Ethernet,www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in1www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INWireless LAN, HomePNA, or Power line communication. Ethernets use physical wiringto connect devices. Often they employ hubs, switches, bridges, and/or routers. WirelessLAN technology is built to connect devices without wiring. These devices use a radiofrequency to connect.1.3. By functional relationship (Network Architectures)Computer networks may be classified according to the functional relationships whichexist between the elements of the network, e.g., Active Networking, Client-server andPeer-to-peer (workgroup) architecture.1.4. By network topologyComputer networks may be classified according to the network topology upon which thenetwork is based, such as Bus network, Star network, Ring network, Mesh network, Star-bus network, Tree or Hierarchical topology network, etc. Network Topology signifies theway in which intelligent devices in the network see their logical relations to one another.The use of the term "logical" here is significant. That is, network topology is independentof the "physical" layout of the network. Even if networked computers are physicallyplaced in a linear arrangement, if they are connected via a hub, the network has a Startopology, rather than a Bus Topology. In this regard the visual and operationalcharacteristics of a network are distinct; the logical network topology is not necessarilythe same as the physical layout.1.5. By protocolComputer networks may be classified according to the communications protocol that isbeing used on the network. See the articles on List of network protocol stacks and List ofnetwork protocols for more information. For a development of the foundations ofprotocol design.2. Common Types Of Computer NetworksBelow is a list of the most common types of computer networks in order of scale.2.1. Personal Area Network (PAN)A personal area network (PAN) is a computer network used for communication amongcomputer devices close to one person. Some examples of devices that are used in a PANare printers, fax machines, telephones, PDAs or scanners. The reach of a PAN is typicallywithin about 20-30 feet (approximately 6-9 meters).www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in2www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INPersonal area networks may be wired with computer buses such as USB and FireWire. Awireless personal area network (WPAN) can also be made possible with networktechnologies such as IrDA and Bluetooth.2.2. Local Area Network (LAN)A network covering a small geographic area, like a home, office, or building. CurrentLANs are most likely to be based on Ethernet technology. For example, a library willhave a wired or wireless LAN for users to interconnect local devices (e.g., printers andservers) and to connect to the internet. All of the PCs in the library are connected bycategory 5 (Cat5) cable, running the IEEE 802.3 protocol through a system ofinterconnection devices and eventually connect to the internet. The cables to the serversare on Cat 5e enhanced cable, which will support IEEE 802.3 at 1 Gbit/s.The staff computers can get to the color printer, checkout records, and the academicnetwork and the Internet. All user computers can get to the Internet and the card catalog.Each workgroup can get to its local printer. Note that the printers are not accessible fromoutside their workgroup.All interconnected devices must understand the network layer, because they are handlingmultiple subnets (the different colors). Those inside the library, which have only 10/100Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to thecentral router, could be called "layer 3 switches" because they only have Ethernetinterfaces and must understand IP. It would be more correct to call them access routers,where the router at the top is a distribution router that connects to the Internet andacademic networks' customer access routers.The defining characteristics of LANs, in contrast to WANs (wide area networks), includetheir higher data transfer rates, smaller geographic range, and lack of a need for leasedtelecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operateat speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating thestandardization of 100 Gbit/s, and possibly 40 Gbit/s.2.3. Campus Area Network (CAN)A network that connects two or more LANs but that is limited to a specific andcontiguous geographical area such as a college campus, industrial complex, or a militarybase. A CAN may be considered a type of MAN (metropolitan area network), but isgenerally limited to an area that is smaller than a typical MAN. This term is most oftenused to discuss the implementation of networks for a contiguous area. This should not beconfused with a Controller Area Network.www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in3www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN2.4. Metropolitan Area Network (MAN)A Metropolitan Area Network is a network that connects two or more Local AreaNetworks or Campus Area Networks together but does not extend beyond the boundariesof the immediate town, city, routers, switches & hubs are connected to create a MAN.2.5. Wide Area Network (WAN)A WAN is a data communications network that covers a relatively broad geographic area(i.e. one city to another and one country to another country) and that often usestransmission facilities provided by common carriers, such as telephone companies. WANtechnologies generally function at the lower three layers of the OSI reference model: thephysical layer, the data link layer, and the network layer.2.6. Global Area Network (GAN)Global area networks (GAN) specifications are in development by several groups, andthere is no common definition. In general, however, a GAN is a model for supportingmobile communications across an arbitrary number of wireless LANs, satellite coverageareas, etc. The key challenge in mobile communications is "handing off" the usercommunications from one local coverage area to the next. In IEEE Project 802, thisinvolves a succession of terrestrial Wireless local area networks (WLAN).2.7. InternetworkTwo or more networks or network segments connected using devices that operate at layer3 (the 'network' layer) of the OSI Basic Reference Model, such as a router. Anyinterconnection among or between public, private, commercial, industrial, orgovernmental networks may also be defined as an internetwork.In modern practice, the interconnected networks use the Internet Protocol. There are atleast three variants of internetwork, depending on who administers and who participatesin them:o Intraneto Extraneto Internetwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in4www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INIntranets and extranets may or may not have connections to the Internet. If connected tothe Internet, the intranet or extranet is normally protected from being accessed from theInternet without proper authorization. The Internet is not considered to be a part of theintranet or extranet, although it may serve as a portal for access to portions of an extranet.2.8. IntranetAn intranet is a set of interconnected networks, using the Internet Protocol and uses IP-based tools such as web browsers and ftp tools, that isunder the control of a singleadministrative entity. That administrative entity closes the intranet to the rest of theworld, and allows only specific users. Most commonly, an intranet is the internal networkof a company or other enterprise. A large intranet will typically have its own web serverto provide users with browseable information.2.9. ExtranetAn extranet is a network or internetwork that is limited in scope to a single organizationor entity but which also has limited connections to the networks of one or more otherusually, but not necessarily, trusted organizations or entities (e.g. a company's customersmay be given access to some part of its intranet creating in this way an extranet, while atthe same time the customers may not be considered 'trusted' from a security standpoint).Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type ofnetwork, although, by definition, an extranet cannot consist of a single LAN; it must haveat least one connection with an external network.2.10. InternetA specific internetwork, consisting of a worldwide interconnection of governmental,academic, public, and private networks based upon the Advanced Research ProjectsAgency Network (ARPANET) developed by ARPA of the U.S. Department of Defensealso home to the World Wide Web (WWW) and referred to as the 'Internet' with a capital'I' to distinguish it from other generic internetworks.Participants in the Internet, or their service providers, use IP Addresses obtained fromaddress registries that control assignments. Service providers and large enterprises alsoexchange information on the reachability of their address ranges through the BorderGateway Protocol (BGP).Topic : Network Standardswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in5www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INTopic Objective:At the end of this topic students will be able to: Discuss Standards govern the semantics and syntax of messages Discuss Reliability Discuss Connection-oriented versus connectionless Discuss Hybrid TCP/IP-OSI Architecture Discuss Hybrid TCP/IP-OSI Standards Architecture Discuss Ethernet Discuss Internet Protocol (IP) Discuss Vertical Communication on the Source Host Discuss Vertical Communication on the Destination Host Discuss Not All Devices Have All Layers Discuss OSI Architecture Discuss Other Standards ArchitecturesDefinition/Overview:All networking technologies have standards associated with them. These are usually highlytechnical documents, and often presume that the reader has a fair bit of knowledge aboutnetworking. If you aren't an expert, you will probably have some difficulty understandingnetworking standards. (Some people seem to think I am an expert, but I too have trouble withmost of the details in a typical networking standard.)Key Points:1. OverviewAn Internet Standard is a special Request for Comments (RFC) or set of RFCs. An RFC thatis to become a Standard or part of a Standard begins as an Internet Draft, and is later (usuallyafter several revisions) accepted and published by the RFC Editor as a RFC and labeled aProposed Standard. Later, an RFC is labelled a Draft Standard, and finally a Standard.Collectively, these stages are known as the standards track, and are defined in RFC 2026. Thewww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in6www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INlabel Historic (sic) is applied to deprecated standards-track documents or obsolete RFCs thatwere published before the standards track was established.Only the IETF, represented by the Internet Engineering Steering Group (IESG), can approvestandards-track RFCs. Each RFC is static; if the document is changed, it is submitted againand assigned a new RFC number. If an RFC becomes an Internet Standard (STD), it isassigned an STD number but retains its RFC number. When an Internet Standard is updated,its number stays the same and it simply refers to a different RFC or set of RFCs. A givenInternet Standard, STD n, may be RFCs x and y at a given time, but later the same standardmay be updated to be RFC z instead. For example, in 2007 RFC 3700 was an InternetStandardSTD 1and in May 2008 it was replaced with RFC 5000, so RFC 3700 changed toHistoric status, and now STD 1 is RFC 5000. When STD 1 is updated again, it will simplyrefer to a newer RFC, but it will still be STD 1. Note that not all RFCs are standards-trackdocuments, but all Internet Standards and other standards-track documents are RFCs.In fact, many technologies have quite a number of standards associated with them. Anetworking technology may have more than one standard for any or all of the followingreasons: The original standard has been revised or updated; The technology is sufficiently complex that it needs to be described in more than onedocument; The technology borrows from or builds on documents used in related technologies; More than one organization has been involved in developing the technology.Standards documents created in the United Statesare usually developed in English, but arealso routinely translated into other languages. European standards are often publishedsimultaneously in English, French and German, and perhaps other languages as well.2. Standards govern the semantics and syntax of messages HTTP: Text request and response messages Data field, header, and trailer Header and trailer subdivided into fieldswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in7www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN3. Reliability In TCP, receiver sends ACKs Senders retransmit non-acknowledged segments4. Connection-oriented versus connectionless TCP is connection-oriented HTTP is connectionless5. Hybrid TCP/IP-OSI Architecture OSI is nearly 100% dominant at Layers 1 and 2 TCP/IP is 70% to 80% dominant at Layers 3 and 4 Situation at Layer 5 is complex6. Hybrid TCP/IP-OSI Standards Architecture Application layer (application-to-application) Transport layer (host-to-host) Internet layer (across an internet) Data link layer (across a switched network) Physical layer (between adjacent devices)7. Ethernet Source and destination addresses are 48 bits long Switches forward packets by destination addresses Data field encapsulates an IP packet Unreliable: if detects an error, drops the frame8. Internet Protocol (IP) 32-bit addresses Show 32 bits on each line Unreliable: checks headers for errors but discardswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in8www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN9. Vertical Communication on the Source Host Layer process creates message and then sends the message to the next-lower layer Next-lower layer encapsulates the message in its own message This continues until the final frame at the data link layer10. Vertical Communication on the Destination Host Decapsulation and passing up11. Not All Devices Have All Layers Hosts have all five Routers have only the lowest three Switches have only the lowest two12. OSI Architecture Divides application layer into three layerso Sessiono Presentationo Application13. Other Standards Architectures IPX/SPX SNA AppleTalkTopic : Physical Layer Propagation: Utp And Optical FiberTopic Objective:www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in9www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INAt the end of this topic students will be able to: Discuss Solid-Wire Versus Stranded-Wire UTP Discuss Patch Cords Versus Bulk Wire Discuss Cutting UTP Discuss Stripping the Cord Discuss Putting Wires in Order Discuss Connectorize the Cord Discuss RJ-45 Connector (Side View) Discuss Crimp the Wire into the Connector Discuss Connectorize Both Ends Discuss Test Your CordDefinition/Overview:The propagation speed of a medium refers to the speed that the data travels through thatmedium. Propagation delays differ between mediums, which affect the maximum possiblelength of the Ethernet topology running on that medium.Key Points:1. OverviewThe maximum propagation delay through the network can be calculated by dividing themaximum length by the speed. For 10Base2 thin coax network, this is 185 meters divided by195,000 km/sec, or 950 nanoseconds. If the actual propagation delay from one end of thenetwork to the other is greater than 950 nanoseconds, latecollisions may occur.In the following table, c refers to the speed of light in a vacuum, or 300,000 kilometers persecond.Medium Propagation SpeedThick Coax .77c (231Thin Coax .65c (195Twisted Pair .59c (177Fiber .66c (198www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in10www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INAUI Cable .65c (195Table 1: The Maximum Propagation Delay ThroughThe NetworkFrom these values, the size of a bit on 10BaseT can be calculated. 