chapter 5
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TRANSCRIPT
Chapter 5Local Area Network
Concepts and Architecture
• Network Fundamentals
• Local Area Network (LAN)
• Open Systems Interconnection (OSI)
• LAN Architectures
Network Fundamentals
• Definitions
• Classifications
• Network topology
• Network types
• Local Area Network
Definition
• Network
• Backbond network
Classification
• Topology
• Ownership
• Geography
• Transmission
Network Topology
• Star
• Hierarchical
• Mesh
• Bus
• Ring
• Hybrid
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
Hierarchical Network
• Usage– Distributed processing
• Tree structure with a root
• pro– No single point of failure
Mesh Network
• Web structure
• Usage– Public telephone system
• Pro– Alternative communication route
• Con– Line cost
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
Ring Network
• Usage– Manufacturing
• Pros– Less attenuation– Error control– Network management
• Cons– Failing of a node
Hybrid Networks
• Usage– Connecting different networks
• Pro– Communication between networks
• Con– Conversion device and costs– Compatibility
Network Ownership
• Private networks
• Public networks
• Valued added networks
Private networks
• Full control
• Special needs
• Expense
Public networks
• Controlled by carriers
• Regulated by government
• Inexpensive
Valued Added Networks
• Functions– Code translation– Speed conversion– Store message and delivery
• Examples– Telex– SWIFT– SITA (airline)– IVAN (insurance)
Networks by Geography
• Wide area network (WAN)
• Metropolitan area network (MAN): 30 miles
• Local area network (LAN): 5 miles
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
Business Needs
• Corporate asset for competitive edge
• Data accessibility (information distribution)
• Less expenses
• Better service - response time and reliability
• Higher productivity
• Control or secure
LAN Analysis & Design
• Meet business objectives (strategic planning)
• Prevent technological obsolescence
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
Open System Interconnection Model
• International Standards Organization
• Interconnection of dissimilar network
• Seven Layers– Application– Presentation– Session – Transport– Network– Data Link– Physical
Application Layer
• Utilities support end-user application program
• Determine data to be send at originating end
• Process data at receiving end
Presentation Layer
• Change data format
• Compression/expansion
• Encryption/decryption
Session Layer
• Communication rules of machines or application programs
• Accounting functions
Transport Layer
• Identify receiving address
• Flow control: rate of transmission
• Recovery: calculate and check checksum of entire message
Network Layer
• Route message
• Dissemble and assemble data (packets)
• Accounting functions
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
Physical Layer
• Electrical, mechanical, procedural specifications for data transmission
• Hardware specification by RS-232-C
Other Concepts
• Protocol
• Encapsulation/ de-encapsulation
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
LAN Architecture Model
• Network architecture includes– Access methodology– Logical topology– Physical topology
• Network configuration includes– Network architecture– Media choice
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
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
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
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)
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
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)
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
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)
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
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
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
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
Isochronous Ethernet
• Hardware:– hubs: Iso-Ethernet attachment units (AU) – Workstation with Iso-Ethernet NIC: integrated
service terminal equipment (ISTE)
Wireless
• Transmitter and receiver
• 100 - 300 feet
• Infrared technology (line-of-sight)
• Spread spectrum technology (no ling-of-sight)
• Special application
Performance Factors
• Protocol (CSMA/CD, token ring)
• Speed of transmission (line)
• Amount of traffic
• Error rate
• Software
• Hardware
Selection Process
• Long range thinking, planning and forecasting
• Selection team
• Checklist of criteria
• Cost & benefit analysis
• Technical alternatives
• Management and Maintenance
Selection Criteria - I
• Number of user
• Geographic spread
• Applications
• Performance
• Cost
• Security
• Wiring
Selection Criteria - II
• Installation
• Maintenance
• Vendor support and training
• Future expansion
• Workstations
• Compatibility to existing LANs
• Interface to other networks
Costs• Workstations
• Servers
• Printers
• Cabling
• Bridges, routers, brouters, gateways
• Training
• People (consultant, administrator etc.)
• Maintenance
• Space & Environment
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
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
Security
• Password• Sign off• Encryption• Backup• Downloading• Viruses protection• Dial-up access• Legal software• Internal and external auditing• Written policy and procedure
Assignment
• Review chapter 5
• Read chapter 6