Chapter 5 Local Area Network Concepts and Architecture

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Chapter 5Local Area Network Concepts and
Architecture

• Network Fundamentals
• Local Area Network (LAN)
• Open Systems Interconnection (OSI)
• LAN Architectures

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Network Fundamentals

• Definitions
• Classifications
• Network topology
• Network types
• Local Area Network

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Definition

• Network
• Backbond network

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Classification

• Topology
• Ownership
• Geography
• Transmission

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Network Topology

• Star
• Hierarchical
• Mesh
• Bus
• Ring
• Hybrid

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Star Network

• Usage
• Centralized processing or communication
• Pros
• Expansion
• Implementation
• No limit to no. and length of arms
• Cons
• Single point of failure
• Overload of mater during peak traffic

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Hierarchical Network

• Usage
• Distributed processing
• Tree structure with a root
• pro
• No single point of failure

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Mesh Network

• Web structure
• Usage
• Public telephone system
• Pro
• Alternative communication route
• Con
• Line cost

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Bus Network

• Usage
• Date entry or office environment
• Pros
• Independent between nodes
• High reliability
• Cons
• Limited number of attached device
• Hard to locate the problems

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Ring Network

• Usage
• Manufacturing
• Pros
• Less attenuation
• Error control
• Network management
• Cons
• Failing of a node

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Hybrid Networks

• Usage
• Connecting different networks
• Pro
• Communication between networks
• Con
• Conversion device and costs
• Compatibility

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Network Ownership

• Private networks
• Public networks
• Valued added networks

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Private networks

• Full control
• Special needs
• Expense

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Public networks

• Controlled by carriers
• Regulated by government
• Inexpensive

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Valued Added Networks

• Functions
• Code translation
• Speed conversion
• Store message and delivery
• Examples
• Telex
• SWIFT
• SITA (airline)
• IVAN (insurance)

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Networks by Geography

• Wide area network (WAN)
• Metropolitan area network (MAN) 30 miles
• Local area network (LAN) 5 miles

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LAN Characteristics

• Limited distance within a few miles
• High data rate - 2 to 1000Mbps
• Low error rate
• Good response time
• Private owned
• No regulation
• Share hardware, software, and data files

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Business Needs

• Corporate asset for competitive edge
• Data accessibility (information distribution)
• Less expenses
• Better service - response time and reliability
• Higher productivity
• Control or secure

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LAN Analysis Design

• Meet business objectives (strategic planning)
• Prevent technological obsolescence

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LAN Hardware Software

• Hardware
• PC servers and clients
• Network interface card (NIC) physical address
• Media or Cables
• Unshielded twisted pair (inexpensive)
• Coaxial cable (faster, expensive)
• Optical fiber (fastest, expensive)
• Air for wireless
• Hub (compatible)
• connect wires and cables, repeater, error
  detection
• Software network operating system

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Open System Interconnection Model

• International Standards Organization
• Interconnection of dissimilar network
• Seven Layers
• Application
• Presentation
• Session
• Transport
• Network
• Data Link
• Physical

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Application Layer

• Utilities support end-user application program
• Determine data to be send at originating end
• Process data at receiving end

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Presentation Layer

• Change data format
• Compression/expansion
• Encryption/decryption

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Session Layer

• Communication rules of machines or application
  programs
• Accounting functions

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Transport Layer

• Identify receiving address
• Flow control rate of transmission
• Recovery calculate and check checksum of entire
  message

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Network Layer

• Route message
• Dissemble and assemble data (packets)
• Accounting functions

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Data Link Layer

• By IEEE 802
• Establish link between two ends
• Detect and correct transmission error
• Add header and trailer
• Divide data unit for transmission (frames)
• Sublayers
• Media access control (MAC) token ring or
  Ethernet
• Logical link control (LLC) assembling and
  disassembling frames, error control, flow control

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Physical Layer

• Electrical, mechanical, procedural specifications
  for data transmission
• Hardware specification by RS-232-C

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Other Concepts

• Protocol
• Encapsulation/ de-encapsulation

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Standards

• IEEE 802.2 LLC protocol
• IEEE 802.3 CSMA/CD baseband bus
• IEEE 802.4 token passing bus
• IEEE 802.5 token passing ring
• Fiber Distributed Data Interface (FDDI) Standard

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LAN Architecture Model

• Network architecture includes
• Access methodology
• Logical topology
• Physical topology
• Network configuration includes
• Network architecture
• Media choice

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Access Methods

• Contention carrier sense multiple access with
  collision detection (CSMA/CD)
• Inexpensive NIC
• For office application
• Not for manufacturing due to inconsistent
  response time
• Token passing 24 bits of token (free or busy)
• More efficient at higher network utilization rate
• More expensive NIC
• Supported by IBM

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Topology

• Logical
• Sequential
• Broadcast
• Physical
• Bus line broken
• Ring PC or NIC broken
• Star (hub, concentrator, MAU (multistation access
  unit, repeater, switching hub) single point of
  failure