10BaseT is twisted pair,which has a propagation delay of 177,000 km/sec. 177,000 km/sec divided by 10 million bitsper second is 17.7 meters, or the size of a single bit on a 10BaseT network.2. Solid-WireVersus Stranded-Wire UTP Solid-Wire UTPo Each of the eight wires is a solid wire surrounded by insulationo Solid wires have low attenuation and so can reach 100 meterso Easy to connectorize (add connectors to)o Brittle and easy to break if handled roughly. Not good for runs through open officeareas Stranded-Wire UTPo Each of the eight wires is really several thin strands of wire surrounded byinsulationo Flexible and rugged: ideal for running around an office areao Higher attenuation than solid-wire UTP so can only be used in short runsup to about10 meters3. Patch Cords Versus Bulk Wire Patch Cordso Cut to popular lengths and connectorized at the factorywww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in11www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INo Tested for qualityo Use stranded-wire UTP, which is sufficiently rugged for open office areaso TIA/EIA-568 specifies patch cords for the run from the wall jack to the desktopbecause it is rugged and flexible Bulk Wireo Comes in spools of 50 meters or moreo Can be cut to precise lengths needed to connect deviceso Solid-wire UTP for longer distance and to make connectorization easiero Cut, connectorized, and tested by the user, by the organization, or by a LANinstaller4. Cutting UTP Cut a desired length of UTP Make it a little longer than you needo Adding a connector can take a few incheso If the connectorization doesnt test well, you will have to cut the end and install anew connectoro UTP cord should never be pulled tautly; it can beak if subjected to pulls. Should beslack after installation5. Stripping the Cord You must strip the jacket 3 to 5 cm (1 to 2 inches) at each end Stripper scores the jacket (cuts into the jacket without cutting through it) to avoid damagingthe wires inside the jacket Stripper is rotated once around the cord to score it evenlywww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in12www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN The tip of the cord is pulled off after the scoring, exposing 3 to 5 cm (one to two inches) ofthe wires6. Putting Wires in Order There are orange, green, blue, and brown pairs Each pair has one wire with solid-color insulation and one wire that is white with bands ofthe pairs color These wires will be placed in a particular order in the RJ-45 connector There are two popular color schemes in TIA/EIA-568o T568A and T568Bo T568B is the most commonly used color scheme in the United States we will use it Note that T568A is a part of the TIA/EIA-568 standard, as is T568B7. Connectorize the Cord Cut the wires straight across so that no more than 1.25 cm (a half inch) of wires are exposedfrom the jacketo This controls terminal cross-talk interference Be sure to cut straight across or the wires will not all reach the pins when you push them intothe connector in the next step!8. RJ-45 Connector (Side View) Hold the RJ-45 connector away from you (with the hole in the back toward you) and thespring clip down Insert your wires into the connector, white-orange on left Push the wires all the way to the end Examine the Connectoro Are the wires in the correct order?www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in13www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INo Hint: as a rough first check, the 1st, 3rd, 5th, and 7th wires from the left should bemostly whiteo If not, reinsertthem in the correct order9. Crimp the Wire into the Connector Get a good crimper Cheap ones often fail to make a good connection Should have a ratchet for tightening without breaking the connector Press down to make a good connection. If you press too lightly, the connection will not work Crimping forces the pins on the front of the RJ-45 connector though the insulation, into eachwireo Insulation displacementconnection (IDC) This also crimps the cord at the back end of the connector for strain relief to keep the cordfrom pulling out if the cord is pulled10. Connectorize Both Ends White-orange is on the left (in Pin 1) at BOTH ENDS of the cordo You do not reverse the order at the other end!11. Test Your Cord After you have connectorized both ends, test your cord Misconnection is very common, so every cord must be checked Inexpensive continuity testers make sure wires are connected electrically and in the rightorder Expensive performance testers test for the quality of propagation Continuity Testero Test for wires being in right slots and making good contacto Place connectors of cord into two endswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in14www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INo Hit Test buttono Did it work? If It Didnt Worko Be sure you understand the problemo If an open connection, one or more of the wires was not pushed all the way to theend or the crimping did not push the pin all the way through the insulation. Nexttime, cut the wires straight across and crimp very firmlyo If miswired, see where it was miswiredo Cut off theends of the cord and reconnectorize Signal Testerso Expensive testerso Test for signal qualityo Test for breaks with time domain reflectometry (TDR), which sends signals andlooks for reflections that indicate breaks.In Section 2 of this course you will cover these topics:Ethernet LansWireless LansTopic : Ethernet LansTopic Objective:www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in15www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INAt the end of this topic students will be able to: Discuss Ethernet Standards Setting Discuss Physical Layer Standards Discuss Ethernet MAC Layer Standards Discuss Ethernet MAC Layer Standards Discuss Switch Purchasing Considerations Discuss Advanced Switch Purchasing ConsiderationsDefinition/Overview:Ethernet: Ethernet was developed by the Xerox Corporation's Palo Alto Research Centre(known colloquially as Xerox PARC) in 1972 and was probably the first true LAN to beintroduced.Key Points:1. OverviewIn 1985, the Instituteof Electrical and Electronic Engineers (IEEE) in the United States ofAmerica, produced a series of standards for Local Area Networks (LANs) called the IEEE802 standards. These have found widespread acceptability and now form the core of mostLANs. One of the IEEE 802 standards, IEEE 802.3, is a standard known as "Ethernet". Thisis the most widely used LAN technology in the world today. Although IEEE 802.3 differssomewhat from the original standard (the "blue book" defined in September 1980) it is verysimilar, and both sets of standards may be used with the same LAN.The IEEE standards have been adopted by the International Standards Organisation (ISO),and is standardised in a series of standards known as ISO 8802-3. ISO was created in 1947 toconstruct world-wide standards for a wide variety of Engineering tasks. Adoption of ISOstandards allows manufacturers to produce equipment which is guarented to operateanywhere it is finally used. ISO standards tend to be based on other standards (such as thoseproduced by the IEEE), the only problem is that the ISO standards tend to be issued later, andare therefore less up to date.The simplest form of Ethernet uses a passive bus operated at 10 Mbps. The bus is formedfrom a 50 Ohm co-axial cable which connects all the computers in the LAN. A single LANmay have up to 1024 attached systems, although in practice most LANs have far fewer. Onewww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in16www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INor more pieces of coaxial cable are joined end to end to create the bus, known as an "EthernetCable Segment". Each segment is terminated at both ends by 50 Ohm resistors (to preventreflections from the discontinuity at the end of the cable) and is also normally earthed at oneend (for electrical safety). Computers may attach to the cable using transceivers and networkinterface cards.Frames of data are formed using a protocol called Medium Access Control (MAC), andencoded using Manchesterline encoding. Ethernet uses a simple Carrier-Sense MultipleAccess protocol with Collision Detection (CSMA/CD) to prevent two computers trying totransmit at the same time (or more correctly to ensure both computers retransmit any frameswhich are corrupted by simultaneous transmission).100 Mbps networks may operate full duplex (using a Fast Ethernet Switch) or half duplex(using a Fast Ethernet Hub). 