lecture #3 - uses of networks. network architecture - network hardware prof. boyanov
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Lecture #3 - Uses of Networks. Network Architecture - Network Hardware prof. Boyanov. C o n t e n t s Terminology Application of the Computer Networks Network Hardware Network Types. 3. 4. 9. 13. Text book of the course. Our new Bible:. Introduction - Terminology prof. Boyanov. - PowerPoint PPT PresentationTRANSCRIPT
Lecture #3 - Uses of Networks. Lecture #3 - Uses of Networks. Network Architecture - Network Network Architecture - Network
HardwareHardwareprof. Boyanovprof. Boyanov
C o n t e n t s C o n t e n t s TerminologyTerminology Application of the Computer NetworksApplication of the Computer Networks Network HardwareNetwork Hardware Network TypesNetwork Types
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Text book of the courseText book of the course
Our new Bible:Our new Bible:
Introduction - Introduction - TerminologyTerminology
prof. Boyanovprof. Boyanov
Computer Network:Computer Network:interconnected autonomous computersinterconnected autonomous computers
explicit addressing and namingexplicit addressing and naming virtualvirtual
explicit allocation / reallocationexplicit allocation / reallocation memorymemoryexplicit remote managementexplicit remote management
Distributed System:Distributed System:interconnected autonomous computersinterconnected autonomous computers
transparent addressingtransparent addressing virtualvirtualtransparent allocation and reallocationtransparent allocation and reallocation
uniprocessoruniprocessortransparent executiontransparent execution
Application of the Application of the Computer NetworksComputer Networks
Enterprise Networks (Intranets) Enterprise Networks (Intranets) Public NetworksPublic Networks Personal UsePersonal Use
Social AspectsSocial Aspects
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Resource SharingResource Sharing - many computers in - many computers in different placesdifferent places
High ReliabilityHigh Reliability - duplication of data, - duplication of data, hardware resources, fault-tolerancehardware resources, fault-tolerance
Low Cost/Performance RatioLow Cost/Performance Ratio - cheaper - cheaper workstations than mainframes; application workstations than mainframes; application of the of the client-server modelclient-server model
Scalability and FlexibilityScalability and Flexibility - system - system grows with the enterprise grows with the enterprise
Enterprise Networks Enterprise Networks (“(“IntranetsIntranets”)”)
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Public NetworksPublic Networks
2 preconditions2 preconditions: cheap and compact home : cheap and compact home computers and communication technologiescomputers and communication technologies
Electronic commercial and banking, Electronic commercial and banking, entertainment, public and social services, entertainment, public and social services, mass media etc.mass media etc.
Person-to-person communicationPerson-to-person communication Instances: WWW, E-mail, electronic Instances: WWW, E-mail, electronic
newspapers, on-line TV/Radio, newsgroups, newspapers, on-line TV/Radio, newsgroups, videoconferencing etc. videoconferencing etc.
Personal UsePersonal Use Moving all the services at home - Moving all the services at home -
shopping, banking, health, shopping, banking, health, TV/radio/cinema/news-papers etc.TV/radio/cinema/news-papers etc.
On-line information - “Browsing”, On-line information - “Browsing”, “Surfing”, searching machines.“Surfing”, searching machines.
Personal contacts and communication.Personal contacts and communication.
Social IssuesSocial Issues Formal (Legislative) Regulation of service Formal (Legislative) Regulation of service
providing (incl. taxes, QoS/protection of providing (incl. taxes, QoS/protection of customer rights, registration of customer rights, registration of sites/addressing etc.)sites/addressing etc.)
