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

2-36© Copyright 1997, The University of New Mexico

Introduction LAN Technologies

• 10/100/1000 Mbps Ethernet• 100 Mbps FDDI• 155/620 Mbps ATM• 4/10/45 Mbps Wireless