1 Gbps networks usually operate between a pair of EthernetSwitches. (N.B.It is not possible to have a dual-speed hub, since a hub does not store andforward frames, however a number of manufacturers sell products they call "dual-speedhubs". In fact, such devices contain both a 10 Mbps and a 100 Mbps hubs, interconnected bya store-and-forward bridge.)Ethernet LANs may be implemented using a variety of media (not just the coaxial cabledescribed above). The types of media segments supported by Ethernet are: 10B5 Low loss coaxial cable (also known as "thick" Ethernet) 10B2 Low cost coaxial cable (also known as "thin" Ethernet) 10BT Low cost twisted pair copper cable (also known as Unshielded Twisted Pair (UTP),Category-5) 10BF Fibre optic cable 100BT Low cost twisted pair copper cable (also known as Unshielded Twisted Pair (UTP),Category-5) 100BF Fibre Fast Ethernet 1000BT Low cost twisted pair copper cable (also known as Unshielded Twisted Pair (UTP),Category-5) 1000BF Fibre Gigabit Ethernet 10000BT Category 6 (Unshielded Twisted Pair (UTP), Category-6) 10000BT Fibre 10 Gigabit Ethernetwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in17www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INThe network design rules for 10 Mbps using these types of media are summarized below:Segment type Max Number ofsystems per cablesegmentMax Distance of acable segment10B5 (Thick Coax) 100 500 m10B2 (Thin Coax) 30 185 m10BT (Twisted Pair) 2 100 m10BFL (Fibre Optic) 2 2000 mTable 1: Network Design Rules for Different types of CableThere is also a version of Ethernet which operates fibre optic links at 40 Gbps and at 100Gbps. Many LANs combine the various speeds of operation using dual-speed switches whichallow the same switch to connect some ports to one speed of network, and other ports atanother speed. The higher speed ports are usually used to connect switches to one another.2. Ethernet Standards Setting 802.3 Working Group Physical and data link layer standards OSI standards3. Physical Layer Standards BASE means baseband 100BASE-TX dominates for access lines 10GBASE-SX dominates for trunk lines Link aggregation for small capacity increases Regeneration to carry signals across multiple switches4. Ethernet MAC Layer Standards Data link layer subdivided into the LLC and MAC layers The Ethernet MAC Layer Frameo Preamble and Start of Frame Delimiter fieldswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in18www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INo Destination and Source MAC addresses fields Hexadecimal notationo Length fieldo Data field LLC subheader Packet PAD if neededo Frame Check Sequence field5. Ethernet MAC Layer Standards Switch operationo Operation of a hierarchy of switches Single possible path between any two computers Hierarchy gives low price per frame transmitted Single points of failure and the Spanning Tree Protocolo VLANs and frame tagging to reduce broadcastingo Momentary traffic peaks: addressed by overprovisioning and priorityo Hubs and CSMA/CD6. Switch Purchasing Considerations Number and speed of ports Switching matrix (nonblocking) Store-and-forward versus cut-through switcheswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in19www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN Managed switches Ethernet securityo 802.1X Port-Based Access Controlo 802.1AE MACsec7. Advanced Switch Purchasing Considerations Physical size Fixed-Port-Speeches Stackable Switches Modular Switches Chassis Switches Pins in SwitchPorts and Uplink Ports Electrical Power (802.3af)Topic : Wireless LansTopic Objective:At the end of this topic students will be able to: Discuss Benefits Of Wireless LANs Discuss Local Wireless Technologies Discuss Radio Propagation Discuss Radio Propagation Discuss 802.11 Operation Discuss 802.11 WLAN Security Discuss WLAN Management Discuss BluetoothDefinition/Overview:www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in20www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INWireless LAN: A wireless LAN or WLAN is a wireless local area network, which is thelinking of two or more computers or devices without using wires. WLAN utilizes spread-spectrum or OFDM modulation technology based on radio waves to enable communicationbetween devices in a limited area, also known as the basic service set. This gives users themobility to move around within a broad coverage area and still be connected to the network.Key Points:1. OverviewThe popularity of wireless LANs is a testament primarily to their convenience, costefficiency, and ease of integration with other networks and network components. Themajority of computers sold to consumers today come pre-equipped with all necessarywireless LAN technology.For the home user, wireless has become popular due to ease of installation, and locationfreedom with the gaining popularity of laptops. Public businesses such as coffee shops ormalls have begun to offer wireless access to their customers; some are even provided as a freeservice. Large wireless network projects are being put up in many major cities. Google iseven providing a free service to Mountain View, California and has entered a bid to do thesame for San Francisco. New York City has also begun a pilot program to cover all fiveboroughs of the city with wireless Internet access.2. Benefits Of Wireless LANsThe benefits of wireless LANs include: Convenience: The wireless nature of such networks allows users to access network resourcesfrom nearly any convenient location within their primary networking environment (home oroffice). With the increasing saturation of laptop-style computers, this is particularly relevant. Mobility: With the emergence of public wireless networks, users can access the internet evenoutside their normal work environment. Most chain coffee shops, for example, offer theircustomers a wireless connection to the internet at little or no cost.www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in21www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN Productivity: Users connected to a wireless network can maintain a nearly constant affiliationwith their desired network as they move from place to place. For a business, this implies thatan employee can potentially be more productive as his or her work can be accomplished fromany convenient location. Deployment: Initial setup of an infrastructure-based wireless network requires little morethan a single access point. Wired networks, on the other hand, have the additional cost andcomplexity of actual physical cables being run to numerous locations (which can even beimpossible for hard-to-reach locations within a building). Expandability: Wireless networks can serve a suddenly-increased number of clients with theexisting equipment. In a wired network, additional clients would require additional wiring. Cost: Wireless networking hardware is at worst a modest increase from wired counterparts.This potentially increased cost is almost always more than outweighed by the savings in costand labor associated to running physical cables.3. Local Wireless Technologies 802.11 for Corporate WLANs Bluetooth for PANs Ultrawideband (UWB) RFIDs ZigBee Mesh Networks4. Radio Propagation Frequencies and Channels Antennas Propagation Problemso Inverse square law attenuationo Dead spots / shadow zoneswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in22www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INo Electromagnetic interferenceo Multipath interferenceo Attenuation and shadow zone problems increase with frequency5. Radio Propagation Shannons Equation and the Importance of Channel Bandwidtho C = B Log2(1+S/N) WLANs use unlicensed Radio Bands Spread Spectrum Transmission to Reduce Propagation Problemso FHSS (up to 4 Mbps)o DSSS (up to 11 Mbps)o OFDM (up to 54 Mbps)o MIMO (100 Mbps to 600 Mbps)6. 802.11 Operation Wireless Access PointBridge to the Main Wired Ethernet LANo To reach servers and Internet access routerso Transfers packet between 802.11 and 802.3 frames Need for Media Access Control (Box)o CSMA/CA and RTS/CTSo Throughput is aggregate throughput Bandswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in23www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INo 2.4 GHz band: Only 3 channels, lower attenuationo 5 GHz band: Around 24 channels, higher attenuationo More channels means less interference between nearby access points Standardso 802.11b: 11 Mbps, DSSS, 2.4 GHz bando 802.11a: 54 Mbps, OFDM, 2.4 GHz bando 802.11g: 54 Mbps, OFDM, 5 GHz bando 802.11n: 100 Mbps 600 Mbps, MIMO, Dual-Band7. 