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2-1© Copyright 1997, The University of New Mexico
Definitions
• Architecture• Proprietary Systems• De facto Standards• Standards
2-2© Copyright 1997, The University of New Mexico
Definitions
• Architecture:– The science, art, or profession of designing and
constructing buildings, bridges, etc.– Any framework, system, etc.– The design and interaction of components of a
computer or computer systems
2-3© Copyright 1997, The University of New Mexico
Definitions
• Proprietary Systems– Privately owned and operated– Held under patented, trademark, or copyright by a
private person or company
• De facto Standards– Existing or being such in actual fact though not by legal
establishment– Official recognition
• Standards– Something established for use as a rule or basis of
comparison in measuring or judging capacity, quantity, content, extent, value, quality, etc.
2-4© Copyright 1997, The University of New Mexico
Definitions
• Rules and conventions for the exchange of information– Open Systems
• Who makes the rules and conventions?– Many local, regional, and international organizations– ISO, ITU, IEEE, ANSI, ECMA
2-5© Copyright 1997, The University of New Mexico
Definitions
• Open Systems Interconnection Standards– Packet Switched Public Data Network (PSPDN)– Circuit Switched Public Data Network (CSPDN)– Public Switched Telephone Network (PSTN)– Integrated Services Digital Network (ISDN)– Local Area Network (LAN)
2-6© Copyright 1997, The University of New Mexico
Definitions
• V-series– Connecting equipment to a Public Switched Telephone
Network (PSTN)
• X-series– Connecting equipment to a Public Switched Data
Network (PSDN)
• I-series– Connecting equipment to an Integrated Services Digital
Network (ISDN)
2-7© Copyright 1997, The University of New Mexico
Internetworking Architecture Models
• OSI Model • 3-Layer Model• TCP/IP Model
2-8© Copyright 1997, The University of New Mexico
OSI Model
• International Organization for Standardization (ISO)– Open System Interconnection (OSI) Model, provides a
frameworkApplication
Presentation
Session
Transport
Network
Data Link
Physical
Boundary
Technology independent
Technology dependent
2-9© Copyright 1997, The University of New Mexico
OSI Model
• Physical Layer (1)– deals with mechanical, electrical and procedural
interfacing– provides collision detection– specifies cables, connectors, and other components– transmits raw information over communication channel– establishes, maintains, and disconnects physical links– includes software device drivers for communication
interfaces
2-10© Copyright 1997, The University of New Mexico
OSI Model
• Data Link Layer (2)– provides reliable transfer of data– breaks data (packets) into frames– adds bits for error detection/correction– manages access to and use of the channel– solve problems caused by lost, damaged, and duplicate
frames– sends acknowledgments– adds flags to indicate beginning and end of message– connectionless or connection oriented services– IEEE MAC and LLC support
2-11© Copyright 1997, The University of New Mexico
OSI Model
• Network Layer (3)– establishes, maintains and terminates connections– determines how packets are routed– divides transport messages into packets and
reassembles them– performs congestion control, flow control– provides virtual circuit or datagram services– recognizes message priorities– sends messages in proper order– handles internetworking
2-12© Copyright 1997, The University of New Mexico
OSI Model
• Transport Layer (4)– establishes reliable end-to-end transport session (error
detection and recovery), once path has been established
– fragmentation of message into packets (if not handled by layer 3)
– multiplexing of several sessions from same source and all going to same destination
– creates distinct network connections– monitors quality of service– disassembles and assembles session messages– flow control (if not done by layer 3)
2-13© Copyright 1997, The University of New Mexico
OSI Model
• Session Layer (5)– establishes and controls system-dependent issues– establishes and terminates connections– accounting service– user interface into the network– authentication of users– controls dialogue, organizes and synchronizes
2-14© Copyright 1997, The University of New Mexico
OSI Model
• Presentation Layer (6)– data encryption, security, compression and code
conversion– make sure data is encoded in standard form (ASCII)– handles pass-through of services from session to
application layer
2-15© Copyright 1997, The University of New Mexico
OSI Model
• Application Layer (7)– login, password check– agreement on semantics for information exchange– file transfer, access and management– message handling, email– job transfer and manipulation– directory service– system management– industry protocols– database access and management– virtual terminals
2-16© Copyright 1997, The University of New Mexico
