cse 550 computer network design
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CSE 550 Computer Network Design. Dr. Mohammed H. Sqalli COE, KFUPM Spring 2008 (Term 072). Introduction. What is a Network? What is “Network Design”? Top-Down Network Design Network Development Life Cycle (NDLC) Network Analysis and Design Methodology Types of Network Design - PowerPoint PPT PresentationTRANSCRIPT
CSE 550Computer Network Design
Dr. Mohammed H. SqalliCOE, KFUPM
Spring 2008 (Term 072)
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Introduction
What is a Network? What is “Network Design”? Top-Down Network Design Network Development Life Cycle (NDLC) Network Analysis and Design Methodology Types of Network Design And Then What?
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What is a Network?
Management view
Technical view
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The Management View (1/3)
A network is a utility Computers and their users are customers of the network
utility The network must accommodate the needs of
customers As computer usage increases so does the requirements of
the network utility Resources will be used to manage the network The Network Utility is NOT free!
Someone must pay the cost of installing and maintaining the network
Manpower is required to support the network utility
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The Management View (2/3)
Utilities don’t bring money into the organization Expense item to the Corporation Cannot justify Network based on “Productivity
Improvements” As a network designer, you need to explain to
management how the network design, even with the high expense, can save money or improve the company’s business If users cannot log on to your commerce site, they will try
your competitor, and you have lost sales If you cannot get the information your customers are
asking about due to a network that is down, they may go to your competitor
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The Management View (3/3)
You need to understand how the network assists the company in making money and play on that strength when you are developing the network design proposal
Try to show a direct correlation between the network design project and the company’s business
“Because you want a faster network” is not good enough, the question that management sends back is WHY DO I NEED A FASTER ONE?
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The Technical View (1/2)
A “Network” really can be thought of as three parts and they all need to be considered when working on a network design project:
Connections Communications/Protocols Services
Connections Provided by Hardware that ties things together
Wire/Fiber/Wireless Transport Mechanisms Routers Switches/Hubs Computers
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The Technical View (2/2)
Communications/Protocols Provided by Software A common language for 2 systems to communicate with each other
TCP/IP (Internet/Windows NT) IPX / SPX (Novell Netware 4) AppleTalk Other Network OS
Services The Heart of Networking Cooperation between 2 or more systems to perform some function -
Applications telnet FTP HTTP SMTP
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Traditional Network Design
Based on a set of general rules “80/20” “Bridge when you can, route when you must” Can’t deal with scalability & complexity
Focused on capacity planning Throw more bandwidth at the problem No consideration to delay optimization No guarantee of service quality Less importance given to network RMA (Reliability,
Maintainability, and Availability) compared to throughput
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Application Characteristics
Applications Message Length
Message arrival rate
Delay need Reliability need
Interactive terminals
Short Low Moderate Very high
File transfer Very long Very low Very low Very high
Hi-resolution graphics
Very long Low to moderate
High Low
Packetized voice
Very short Very high High Low
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Application Bandwidths
Word Processing
File Transfers
Real-Time Imaging
100s Kbps Few Mbps
Few Mbps 10s Mbps
10s Mbps 100s Mbps
Transaction Processing 100 Bytes Few Kbps
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A Look on Multimedia NetworkingVideo standard Bandwidth per
userWAN services
Digital video interactive
1.2 Mbps DS1 lines ISDN H11, Frame Relay, ATM
Motion JPEG 10 to 240 Mbps ATM 155 or 622 Mbps
MPEG-1 1.5 Mbps DS1 lines ISDN H11, Frame Relay, ATM
MPEG-2 4~6 Mbps DS2, DS3, ATM at DS3 rate
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Some Networking Issues
LAN, MAN and WAN Switching and routing Technologies: Ethernet, FDDI, ATM … Wireless/Mobile networking Internetworking Applications Service quality Security concerns
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Generations of Networking
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Network Design: Achievable?
Response Time Cost
Business GrowthReliability
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Where to begin?
WAN
CampusCampus
TrafficTrafficPatternsPatterns
Dial in Dial in UsersUsers
SecuritySecurity
WWW WWW AccessAccess
UsersUsers
NetworkNetworkManagementManagement
AddressingAddressing
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Traditional Network Design Methodology
Many network design tools and methodologies in use today resemble the “connect-the-dots” game
These tools let you place internetworking devices on a palette and connect them with LAN or WAN media
Problem with this methodology: It skips the steps of analyzing a customer's
requirements, and selecting devices and media based on those requirements
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Top-Down Network Design Methodology (1/2)
Good network design Recognizes that a customer’s requirements embody
many business and technical goals May specify a required level of network performance,
i.e., service level Includes difficult network design choices and tradeoffs
that must be made when designing the logical network before any physical devices or media are selected
When a customer expects a quick response to a network design request A bottom-up (connect-the-dots) network design
methodology can be used, if the customer’s applications and goals are well known
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Top-Down Network Design Methodology (2/2)
Network designers often think they understand a customer’s applications and requirements.