802.11 WLAN Security Wardrivers and Drive-By Hackers Core Securityo WEP (Unacceptably Weak)o WPA (Lightened form of 802.11i)o 802.11i (The gold standard today)o 802.1X and PSK modes for WPA and 802.11i Rogue Access Points and Evil Twin Access Points8. WLAN Management Surprisingly Expensive Access Point Placemento Approximate layoutwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in24www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INo Site survey for more precise layout and power Remote Access Point Managemento Smart access points or WLAN switches and dumb access points9. Bluetooth PANs Cable Replacement Technology Limited Speeds and Distance Application Profiles UWB in the Future?In Section 3 of this course you will cover these topics:TelecommunicationsWide Area Networks WansTopic : TelecommunicationsTopic Objective:At the end of this topic students will be able to: Discuss Modulation Discuss Channels Discuss Networks Discuss Analogue or digitalDefinition/Overview:www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in25www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INTelecommunication: Telecommunication is the assisted transmission of signals over adistance for the purpose of communication. In earlier times, this may have involved the useof smoke signals, drums, semaphore, flags, or heliograph. In modern times,telecommunication typically involves the use of electronic transmitters such as the telephone,television, radio or computer. Early inventors in the field of telecommunication includeAntonio Meucci, Alexander Graham Bell, Guglielmo Marconi and John Logie Baird.Telecommunication is an important part of the world economy and the telecommunicationindustry's revenue has been placed at just under 3 percent of the gross world product.Key Points:1. OverviewA telecommunication system consists of three basic elements: A transmitter that takes information and converts it to a signal; A transmission medium that carries the signal; and, A receiver that receives the signal and converts it back into usable information.For example, in a radio broadcast the broadcast tower is the transmitter, free space is thetransmission medium and the radio is the receiver. Often telecommunication systems are two-way with a single device acting as both a transmitter and receiver or transceiver. Forexample, a mobile phone is a transceiver.Telecommunication over a phone line is called point-to-point communication because it isbetween one transmitter and one receiver. Telecommunication through radio broadcasts iscalled broadcast communication because it is between one powerful transmitter andnumerous receivers.2. Analogue or digitalSignals can be either analogue or digital. In an analogue signal, the signal is variedcontinuously with respect to the information. In a digital signal, the information is encoded asa set of discrete values (for example ones and zeros). During transmission the informationcontained in analogue signals will be degraded by noise. Conversely, unless the noiseexceeds a certain threshold, the information contained in digital signals will remain intact.This noise resistance represents a key advantage of digital signals over analogue signals.www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in26www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN3. NetworksA collection of transmitters, receivers or transceivers that communicate with each other isknown as a network. Digital networks may consist of one or more routers that routeinformation to the correct user. An analogue network may consist of one or more switchesthat establish a connection between two or more users. For both types of network, repeatersmay be necessary to amplify or recreate the signal when it is being transmitted over longdistances. This is to combat attenuation that can render the signal indistinguishable fromnoise.4. ChannelsA channel is a division in a transmission medium so that it can be used to send multiplestreams of information. For example, a radio station may broadcast at 96.1 MHz whileanother radio station may broadcast at 94.5 MHz. In this case, the medium has been dividedby frequency and each channel has received a separate frequency to broadcast on.Alternatively, one could allocate each channel a recurring segment of time over which tobroadcastthis is known as time-division multiplexing and is sometimes used in digitalcommunication.5. ModulationThe shaping of a signal to convey information is known as modulation. Modulation can beused to represent a digital message as an analogue waveform. This is known as keying andseveral keying techniques exist (these include phase-shift keying, frequency-shift keying andamplitude-shift keying). Bluetooth, for example, uses phase-shift keying to exchangeinformation between devices.Modulation can also be used to transmit the information of analogue signals at higherfrequencies. This is helpful because low-frequency analogue signals cannot be effectivelytransmitted over free space. Hence the information from a low-frequency analogue signalmust be superimposed on a higher-frequency signal (known as a carrier wave) beforetransmission. There are several different modulation schemes available to achieve this (twoof the most basic being amplitude modulation and frequency modulation). An example of thisprocess is a DJ's voice being superimposed on a 96 MHz carrier wave using frequencymodulation (the voice would then be received on a radio as the channel 96 FM).www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in27www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INTopic : Wide Area Networks WansTopic Objective:At the end of this topic students will be able to: Discuss Virtual Private Networks (PVCs) Discuss Other PSDNs Discuss Frame Relay PSDNs Discuss Public Switched Data Networks Discuss Leased Line Networks Discuss WANsDefinition/Overview:Wide Area Network: Wide Area Network (WAN) is a computer network that covers a broadarea (i.e., any network whose communications links cross metropolitan, regional, or nationalboundaries ).Key Points:1. OverviewWide Area Network (WAN) are less formally, a network that uses routers and publiccommunications links .Contrast with personal area networks (PANs), local area networks(LANs), campus area networks (CANs), or metropolitan area networks (MANs) which areusually limited to a room, building, campus or specific metropolitan area (e.g., a city)respectively. The largest and most well-known example of a WAN is the Internet.www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in28www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INWANs are used to connect LANs and other types of networks together, so that users andcomputers in one location can communicate with users and computers in other locations.Many WANs are built for one particular organization and are private. Others, built byInternet service providers, provide connections from an organization's LAN to the Internet.WANs are often built using leased lines. At each end of the leased line, a router connects tothe LAN on one side and a hub within the WAN on the other. Leased lines can be veryexpensive. Instead of using leased lines, WANs can also be built using less costly circuitswitching or packet switching methods. Network protocols including TCP/IP delivertransport and addressing functions. Protocols including Packet over SONET/SDH, MPLS,ATM and Frame relay are often used by service providers to deliver the links that are used inWANs. X.25 was an important early WAN protocol, and is often considered to be the"grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 arestill in use today (with upgrades) by Frame Relay.Academic research into wide area networks can be broken down into three areas:Mathematical models, network emulation and network simulation. Performanceimprovements are sometimes delivered via WAFS or WAN Optimization.Transmission rate usually range from 1200 bits/second to 6 Mbit/s, although someconnections such as ATM and Leased lines can reach speeds greater than 156 Mbit/s. Typicalcommunication links used in WANs are telephone lines, microwave links & satellitechannels.Recently with the proliferation of low cost of Internet connectivity many companies andorganizations have turned to VPN to interconnect their networks, creating a WAN in thatway. Companies such as Cisco, New Edge Networks and Check Point offer solutions tocreate VPN networks.Option: Description Advantages Disadvantages BandwidthrangeSampleprotocolsusedLeasedlinePoint-to-Pointconnection betweentwo computers orLocal AreaNetworks (LANs)Most secure Expensive PPP,HDLC,SDLC,HNASwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in29www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INCircuitswitchingA dedicated circuitpath is createdbetween end points.Best example isdialup connectionsLessExpensiveCall Setup 28 Kb/s -144 Kb/sPPP,ISDNPacketswitchingDevices transportpackets via ashared single point-to-point or point-to-multipoint linkacross a carrierinternetwork.Variable lengthpackets aretransmitted overPermanent VirtualCircuits (PVC) orSwitched VirtualCircuits (SVC)Shared mediaacross linkX.25Frame-RelayCell relay Similar to packetswitching, but usesfixed length cellsinstead of variablelength packets.Data is divided intofixed-length cellsand thentransported acrossvirtual circuitsbest forsimultaneoususe of Voiceand dataOverhead canbe considerableATMTable 1 : Several options are available for WAN connectivity2. WANs Wide Area Networkswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in30www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INo Carry data between different sites, usually within a corporationo High-cost and low-speed lines 128 kbps to a few megabits per secondo Carrierso Purposes Internet access, site-to-site connections, and remote access