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Ethernet

• Functionality
• Access method CSMA/CD
• Logical topology broadcast
• Physical topology bus or star
• Ethernet II
• Header (preamble) for synchronizing
• Destination source address (MAC layer address)
• Type field for network protocol
• Data field
• Frame check sequence (FCS) CRC-32
• IEEE 802.3 replace type field with length field

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Media-related Ethernet

• 10BaseT
• 10Base2 (Thinet with RG-58 coax)
• 10Base5 (thick coaxial cable RG-11)
• 100BaseT Fast Ethernet with 100-Mbps
• 100BaseTX (2 pair of Category 5 UTP or 1 pair of
  Type 1 STP)
• 100BaseT4 (4 pair of Category 3, 4, or 5 UTP)
• 100BaseFX (fiber optic cable)
• Trade off between speed and maximum network
  diameter
• Gigabit Ethernet (1000Base-X)

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Token Ring

• Functionality
• Access method token passing
• Logical topology sequence
• Physical topology ring or star
• IEEE 802.5
• Starting delimiter alert NIC about token
  approaching
• Access control field (1 for busy, 0 for free)
• Frame control field indicate regular data or
  network management frame
• Destination source address (MAC layer address)
• Routing information field for multiple token ring
  LANs
• Data field
• Frame check sequence (FCS) CRC-32
• Ending delimiter (ending or intermediate frame)
• Frame status field for successful delivery

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Fiber Distributed Data Interface

• Fiber distributed data interface (FDDI) by
  American National standard Institute (ANSI)
• Functionality
• Access method Modified token passing
• Logical topology sequential
• Physical topology dual counter-rotating rings
• Build-in reliability and longer distance
• Single-attachment stations (SAS) or
  dual-attachment stations (DAS)

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Fiber Distributed Data Interface

• High speed backbone between LANs
• Primary ring and secondary ring - 100Mbps token
  ring
• Fault tolerance
• High-priority station having longer access time
• Maximum 500 stations
• Maximum length of 200 kilometers (rings)
• Maximum 2 kilometers between stations
• Constant data rate for video and voice

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Fiber Distributed Data Interface

• Applications
• Campus backbone
• High-bandwidth workgroups (multimedia
  application)
• High-bandwidth subworkgroup connection (servers)
• Hardware FDDI concentrator or hub, FDDI/Ethernet
  bridge
• Media fiber optic cable or copper distributed
  data interface (CDDI) for limited distance (100m)

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100VG-AnyLAN

• Ethernet and token ring packets
• Demand priority access (DPA) or demand priority
  protocol round robin polling scheme
• Priority is assigned by application program and
  ports
• Max 4 hubs between two nodes

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100VG-AnyLAN

• Hardware 100VG-AnyLAN hubs arranged in a
  hierarchical form
• Media 4 pair of Category 3, 4, or 5 UTP 1 pair
  of Type 1 STP or single mode and multimode fiber
  optic cable

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Isochronous Ethernet

• Iso-Ethernet in IEEE802.9a (Isochronous Ethernet
  Integrated Services)
• Synchronize all circuits with a single common
  clocking reference
• Guaranteed delivery time for voice and video
• Use ISDN WAN link

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Isochronous Ethernet

• 16.144-Mpbs bandwidth
• P channel for Ethernet traffic
• C channel ( B channel and D channel)
• Service Modes
• 10BaseT
• Mutiservice multimedia
• All-isochronous real time video or voice
  distribution

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Isochronous Ethernet

• Hardware
• hubs Iso-Ethernet attachment units (AU)
• Workstation with Iso-Ethernet NIC integrated
  service terminal equipment (ISTE)

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Wireless

• Transmitter and receiver
• 100 - 300 feet
• Infrared technology (line-of-sight)
• Spread spectrum technology (no ling-of-sight)
• Special application

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Performance Factors

• Protocol (CSMA/CD, token ring)
• Speed of transmission (line)
• Amount of traffic
• Error rate
• Software
• Hardware

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Selection Process

• Long range thinking, planning and forecasting
• Selection team
• Checklist of criteria
• Cost benefit analysis
• Technical alternatives
• Management and Maintenance

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Selection Criteria - I

• Number of user
• Geographic spread
• Applications
• Performance
• Cost
• Security
• Wiring

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Selection Criteria - II

• Installation
• Maintenance
• Vendor support and training
• Future expansion
• Workstations
• Compatibility to existing LANs
• Interface to other networks

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Costs

• Workstations
• Servers
• Printers
• Cabling
• Bridges, routers, brouters, gateways
• Training
• People (consultant, administrator etc.)
• Maintenance
• Space Environment

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Installation

• Choices
• Suppliers or dealers
• In house
• Tasks (project management)
• Install hardware and software
• Test access and capability
• Trouble shoot
• Document
• Train user
• Help center

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Management Maintenance

• Organization LAN administrator
• Management policies and procedures
• Documentation
• Hardware and software control
• Change control
• Back up (hardware and software)
• Security (logical and physical)
• Application (compatibility, integrity,
  efficiency)
• Performance monitoring

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Security

• Password
• Sign off
• Encryption
• Backup
• Downloading
• Viruses protection
• Dial-up access
• Legal software
• Internal and external auditing
• Written policy and procedure

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Assignment

• Review chapter 5
• Read chapter 6