Download Chapter 11 Network Fundamentals

Chapter 11
Network Fundamentals
Agenda
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Definition
Classification
Information Routing
Connection
Telecommunication software
Architecture
Definition
• Network
• Backbone network
Classification
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Topology
Ownership
Geography
Transmission
Network Topology
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Star
Hierarchical
Mesh
Bus
Ring
Hybrid
Star Network
• Circuits
– Point-to-point, multipoint, or combination
• Pros
– Expand
– Implement
– No limit to no. and length of arms
• Cons
– Single point of failure
– Overload of mater during peak traffic
Hierarchical Network
• Tree structure with a root
• pro
– No single point of failure
– Divisional communications and processing
Mesh Network
• Web structure
• Usage
– Public telephone system
• Pro
– Alternative communication route
– Virtually fail-safe
• Con
– Line cost
Bus Network
• Usage
– High speed, short distance between nodes
– Local area network
• Pros
– Independent between nodes
– High reliability
• Cons
– Limited number of attached device
– Hard to locate the problems
Ring Network
• Usage
– Nodes are relatively close together
• Pros
– Less attenuation
– Error control
– Network management
• Cons
– Failing of a node
• Two opposite direction channels
Hybrid Networks
• Usage
– Connecting different networks
• Pro
– Communication between different networks
• Con
– Conversion device and costs
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
• Public network
• Functions
– Code translation
– Speed conversion
– Store message and delivery
• Examples
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Telex
SWIFT
SITA (airline)
IVAN (insurance)
Networks by Geography
• Wide area network (WAN)
• Metropolitan area network (MAN)
• Local area network (LAN)
Wide Area Networks
• Public Switched Telephone Network
(PSTN)
• Provided by carriers
• Inexpensive
• High quality service for infrequent users
Metropolitan Area Networks
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IEEE 802.6
Distance up to 30 miles
High bandwidth for data, voice, and video
T1, T3, or fiber optic cable
Private own or dark fiber supplied by MAN
provider
Network Transmission Types
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Circuit Switching
Packet data networks (PDNs)
Frame relay
Asynchronous transfer mode: ATM (Cell
relay)
Circuit Switching
• Temporarily Dedicated communications
line between two stations for transmission
• Efficient for constant voice and video
transmission
• Inefficient for non-constant data
transmission
Packet Data networks (PDNs) - I
• Packet
– Less than 1,000 bytes
– PAD (packet assembly/disassembly)
– Address and control fields for error checking
• Connection types
– Switched virtual circuit: dial-in (switched)
– Permanent virtual (leased) circuit: heavy &
frequent traffic
– Datagram: short message, no error checking
Packet Data networks (PDNs) - II
• Standard
– ITU-T’s X.25
• Between terminal and PDN on public network
– ITU-T’s X.75
• Interface between two PDNs
• Examples
– USA: APARANET, Telenet, Tymnet, General
Electric Information Services (GEIS)
Packet Data networks (PDNs) - III
• Characteristics
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Reliable service
Nationwide service
Lower error rates
Variety of transmission speeds
Cost-effectiveness
Frame Relay
• Acknowledge only by final node
• Benefits
– Variable-length frames (1- 64,000 bytes)
– Reduce overhead
– More efficient transmission
• Problems
– Circuit congestion
– Committed information rate (CIR) & port speed
for service guarantee & discarding frames
ATM (Cell-Relay)
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Asynchronous transfer mode (ATM)
Cells : fixed length packets of 53 bytes
45Mbps (T3) or higher speeds
Pros
– High throughput, low delay, transparency,
flexibility, and high capacity
• Con
– Expensive
ATM Services
• Realtime service
– Constant bit rate (CBR) for telephone and
videoconference
– Realtime variable bit rate (rt-VBR) for compressed
video
• Non-realtime service
– Non-realtime variable bit rate (nrt-VBR) for airline
reservation or financial transaction
– Available bit rate (ABR) for LAN-to-LAN
– Unspecified bit rate (UBR) for TCP-based traffic
Routing Message
• Connection-oriented routing & connection
less routing
• Broadcast routing
• Centralized routing
• Distributed routing
• Static and dynamic routing
Broadcasting Routing
• CSMA/CD
• Pros and cons
– Simplest
– For small network
– Not for moderate to heavy traffic
Centralized Routing
• Star or hierarchical networks
– IBM’s SNA networks
• Using static routing table in one central
computer
• Pros and cons
– Simple
– Potential performance bottleneck
– Single point of failure
Distributed Routing
• Routing tables on several nodes
• Pros and cons
– No single point of failure