forIndividualso Technologies Leased line networks, public switched data networks, and virtual privatenetworks3. Leased Line Networks Leased Lines are Long-Term Circuitso Point-to-Pointo Always Ono High-speeds Device at Each Siteo PBX for leased line voice networkso Router for leased line data networks Pure Hub-and-Spoke, Full Mesh, and Mixed Topologies Many Leased Line Speedso Fractional T1, T1, and bonded T1 dominatewww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in31www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INo Slowest leased lines run over 2-pair data-grade UTPo Above 3 Mbps, run over optical fibero Below about 3 Mbps, 2-pair data grade UTPo Above 3 Mbps, optical fibero North American Digital Hierarchy, CEPT, and other standards below 50 Mbpso SONET/SDH above 50 Mbpso Symmetrical DSL lines with QoS4. Public Switched Data Networks PSDNso Services offered by carrierso Customer does not have to operate or manageo One leased line per site from the site to the nearest POPo By reducing corporate labor, typically cheaper than leased line networkso Service Level Agreementso Virtual circuits5. Frame Relay PSDNs Frame Relayo Most popular PSDNo 56 kbps to about 40 Mbpso Access devices, CSU/DSUs, leased access lines, POP ports, virtual circuits,managementwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in32www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN Usually POP port speed charges are the biggest cost component Second usually are PVC chargeso Leased line must be fast enough to handle the speeds of all of the PVCs multiplexedover it6. Other PSDNs ATMo High speed and costo Cell switchingo Low use Metro Etherneto Extending Ethernet to MANso Very attractive speeds and priceso Small but growing rapidly Carrier IP Networkso Essentially, private Internets with QoS and securityo Carriers want to use it to replace Frame Relay7. Virtual Private Networks (PVCs) The Internet is inexpensive and universalo VPNs add security to transmission over the Internet (or any other untrustednetwork)www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in33www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN IPseco The strongest security for VPNso Tunnel mode between sites is inexpensiveo Transport mode between computers is expensive SSL/TLSo First for browser communication with a single webservero SSL/TLS gateways make it a full remote access VPNIn Section 4 of this course you will cover these topics:Tcp/Ip InternetworkingSecurityTopic : Tcp/Ip InternetworkingTopic Objective:At the end of this topic students will be able to: Discuss Layer 3 Switches Discuss Port Numbers and Sockets in TCP and UDP Discuss The User Datagram Protocol (UDP), Transmission Control Protocol (TCP) , InternetProtocol (IP) and Internet Control Message Protocol (ICMP) Discuss Domain Name System (DNS)www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in34www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN Discuss Multiprotocol Label Switching Discuss Address Resolution Protocol and Dynamic Routing Protocols Discuss Routing Decisions and Routing of Packets Discuss Router Operation Discuss Hierarchical IP Address parts Discuss InternetworkingDefinition/Overview:The Internet evolved from the ARPANET , an early wide-area network developed by theUSmilitary for military and academic communication. Amongst the design aims was theability to provide a scalable internetwork of heterogeneous networks. The result was theTCP/IP-based Internet, which is based on several fundamental principles: Hosts in the Internet are identified by unique (32-bit) addresses assigned by a number ofcentral authorities. The address consists of a network part and a host part. All hosts on thesame network have the same network part to their address, but unique host parts. Clearly, ahost which is connected to more than one network (called a multi-homed host) has more thanone address. A drawback of this approach is that moving hosts between networks requirestheir addresses to be changed. On the other hand, the approach has numerous advantages thatmore than compensate for this. Interconnection among networks is provided by multi-homed hosts called gateways or routers(a firewall is a special type of gateway). A gateway relays network traffic between two ormore networks. These networks may have further gateways, resulting in further relaying. Toreduce the amount of information needed by gateways, decisions about where to relay traffic(called routing decisions) are based on the network part of the destination address; the hostpart is only used to route traffic once it reaches the destination network. All networks are treated equally. LANs, WANs and point-to-point links are each separatenetworks and are treated in a uniform fashion.The network protocol used for transferring traffic across the Internet is IP (Internet Protocol),and the 32-bit addresses are known as IP addresses.Key Points:www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in35www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN1. OverviewThe TCP/IP model is a specification for computer network protocols created in the 1970s byDARPA, an agency of the United States Department of Defense. It laid the foundations forARPANET, which was the world's first wide area network and a predecessor of the Internet.The TCP/IP Model is sometimes called the Internet Reference Model, the DoD Model or theARPANET Reference Model.The TCP/IP Suite defines a set of rules to enable computers to communicate over a network.TCP/IP provides end to end connectivity specifying how data should be formatted, addressed,shipped, routed and delivered to the right destination. The specification defines protocols fordifferent types of communication between computers and provides a framework for moredetailed standards.TCP/IP is generally described as having four abstraction layers (five if the bottom physicallayer is included). The layer view of TCP/IP is based on the seven-layer OSI ReferenceModel written after the original TCP/IP specifications, and is not officially recognized.Regardless, it provides an analogy for understanding the operation of TCP/IP, andcomparison of the models is common.The TCP/IP model and related protocols are currently maintained by the Internet EngineeringTask Force (IETF).An early architectural document, RFC 1122, emphasizes architectural principles overlayering. End-to-End Principle: This principle has evolved over time. Its original expression put themaintenance of state and overall intelligence at the edges, and assumed the Internet thatconnected the edges retained no state and concentrated on speed and simplicity. Real-worldneeds for firewalls, network address translators, web content caches and the like have forcedchanges in this Principle. Robustness Principle: "Be liberal in what you accept, and conservative in what you send.Software on other hosts may contain deficiencies that make it unwise to exploit legal butobscure protocol features".www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in36www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INEven when the layers are examined, the assorted architectural documentsthere is no singlearchitectural model such as ISO 7498, the OSI reference modelhave fewer, less rigidlydefined layers than the commonly referenced OSI model, and thus provides an easier fit forreal-world protocols. In point of fact, one frequently referenced document does not contain astack of layers. The lack of emphasis on layering is a strong difference between the IETF andOSI approaches. It only refers to the existence of the "internetworking layer" and generally to"upper layers"; this document was intended as a 1996 "snapshot" of the architecture: "TheInternet and its architecture have grown in evolutionary fashion from modest beginnings,rather than from a Grand Plan. While this process of evolution is one of the main reasons forthe technology's success, it nevertheless seems useful to record a snapshot of the currentprinciples of the Internet architecture."No document officially specifies the model, another reason to deemphasize the emphasis onlayering. Different names are given to the layers by different documents, and differentnumbers of layers are shown by different documents.There are versions of this model with four layers and with five layers. RFC 1122 on HostRequirements makes general reference to layering, but refers to many other architecturalprinciples not emphasizing layering. It loosely defines a four-layer version, with the layershaving names, not numbers, as follows: Process Layer or