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CSE-550-T112 Lecture Notes - 1 2
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?
CSE-550-T112 Lecture Notes - 1 4
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
CSE-550-T112 Lecture Notes - 1 5
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
CSE-550-T112 Lecture Notes - 1 6
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?
CSE-550-T112 Lecture Notes - 1 7
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
CSE-550-T112 Lecture Notes - 1 8
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
CSE-550-T112 Lecture Notes - 1 9
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
CSE-550-T112 Lecture Notes - 1 10
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
CSE-550-T112 Lecture Notes - 1 11
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
CSE-550-T112 Lecture Notes - 1 12
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
CSE-550-T112 Lecture Notes - 1 13
Some Networking Issues
LAN, MAN and WAN Switching and routing Technologies: Ethernet, FDDI, ATM … Wireless/Mobile networking Internetworking Applications Service quality Security concerns
CSE-550-T112 Lecture Notes - 1 14
Network Design: Achievable?
Response Time Cost
Business GrowthReliability
CSE-550-T112 Lecture Notes - 1 15
Where to begin?
WAN
CampusCampus
TrafficTrafficPatternsPatterns
Dial in Dial in UsersUsers
SecuritySecurity
WWW WWW AccessAccess
UsersUsers
NetworkNetworkManagementManagement
AddressingAddressing
CSE-550-T112 Lecture Notes - 1 16
Traditional Network Design Methodology
Many network design tools and methodologies that have been used 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
CSE-550-T112 Lecture Notes - 1 17
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
CSE-550-T112 Lecture Notes - 1 18
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
CSE-550-T112 Lecture Notes - 1 19
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
CSE-550-T112 Lecture Notes - 1 20
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
CSE-550-T112 Lecture Notes - 1 21
Network Development Life Cycle
Management
Analysis
Design
Simulation/Prototyping
Implementation
Monitoring
CSE-550-T112 Lecture Notes - 1 23
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
CSE-550-T112 Lecture Notes - 1 24
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
CSE-550-T112 Lecture Notes - 1 25
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
CSE-550-T112 Lecture Notes - 1 26
Another Perspective
Data collection Traffic Costs Constraints
Design process Performance analysis Fine tuning A painstaking iterative process
CSE-550-T112 Lecture Notes - 1 27
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
CSE-550-T112 Lecture Notes - 1 28
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
CSE-550-T112 Lecture Notes - 1 29
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
CSE-550-T112 Lecture Notes - 1 30
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
CSE-550-T112 Lecture Notes - 1 31
Information Flows between Network Analysis, Architecture, and Design
CSE-550-T112 Lecture Notes - 1 32
Requirements (business, application, and data) definition is required prior to network design activities
Expected compliance with requirements in a Request For Proposal (RFP) by both in-house personnel and outside consultants
Activities from various stages often take place simultaneously and backtrack to previous activities is sometimes needed
This methodology is an overall guideline to the network development process rather than “cookbook” instructions
Network Analysis and Design Methodology- Overall Characteristics -
CSE-550-T112 Lecture Notes - 1 33
Network Analysis and Design Methodology- Critical Success Factors of the NDLC (1/3) -
Identification of all potential customers and constituencies All groups must be consulted
Political awareness: Corporate culture: hierarchical, distributed, or open Backroom politics can play a role in systems design Find ways to ensure objectivity of the analysis and design
process (e.g., measurable goals) Buy-in:
Reach consensus on the acceptability of results of each stage Approved results of one stage become the foundation or
starting point for the next stage Makes the final presentation smoother
CSE-550-T112 Lecture Notes - 1 34
Network Analysis and Design Methodology- Critical Success Factors of the NDLC (2/3) -
Communication: With all groups Write memos, communicate with key people in person,
etc. Detailed project documentation:
Prepare agendas Take meeting minutes Action items Use a project binder for all the above
CSE-550-T112 Lecture Notes - 1 35
Process/Product awareness: Stay focused: what is the process/product at each
stage? Keep meeting on track: no off-subject discussions
Be honest with yourself: Be your own harshest critic (no one else knows the
potential weaknesses or areas for improvement in your proposal better than you)
Use peer reviews Not all weaknesses can be corrected (e.g., financial or
time constraints)
Network Analysis and Design Methodology- Critical Success Factors of the NDLC (3/3) -
CSE-550-T112 Lecture Notes - 1 36
Network Analysis and Design Methodology - Overall Guidelines -
Start with a clearly defined problem: Identify affected parties and representatives Held brainstorming sessions to define problems and
requirements of a solution Understand strategic business objectives defined by
senior management Collect baseline data from customer groups about
the current status of the system and network This is used to measure eventual impact of the
installed network Perform a feasibility study: problem definition and
associated alternative recommendations for further study
CSE-550-T112 Lecture Notes - 1 37
Customer’s Requirements- Understanding the Customer -
A good network design must recognize the customer’s requirements - need to make sure your design meets THEIR needs and not just YOURS!