Electronic Payments and Security IssuesElectronic Payments and Security Issues Advertisement (incl. Internet, Advertisement (incl. Internet,
“spaming”/“bombing”)“spaming”/“bombing”) Information CorrectnessInformation Correctness Public control (illegal sex, trade, crimes)Public control (illegal sex, trade, crimes)
Clinton’s Communication Decency Act - 1996
Network HardwareNetwork Hardware Main Taxonomy Dimensions:Main Taxonomy Dimensions:
transmission technologytransmission technology
network range (scale, size)network range (scale, size) Transmission TechnologyTransmission Technology
broadcast networksbroadcast networks
point-to pointpoint-to point
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Broadcast NetworksBroadcast Networks Single communication channel shared by Single communication channel shared by
all the machines in the networkall the machines in the network Short messages (packets) with addressing Short messages (packets) with addressing
fieldfield Target machine interprets current Target machine interprets current
message; the rest ignore itmessage; the rest ignore it Special bits in the address field indicate the Special bits in the address field indicate the
transmission mode: transmission mode: broadcastbroadcast (to all the (to all the machines); machines); multicastmulticast (to group of (to group of machines)machines)
Point-to-point Point-to-point NetworksNetworks
Many connections between pairs of Many connections between pairs of machinesmachines
Packets visit 0, 1, 2 … intermediate Packets visit 0, 1, 2 … intermediate machines reaching the target onemachines reaching the target one
Alternative routes Alternative routes -- routing algorithms routing algorithms
Basically for large networksBasically for large networks
Network RangeNetwork Range Physical SizePhysical Size
Data Flow Machines & Multicomputers Data Flow Machines & Multicomputers are are Distributed SystemsDistributed Systems but notbut not Computer Computer NetworksNetworks
Local Area Networks (LANs)Local Area Networks (LANs) Metropolitan Area NetworksMetropolitan Area Networks Wide Area Networks (WANs)Wide Area Networks (WANs) Internetworks (connection of more than Internetworks (connection of more than
one network - The Internet) one network - The Internet)
fine grain parallel com-puters; many functional units
perform any instruction
message passing sys-tems; short and fast com-
munication busses
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Local Area Networks Local Area Networks (LANs)(LANs)
Up to 1-2 km physical range (room, Up to 1-2 km physical range (room, building, campus)building, campus)
Private owned (companies, branches, Private owned (companies, branches, laboratories, small institutions)laboratories, small institutions)
Connect PCs, workstations, disk stores, Connect PCs, workstations, disk stores, printers and other peripherals printers and other peripherals
Main characteristics:Main characteristics:sizesizetransmission technologytransmission technologytopologytopology 16
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Size of the LANsSize of the LANs Small, technologically restricted sizeSmall, technologically restricted size
Bounded and known transmission timeBounded and known transmission time
Simple network management due to the Simple network management due to the
limited transmission time limited transmission time
Transmission Transmission Technology of the LANsTechnology of the LANs
Usually based on a single cable attaching Usually based on a single cable attaching
all the components of the networkall the components of the network
Communication speed 10 - 100 Mb/S, 1+ Communication speed 10 - 100 Mb/S, 1+
Gb/sGb/s
Communication delay 10 - 100 Communication delay 10 - 100 S S (1 (1 s = s =
1010-6-6 S) S)
Topology of the LANsTopology of the LANs
Topology is the graph of the connectivity of the Topology is the graph of the connectivity of the network componentsnetwork components
Typical topology of LANs is bus or ringTypical topology of LANs is bus or ring Bus topology is based on linear cableBus topology is based on linear cable Arbitration management - time-sharing control: Arbitration management - time-sharing control:
1 master machine at any instant is allowed to 1 master machine at any instant is allowed to transmit; conflict requests resolvationtransmit; conflict requests resolvation
Centralized or Distributed arbitrationCentralized or Distributed arbitration EthernetEthernetTMTM (IEEE 802.3) standard: bus-based, (IEEE 802.3) standard: bus-based,
distributed arbitration based on collision distributed arbitration based on collision detection and random delay for next attemptdetection and random delay for next attempt
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Topology of the LANs - Topology of the LANs - ring topologyring topology
Network ring forms necklace of the Network ring forms necklace of the
workstationsworkstations
Bit-slice propagation of the packetsBit-slice propagation of the packets
IBM IBM Token RingToken Ring (IEEE 802.5) standard (IEEE 802.5) standard
operates at 4-16 Mb/Soperates at 4-16 Mb/S
Local area networksLocal area networks•Local area networks (LANs) are physically relatively
small. They are usually spanning one km or less. •Usually, every device on the LAN essentially shares the
same transmission cable. This is called shared media access.•Ethernet LAN technology (IEEE 802.3) has today the
largest installed base. It has several types of cabling - Thick coaxial (10-base-5) with AUI connectors and transceivers, thin coaxial (10-base-2) with BNC connectors, and unshielded twisted pair (UTP or 10-base-T) with RJ-45 jacks. •Each station on an Ethernet has an Ethernet network
interface card (NIC), which has a special hardware address, assigned to guarantee link layer uniqueness, even across vendors.•Ethernet is mostly used with speeds 10 Mbps and 100 Mbps.