Application Layer: this is where the "higher level" protocols such as SMTP,FTP, SSH, HTTP, etc. operate. Host-To-Host (Transport) Layer: this is where flow-control and connection protocols exist,such as TCP. This layer deals with opening and maintaining connections, ensuring thatpackets are in fact received. Internet or Internetworking Layer: this layer defines IP addresses, with many routing schemesfor navigating packets from one IP address to another. Network Access Layer: this layer describes both the protocols (i.e., the OSI Data Link Layer)used to mediate access to shared media, and the physical protocols and technologiesnecessary for communications from individual hosts to a medium.The Internet protocol suite (and corresponding protocol stack), and its layering model, werein use before the OSI model was established. Since then, the TCP/IP model has beencompared with the OSI model numerous times in topics, which often results in confusionwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in37www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INbecause the two models use different assumptions, including about the relative importance ofstrict layering.2. Internetworking Internetworking involves the internet and transport layers Packets are encapsulated in frames in single networks. Transport layer is end-to-end Internet layer is hop-by-hop between routers IP, TCP, and UDP are the heart of TCP/IP internetworking3. Hierarchical IP Address parts Network, subnet, and host parts4. Router Operation Border routers connect networks Internal routers connect subnets We focused on TCP/IP routing, but multiprotocol routing is crucial Router meshes give alternative routes, making routing very expensive5. Routing of Packets Routing tables IP address range governed by a rowusually a route to a network or subnet Metric to help select best matches Next-hop router to be sent the packet nexto Can be a local host on one of the routers subnets Processo Final all possible routes through row matchingo Select by length of match, then metric if tieo Send out to next-hop router in the best-match rowwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in38www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN6. Detailed Look at Routing Decisions IP address rangeo Destinationo Masko If the masked destination IP address in an arriving packet matches the destinationvalue, the row is a match Next-Hop Routero Interfaceo Next-hop router or destination host7. Dynamic Routing Protocols Interior dynamic routing protocols within an autonomous systemo RIP, OSPF, EIGRP Exterior dynamic routing protocols between autonomous systemso BGP8. Address Resolution Protocol Router knows the IP address of the next-hop router or destination host Must learn the data link layer address as well9. Multiprotocol Label Switching Routing decisions are based on labels rather than destination IP addresses Reduces routing costswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in39www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN10. Domain Name System (DNS) General hierarchical naming system for the Internet11. Internet Control Message Protocol (ICMP) General supervisory protocol at the internet layer Error advisements and Pings (echo requests/replies)12. The Internet Protocol (IP) Detailed look at key fields Protocol field lists contents of the data field 32-bit IP addresses IPv4 is the current version IPv6 offers 128-bit IP addresses to allow many more IP addresses to serve the world13. The Transmission Control Protocol (TCP) Sequence and acknowledgement numbers Flag fields that are set or not set Window size field allows flow control Options are common Three-way openings (SYN, SYN/ACK, and ACK) Four-way normal closings (FIN, ACK, FIN, ACK) One-way abrupt closing (RST)14. The User Datagram Protocol (UDP) Simple four-field header15. Port Numbers and Sockets in TCP and UDP Applications get well-known port numbers on servers Connections get ephemeral port numbers on clients Socket is an IP address, a colon, and a port number This designates a specific application (or connection) on a specific server (or client)www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in40www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN16. Layer 3 Switches Fast, inexpensive, and limited routersTopic : SecurityTopic Objective:At the end of this topic students will be able to: Discuss Cryptographic Systems Discuss Firewalls Discuss Security Management Discuss The Threat Environment Discuss Attributes of a secure network Discuss Comparison with computer securityDefinition/Overview:Network security: Network security consists of the provisions made in an underlyingcomputer network infrastructure, policies adopted by the network administrator to protect thenetwork and the network-accessible resources from unauthorized access and the effectiveness(or lack) of these measures combined together.Key Points:1. Comparison with computer securitySecuring network infrastructure is like securing possible entry points of attacks on a countryby deploying appropriate defense. Computer security is more like providing means to protecta single PC against outside intrusion. The former is better and practical to protect the civiliansfrom getting exposed to the attacks. The preventive measures attempt to secure the access toindividual computers--the network itself--thereby protecting the computers and other sharedwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in41www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INresources such as printers, network-attached storage connected by the network. Attacks couldbe stopped at their entry points before they spread. As opposed to this, in computer securitythe measures taken are focused on securing individual computer hosts. A computer hostwhose security is compromised is likely to infect other hosts connected to a potentiallyunsecured network. A computer host's security is vulnerable to users with higher accessprivileges to those hosts.2. Attributes of a secure networkNetwork security starts from authenticating any user, most likelyan username and apassword. Once authenticated, a state firewall enforces access policies such as what servicesare allowed to be accessed by the network users. Though effective to prevent unauthorizedaccess, this component fails to check potentially harmful contents such as computer wormsbeing transmitted over the network. An intrusion prevention system (IPS) helps detect andprevent such malware. IPS also monitors for suspicious network traffic for contents, volumeand anomalies to protect the network from attacks such as denial of service. Communicationbetween two hosts using the network could be encrypted to maintain privacy. Individualevents occurring on the network could be tracked for audit purposes and for a later high levelanalysis.Honeypots, essentially decoy network-accessible resources, could be deployed in a networkas surveillance and early-warning tools. Techniques used by the attackers that attempt tocompromise these decoy resources are studied during and after an attack to keep an eye onnew exploitation techniques. Such analysis could be used to further tighten security of theactual network being protected by the honeypot.3. The Threat Environment Many threats Malware: viruses versus worms, payloads, etc. Social engineering Spam, credit card theft, identity theft, adware, spyware Human Break-Inswww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in42www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.INo Definition of hackingauthorizationo Scanning phase; the exploito After the Break-in: deleting log files, backdoors, damage at leisure Human attackso Denial-of-Service (DoS) Attack with zombieso Bots Traditional attackerso Hackers, virus writers, script kiddieso Disgruntled employees and ex-employees Criminal attackers now dominate on the Internet Cybercrime and cyberwar4. Security Management Security is a management issue, not a technical issue Comprehensive security and centralized management Defense in depth Enumerating and prioritizing assetso Asset control plans: authentication, authorization, and auditing Authenticationo Applicant and verifier Central authentication server for consistencyo Password authentication Poor password discipline is commonwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in43www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN Passwords need to be long and complexo Biometrics Fingerprint, iris, face, etc. Error rates and deceptiono Digital certificate authentication Public key / private key