– Routing table update problem
– Complicated to implement
Static and Dynamic Routing
• Static routing
– Predetermined route
– Simple but inflexible
• Dynamic routing
– Use routing algorithms to evaluate traffic
volumes, error rates, and other conditions for
the best path
– Flexible but high overhead and complicated to
implement
Interconnecting Networks
• Transmission control protocol/ internet
protocol (TCP/IP)
• Internet
• Intranet & extranet
Transmission Control Protocol
• OSI transport layer
• Connection oriented
• Functions
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Assemble and reassemble message packets
Reliable & error free message delivery
Urgency or priority
Security (encryption)
Internet Protocol
• OSI network layer
• Routing & addressing messages to other
networks
• Connectionless operation
• IPv6
– 128 bits for addressing
– Quick and efficient
TCP/IP Application protocols
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File Transfer Protocol (FTP)
Tenet
Simple Mail Transfer Protocol (SMTP)
Multipurpose Internet Mail Extensions
(MIME)
• Remote Procedure Call (RPC)
• Simple Network Management Protocol
(SNMP)
Internet
• Usages
– Electronic mail, remote log in to various computers,
discussion groups, information search and retrieval
• Electronic mail (e-mail)
– Edu, com, org, gov, mil, net
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Web servers & web browsers
Hypertext Markup Language (HTML)
Uniform Resource Locator (URL)
Home page
Internet service provider (ISP)
Intranets & Extranets
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Intranets
Extranets
Benefits: fast information transmission
Problems: security & privacy
Connect Network to Computer
• Methods
– Direct connection between circuit and computer
• Small network
• Low cost
• Cycle stealing
– Network interface card
– Use a front-end processor: telecommunication
control unit or transmission control unit
• Large host computer
• Better utilize computer resources
Front-end Processors (FEPs)
• Types
– Hardware (interface or port): speed
– Software ( network control program NCP):
flexible
FEPs - Functions
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Circuit control
Assembly messages
Message queuing or storing
Error control
Administration functions
Functions of Telecommunication Software
in Host Computer
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Security
Buffer management
Routing a message to a program
Queuing messages
Scheduling application program
Providing continuity between part of a transaction
Message formatting
Checkpoint/restart
Preventing messages from lost or duplicated
Software for Network Management
• Control and monitor the network status
– Start/stop network, terminal, and line
– Performance
• Log network operation
• Display network data
Manufacturers’ Architectures
• IBM’s System Network Architecture (SNA)
• Digital Equipment Corporation’s Digital
Network Architecture (DNA)
IBM’s SNA Concepts
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Physical units
Logical units
Sessions
Network addressing units (NAUs)
Data link protocols
SNA software
– Network Control program (NCP)
– Virtual Telecommunications Access Method
SNA Physical Units
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Terminals (1)
Cluster controllers (2)
Front-end processors (4)
Host computers (5)
SNA Logical Units
• People
• Application programs
SNA Sessions
• Types
– Terminal-to-terminal
– Terminal-to-program
– Program-to-program
• Modes
– Interactive
– Batch
– Multiple simultaneous
SNA Network Addressable Units
• Physical units
• Logical units
• Address: 24 bits
SNA Data Link Protocols
• Synchronous Data Link control (SDLC)
• Binary Synchronous Communications
(BISYNC or BSC)
• X.25
System Network Architecture
• Physical control
– Physical and electrical connections
– Transmission codes
– Voltages
• Data link control
– Format
– Reliability
• Path control
– Routing information
• Transmission control
– Security & compression
• Data flow control
– Flow control
• Presentation services
– Format
• Transaction services
– Coordinating application software
Digital’s DNA -I
• Protocols
– Digital Data Communication Message Protocol
(DDCMP)
– X.25
– Ethernet
• DECNET Layers
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Application
Network service
Transport
Data link control
Physical link control
Points to Remember
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Definition
Classification
Information Routing
Connection
Telecommunication software
Architecture
Discussion
• Does CSUS need a backbone network?
• What type of backbone do you think that CSUS
needs (give your justifications)?
• What type of network does CSUS needs in terms
of topology, ownership, geography and
transmission technology?
• What type of network does a grocery chain store
needs in terms of topology, ownership, geography
and transmission technology?