However, after the network installation, they may discover that: They did not capture the customer's most important
needs Unexpected scalability and performance problems
appear as the number of network users increases
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Top-Down Network Design Process (1/2)
Begins at the upper layers of the OSI reference model before moving to the lower layers Focuses on applications, sessions, and data transport
before the selection of routers, switches, and media that operate at the lower layers
Explores divisional structures to find the people: For whom the network will provide services, and From whom to get valuable information to make the
design succeed
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Top-Down Network Design Process (2/2)
It is an iterative process: It is important to first get an overall view of a
customer's requirements More detail can be gathered later on protocol behavior,
scalability requirements, technology preferences, etc. Recognizes that the logical model and the physical
design may change as more information is gathered A top-down approach lets a network designer get
“the big picture” first and then spiral downward into detailed technical requirements and specifications
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Structured Network Design Process- A Systems Approach (1/2) -
The system is designed in a top-down sequence Several techniques and models can be used to
characterize the existing system, new user requirements, and a structure for the future system
A focus is placed on understanding: Data flow, data types, and processes that access or
change the data The location and needs of user communities that
access or change data and processes
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Structured Network Design Process- A Systems Approach (2/2) - A logical model is developed before the physical
model The logical model represents the basic building blocks,
divided by function, and the structure of the system The physical model represents devices and specific
technologies and implementations
For large network design projects, modularity is essential The design should be split functionally to make the
project more manageable
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Network Development Life Cycle
Management
Analysis
Design
Simulation/Prototyping
Implementation
Monitoring
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Network Design and Implementation Cycle
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Network Design and Implementation Cycle (1/3)
Analyze requirements: Interviews with users and technical personnel Understand business and technical goals for a
new or enhanced system Characterize the existing network: logical and
physical topology, and network performance Analyze current and future network traffic,
including traffic flow and load, protocol behavior, and QoS requirements
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Network Design and Implementation Cycle (2/3)
Develop the logical design: Deals with a logical topology for the new or
enhanced network Network layer addressing and naming Switching and routing protocols Security planning Network management design Initial investigation into which service
providers can meet WAN and remote access requirements
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Network Design and Implementation Cycle (3/3)
Develop the physical design: Specific technologies and products to realize the
logical design are selected The investigation into service providers must be
completed during this phase
Test, optimize, and document the design: Write and implement a test plan Build a prototype or pilot Optimize the network design Document your work with a network design proposal
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Another Perspective
Data collection Traffic Costs Constraints
Design process Performance analysis Fine tuning A painstaking iterative process
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PDIOO Network Life Cycle (1/3)(Cisco)
Plan: Network requirements are identified in this phase Analysis of areas where the network will be installed Identification of users who will require network services
Design: Accomplish the logical and physical design, according
to requirements gathered during the Plan phase
Implement: Network is built according to the Design specifications Implementation also serves to verify the design
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PDIOO Network Life Cycle (2/3)(Cisco)
Operate: Operation is the final test of the effectiveness of the design The network is monitored during this phase for performance
problems and any faults, to provide input into the Optimize phase
Optimize: Based on proactive network management which identifies
and resolves problems before network disruptions arise The optimize phase may lead to a network redesign
if too many problems arise due to design errors, or as network performance degrades over time as actual
use and capabilities diverge Redesign may also be required when requirements change
significantly
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PDIOO Network Life Cycle (3/3)(Cisco)
Retire: When the network, or a part of the network, is out-of-date, it
may be taken out of production Although Retire is not incorporated into the name of the life
cycle (PDIOO), it is nonetheless an important phase
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One More Look
Define Objectivesand Requirements
Create InitialSolution
Define DeploymentStrategy
DevelopArchitecture
Create BuildDocumentation
Develop DetailedDesign
Review and VerifyDesign
CreateImplementation Plan
Procure Resourcesand Facilities
Stage and Install
Certify and Hand-offto Operations
Develop OperationsPolicies andCapabilities
ConfigurationManagement
FaultManagement
ChangeManagement
PerformanceManagement
Review andApprove
BusinessBusinessPlanningPlanning
OperationsOperationsImplementImplementNetworkNetwork
Network Network DesignDesign
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Information Flows between Network Analysis, Architecture, and Design