pairs, digital certificates The strongest form of authentication Need both an applicant calculation and a digital certificate forauthorization5. Firewalls Filter, drop, or pass incoming and outgoing packets Stateful inspection firewallso Default rules for connection-opening attemptso ACLs to modify the default ruleso Other packetsaccept if part of connection Firewalls, IDSs and IPSs IPSs have the strongest filtering ability6. Cryptographic Systems To protect streams of messages Initial authentication Message-by-message protections: encryption for confidentiality, digital signature forauthentication and message integrity Symmetric key encryptionwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in44www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN Public key encryptiono Hardening Clients and Serverso Vulnerability Testingo Incident Response Detecting the attack, stopping the attack, repairing the damage, punishingthe attacker Major attacks and CSIRTs Disasters and disaster recoveryIn Section 5 of this course you will cover these topics:Network ManagementNetworked ApplicationsTopic : Network ManagementTopic Objective:At the end of this topic students will be able to: Discuss Network Simulation Discuss IP Subnetting Discuss Directory Servers Discuss Configuring Routers Discuss Network Management Utilities Discuss Simple Network Management Protocol (SNMP)www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in45www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN Discuss Traffic ManagementDefinition/Overview:Network management: Network management refers to the activities, methods, procedures,and tools that pertain to the operation, administration, maintenance, and provisioning ofnetworked systems.Key Points:1. OverviewFunctions that are performed as part of network management accordingly include controlling,planning, allocating, deploying, coordinating, and monitoring the resources of a network,network planning, frequency allocation, predetermined traffic routing to support loadbalancing, cryptographic key distribution authorization, configuration management, faultmanagement, security management, performance management, bandwidth management, andaccounting management.A large number of access methods exist to support network and network device management.Access methods include the SNMP, Command Line Interfaces (CLIs), custom XML, CMIP,Windows Management Instrumentation (WMI), Transaction Language 1, CORBA, netconf,and the Java Management Extensions - JMX.Schemas include the WBEM and the Common Information Model amongst others.Data for network management is collected through several mechanisms, including agentsinstalled on infrastructure, synthetic monitoring that simulates transactions, logs of activity,sniffers and real user monitoring. In the past network management mainly consisted ofmonitoring whether devices were up or down; today performance management has become acrucial part of the IT team's role which brings about a host of challenges -- especially forglobal organizations. Operation deals with keeping the network (and the services that the network provides) up andrunning smoothly. It includes monitoring the network to spot problems as soon as possible,ideally before users are affected.www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in46www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN Administration deals with keeping track of resources in the network and how they areassigned. It includes all the "housekeeping" that is necessary to keep the network undercontrol. Maintenance is concerned with performing repairs and upgrades - for example, whenequipment must be replaced, when a router needs a patch for an operating system image,when a new switch is added to a network. Maintenance also involves corrective andpreventive measures to make the managed network run "better", such as adjusting deviceconfiguration parameters. Provisioning is concerned with configuring resources in the network to support a givenservice. For example, this might include setting up the network so that a new customer canreceive voice service.2. Network Simulation Study before you install equipment There is a process to follow What Is versus What If3. IP Subnetting Must balance number of subnets with number of hosts per subnet A part with N bits can support 2N-2 subnets or hosts4. Directory Servers Centralized storage of information Hierarchical organization LDAP is the protocol for data queries5. Configuring Routers Cisco IOS command line interface (CLI) Worked through a simple example6. Network Management Utilities Diagnose a network connection for a client PCwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in47www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN7. Simple Network Management Protocol (SNMP) Protocol for managing network devices remotely Manager, managed device, agent, RMON probe Management information base (MIB) SNMP messages: commands and responses, traps8. Traffic Management Overprovisioning Priority QoS reservations Traffic shaping: prevent congestion from occurringTopic : Networked ApplicationsTopic Objective:At the end of this topic students will be able to: Discuss Application Architectures Discuss E-Mail Discuss HTTP and HTML Discuss E-Commerce Discuss Software as a Service (SAS)Definition/Overview:Network applications: Network applications are simply the things networks are used for.Key Points:www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in48www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN1. OverviewThere are many ways we can classify and talk about network applications, for example: Who created the application content? Is the content created by users, a company running aWeb site, a third party? Who creates the content on MySpace? Who creates the content onAmazon? An increasing proportion of Internet content is created by users. How much did it cost to create and deliver the content? An email is nearly free. A studiomovie or recording is quite expensive. The Internet is disrupting many industries by bringingthe cost of content creation and delivery down rapidly. Who was the application intended for? The general public? A small group with a commoninterest? An individual? What was the content creator's goal? To sell something? To teach? To persuade? How is the application paid for? Subscription? One time sales? Advertising? Is the application on the public Internet or a restricted-access intranet or extranet?Type Definition ExampleInternet a global, public TCP/IP network used by over abillion peopleSending email to a friendIntranet a TCP/IP network with access restricted tomembers or employees of a single organizationAccessing your record in theemployee personnel fileExtranet a TCP/IP network with access restricted tomembers or employees of a two or moreorganizationsChecking availability ofinventory from an outsidesupplierTable 1: Client-Server Applications That Use The TCP/IPCommunication Protocols2. Application Architectures Terminal-host Client/servero File server program accesso Client/server processing with request/response cycle Peer-to-peer (P2P)www.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in49www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN Evolution of architectures driven by growing desktop computer power3. E-Mail Sending: Simple Mail Transfer Protocol (SNMP) Retrieving: POP and IMAP Document format standards: RFC 822/2822, HTML, and UNICODE Viruses, worms, and Trojan horseso Where to do antivirus filtering? Spam4. HTTP and HTML Webpages consist of an HTML document and multiple graphics, etc. files Message transfer: HTTPo Multiple downloads for the multiple files in a webpage MIME5. E-Commerce E-Commerce : webservice with additional functionality Webserver interacts with customer browser Application server interacts with back-end databases, passes webified response to thewebserver for delivery to the customer DMZ and SSL/TLS security6. Software as a Service (SAS) Regular webservice: retrieve stored files SAS: use HTTP and extended HTML to handle program-to-program interactions on differentmachines SOAP request message passes parameters to a service object on another machinewww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in50www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN SOAP response message brings the reply SOAP messages are written in XMLwww.bsscommunitycollege.in www.bssnewgeneration.in www.bsslifeskillscollege.in51www.onlineeducation.bharatsevaksamaj.net www.bssskillmission.inWWW.BSSVE.IN


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