Local area networksLocal area networks• Ethernet media access control allows any station on the network try to transmit at any time, which may produce collisions when several stations transmit at one time. • Media access mechanism identifies collisions and allows each station to have adequate access to common channel.• In Ethernet this mechanism is called carrier sense multiple access with collision detection (CSMA/CD).• Another quite a popular LAN technology is the Token Ring specified in IEEE 802.5 with basic speed of 4 Mbps. • The media access in Token Ring is based on token passing mechanism.• Other IEEE 802.x standards are 802.4 Token Bus (5 and 10 Mbps) used in Manufacturing Automation Protocol (MAP) systems, and 802.6 Metropolitan Area Network (MAN), which is also called DQDP (Distributed Queue Dual Bus) and has speed 100 Mbps.
Metropolitan Area Metropolitan Area NetworksNetworks
Bigger version of LANs using similar Bigger version of LANs using similar technology - common broadcast media technology - common broadcast media that connects all the computersthat connects all the computers
Options: voice and image Options: voice and image communications (incl. cable TV)communications (incl. cable TV)
No switching elements; 1 - 2 cablesNo switching elements; 1 - 2 cables DQDB (Distributed Queue Dual Bus - DQDB (Distributed Queue Dual Bus -
IEEE 802.6) Standard: 2 unidirectional IEEE 802.6) Standard: 2 unidirectional buses with 2 head-ends (for each bus) buses with 2 head-ends (for each bus) to initiate the transmission activity in to initiate the transmission activity in each direction.each direction. 1/4
Wide Area Networks Wide Area Networks (WANs)(WANs)
WAN covers large geographic area (country, WAN covers large geographic area (country, continent)continent)
Connects different types of machines - Connects different types of machines - ““hostshosts” via communication ” via communication subnetsubnet
Separation of the services: hosts run Separation of the services: hosts run application programs and subnet performs application programs and subnet performs the connection tasksthe connection tasks
Subnet consists of Subnet consists of transmission linestransmission lines and and switching elementsswitching elements (“ (“routersrouters”: ”: specialized in connecting 2 or more specialized in connecting 2 or more switching lines)switching lines)
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WANs & Routers WANs & Routers
Router is specialized switching element in Router is specialized switching element in the WAN subnet. the WAN subnet.