OSI Model
Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
Physical
Data
Physical
2-17© Copyright 1997, The University of New Mexico
3-Layer Model
• 7-layer OSI to 3-layer mapping– System integrators approach
Application
Presentation
Session
Transport
Network
Data Link
Physical
Network Services
Network Protocols
Network Infrastructure
2-18© Copyright 1997, The University of New Mexico
TCP/IP Model
• TCP/IP Protocol Suite, ARPANET (DARPA)
Application
Transport (TCP,UDP)
Internet (IP)
Network Access
Physical
2-19© Copyright 1997, The University of New Mexico
OSI to TCP/IP Models
• 7-layer OSI and TCP/IP Protocol Architectures
Application
Presentation
Session
Transport
Network
Data Link
Physical
Transport (TCP,UDP)
Network Access
Application
Internet (IP)
Physical
2-20© Copyright 1997, The University of New Mexico
Internetworking Standards
• Proprietary Systems• De facto Standards• Standards Based Solutions
2-21© Copyright 1997, The University of New Mexico
Internetworking Standards
• Proprietary Systems– Hewlett-Packard– DARPA TCP/IP– Sun Network Services– Novell NetWare– IBM/SNA– DEC/DECnet Phase IV– 3Com– Xerox/XNS– IBM/SNA– Apple/AppleTalk– Banyan VINES
2-22© Copyright 1997, The University of New Mexico
Internetworking Standards
• De facto Standards– TCP/IP– Ethernet V1 & V2– X-Windows– Unix– WIN95– NT
2-23© Copyright 1997, The University of New Mexico
Internetworking Standards
• Standards Based Solutions– IEEE: 802.3/CSMA/CD, 802.5/Token Ring, 802.2/LLC,
etc.– ANSI: FDDI, etc.– CCITT: V.35, X.25, Frame Relay, etc.– ISO-ITU: 8802/3, 8802/5, 9314, V.35, etc.– EIA: RS-232, RS-449, etc.– ATM Forum
2-24© Copyright 1997, The University of New Mexico
Network Terminology
• Modems: OSI-Layer 1 device. Modulator-demodulator, device that converts digital and analog signals, allows data to be transmitted over voice grade telephone lines (PSTN). Modem standards include: V.21, V.22 bis, V.32 bis, V.34, V.42 bis, etc.
• Repeaters: OSI-Layer 1 device. Regenerates and propagates electrical signals between two network segments. Repeater standards include: Ethernet, IEEE 802.3 (10Base5, 10Base2, 10BaseT, 10BaseFX), FDDI, ATM, etc.
2-25© Copyright 1997, The University of New Mexico
Network Terminology
• Bridges: OSI Layer 2 device. Connects and passes packets between network segments that use similar and different communication protocols. Bridge standards include: IEEE 802.1d, Transparent Source Routing, Translational, etc.
• Switches: OSI Layer 2 device. Very fast bridge. Switch Standards include: ATM, Frame Relay, SMDS, ISDN, etc.
2-26© Copyright 1997, The University of New Mexico
Network Terminology
• Routers: OSI Layer 3 device. Forwards packets from one network to another based on metrics that will allow for optimum path. Router standards include: RIP, OSPF, ISIS, BGP, EGP, etc.
• Gateways: OSI Layers 1-7 device. Special-purpose device that converts information from one protocol stack to another.
2-27© Copyright 1997, The University of New Mexico
Network Terminology
• 4 types of equipment– Repeaters - layer 1– Bridges - layer 2– Routers - layer 3– Gateways - layers 1-7
• All use functionality of lower layers
2-28© Copyright 1997, The University of New Mexico
Repeaters
• Used to extend a LAN• Connects two cable segments• Amplifies and sends all electrical signals
between segments• Stations do not know whether a
repeater separates them• IEEE 802.3: max. 4 repeaters between
any two stations
2-29© Copyright 1997, The University of New Mexico
Repeaters
repeater
max. Ethernet segment max. Ethernet segment
direct connection
2-30© Copyright 1997, The University of New Mexico
Bridges
• Simplest form to extend a LAN• LANs can be of more than one type• Interconnect LAN and MAN• Past: used between LANs with identical
protocols (physical, MAC)• Present: used between LANs with
different protocols
© Copyright 1997, The University of New Mexico 2-31
Bridges
bridgestations stations
standard connection(same as computers)
2-32© Copyright 1997, The University of New Mexico
Switches
• Switched LAN, single electronic device that transfers frames among many stations
• Hub: simulates a single shared medium– at most two computers can communicate at a time– max. possible bandwidth is R (rate a single computer
can send data)
2-33© Copyright 1997, The University of New Mexico
Switches
• Switch: simulates a bridged LAN with one station per segment– each computer is in a simulated LAN segment– as many as 1/2 of stations can send data at the same
time (1/2 send, 1/2 receive)– max. possible bandwidth is RN/2, N is number of
stations connected
2-34© Copyright 1997, The University of New Mexico
Introduction to Transmission Media & LAN Technologies
• Transmission Media & Cabling Systems• LAN Technologies
2-35© Copyright 1997, The University of New Mexico
Introduction to Transmission Media
• Signals• Data Transmission• Transmission Media• Cabling Systems