SwitchingSwitching is the process of: is the process of:1) receiving data on the incoming channel[s]; 1) receiving data on the incoming channel[s];
2) interpreting it;2) interpreting it;
3) choosing an outgoing line and 3) choosing an outgoing line and
4) forwarding the data on it.4) forwarding the data on it. Typical structure of WAN: hosts connected Typical structure of WAN: hosts connected
by LANs; LANs connected by the subnetby LANs; LANs connected by the subnet
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WANs & SubnetsWANs & Subnets Subnet consists of routers and connection linesSubnet consists of routers and connection lines The subnet lines are based on cables The subnet lines are based on cables
(telephone lines) that connects pairs of routers (telephone lines) that connects pairs of routers ((point-to-pointpoint-to-point network) in a connected graph. network) in a connected graph. ExceptionException: : wirelesswireless//satellitesatellite based subnets based subnets are of broadcast type (for WANs specialized in are of broadcast type (for WANs specialized in broadcasting communication)broadcasting communication)
Non connected routers communicate via Non connected routers communicate via intermediate routers in intermediate routers in store-and-forwardstore-and-forward modemode
Subnet topology - usually irregularSubnet topology - usually irregular 1/6
Wide area networksWide area networksWide area network (WANWide area network (WAN) is a concept ) is a concept
that is used in context of geographically that is used in context of geographically large networks (1 - 50 km span). large networks (1 - 50 km span).
Generally, WANs consist of site specific Generally, WANs consist of site specific LANs and teleoperator backbones which are LANs and teleoperator backbones which are used to interconnect the LANs. used to interconnect the LANs.
This trunk capacity is provided to WANs as:This trunk capacity is provided to WANs as:– Basic analogue telephone connection with modemsBasic analogue telephone connection with modems– Digital ISDN connection with terminal adapters (TA)Digital ISDN connection with terminal adapters (TA)– PDH based connection with direct router support or using Frame PDH based connection with direct router support or using Frame
Relay (FR)Relay (FR)– SDH based connection with ATM.SDH based connection with ATM.
Wide area networksWide area networksBasic telephone networks support switched 64 kbps Basic telephone networks support switched 64 kbps
connections with either analogue modem or digital connections with either analogue modem or digital ISDN subscriber lines.ISDN subscriber lines.
ISDN Basic Rate InterfaceISDN Basic Rate Interface (BRI) (BRI) consists of two consists of two bearer (B) channels and a 16 Kbps signaling (D) bearer (B) channels and a 16 Kbps signaling (D) channel (called as 2 B + D).channel (called as 2 B + D).
ISDN Primary Rate InterfaceISDN Primary Rate Interface (PRI) (PRI) is a high- is a high-bandwidth version of the BRI, also called as 30 B + D.bandwidth version of the BRI, also called as 30 B + D.
Serial Line Internet Protocol (SLIP)Serial Line Internet Protocol (SLIP) and and Point-Point-to-Point Protocolto-Point Protocol
(PPP)(PPP) are used with the basic analogue and digital are used with the basic analogue and digital telephone interfaces as the transport layer for an telephone interfaces as the transport layer for an Internet link. Internet link.
SLIP/PPP connections are temporary links over SLIP/PPP connections are temporary links over standard serial phone links between end user and standard serial phone links between end user and terminal server.terminal server.
Wireless NetworksWireless Networks
Preconditions: mobile computers Preconditions: mobile computers ++ digitaldigital wireless communications wireless communications
Application: portable office, Application: portable office, transportation business, emergency transportation business, emergency services, police/ military, etc. services, police/ military, etc.
Features:Features: easy installation, portabilityeasy installation, portabilitylow capacity (1-2 Mb/S), low security, low capacity (1-2 Mb/S), low security,
high error rate + radio pollutionhigh error rate + radio pollution Wired-Wireless Networking ConvergenceWired-Wireless Networking Convergence TendenciesTendencies
Laptops, PDAsbinary coded radio transmission orCDPD (Cellular Digital Packet Data)
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InternetworksInternetworks Internetwork = Communication Internetwork = Communication
between LANs, MANs and WANs with between LANs, MANs and WANs with different internal standardsdifferent internal standards
Compatibility requires Compatibility requires gatewaysgateways Typical architecture: collection of LANs Typical architecture: collection of LANs
connected by a WAN: connected by a WAN: (WAN (WAN differs from the subnet just by differs from the subnet just by presence of hosts besides the routers)presence of hosts besides the routers)
The InternetThe Internet = biggest internetwork = biggest internetwork connecting universities, public and connecting universities, public and private offices, persons etc. private offices, persons etc.
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