The “Customer” may be your own firm, the “who” you are designing the network for
Need an overview of a customer’s requirements The best designed network will fail miserably without
the support of people
CSE-550-T112 Lecture Notes - 1 38
What do the users want? Services
What do the users need? What don’t they know but they need? Organize and Prioritize Requirement
Customer’s Requirements- Users’ Needs -
CSE-550-T112 Lecture Notes - 1 39
Customer’s Requirements- How they are used -
User Requirements Performance Requirements
• Timeliness• Interactivity• Reliability• Quality• Security• Affordability• User Numbers• User Locations• User Growth
Capacity
Reliability
Delay
CSE-550-T112 Lecture Notes - 1 40
Analysis and Design Processes
Set and achieve goals Maximizing performance Minimizing cost
Optimization with trade-offs Recognizing trade-offs No single ‘best’ answer
Hierarchies Provide structure in the network
Redundancy Provides availability & reliability
CSE-550-T112 Lecture Notes - 1 41
Approaches Used for Design
Heuristic – by using various algorithms Exact – by working out mathematical
solutions based on linear programming, etc., minimizing certain cost functions
Simulation – often used when no exact analytical form exists. Experiments are conducted on simplified models to see the performance of a network
CSE-550-T112 Lecture Notes - 1 43
The Art of Network Design• Technology choices
• Relations to business goals
The Science of Network Design Understanding of network technologies
Analysis of capacity, redundancy, delay …
Art or Science?
CSE-550-T112 Lecture Notes - 1 44
New network design
Re-engineering a network design
Network expansion design
Types of Network Design
CSE-550-T112 Lecture Notes - 1 45
Actually starting from scratch
No legacy networks to accommodate
Major driver is the budget, no compatibility issues to worry about
Getting harder to find these situations
New Network Design
CSE-550-T112 Lecture Notes - 1 46
Modifications to an existing network to compensate for original design problems
Sometimes required when network users change existing applications or functionality
More of the type of problems seen today
Re-engineering a Network Design
CSE-550-T112 Lecture Notes - 1 47
Network designs that expand network capacity
Technology upgrades
Adding more users or networked equipment
Network Expansion Design
CSE-550-T112 Lecture Notes - 1 49
Ambiguous Requirements
The network will only transport IP
The application requires Novell IPX
This Whole Thing is Messy
CSE-550-T112 Lecture Notes - 1 50
Conflicting Requirements
Keep costs down
High performance costs money
This Whole Thing is Messy
CSE-550-T112 Lecture Notes - 1 51
Lack of Design Tools
Lack of Management Tools
Lack of Vendor Interoperability
This Whole Thing is Messy
CSE-550-T112 Lecture Notes - 1 52
Lack of Documentation
Existing network
How things should be done (e.g., wiring)
Vendor information
This Whole Thing is Messy
CSE-550-T112 Lecture Notes - 1 53
Network Management
More management uses more bandwidth
Every vendor has their own management tools
Vendor tools may conflict with each other
This Whole Thing is Messy
CSE-550-T112 Lecture Notes - 1 54
Security What is enough security? What is too much security?
Security and management can not be dealt with as ‘afterthoughts’. It is not an add-on feature, it has to be integrated within.
This Whole Thing is Messy
10Mb/s
Ethernet
10Mb/s
EthernetT1 1.5Mb/s
Firewall 200Kbs
CSE-550-T112 Lecture Notes - 1 55
Evolving Network Technologies Everything is a moving target Products are put onto the market before
standards are approved Everyone is a computer “expert”
This Whole Thing is Messy
CSE-550-T112 Lecture Notes - 1 56
OAM&POperations, Administration, Maintenance, Provisioning
NetworkManagement
NetworkProvisioning
Network Operations
NetworkMaintenance
Planning
Design
Fault Management
Trouble Ticket
Administration
Network Installation
Network Repairs
Facilities Installation
& Maintenance
Routine Network
Tests
Fault Management / Service Restoration
Configuration Management
Performance Management / Traffic Management
Security Management
Accounting Management
Reports Management
Inventory Management
Data Gathering & Analyses
Figure 1.21 Network Management Functional Groupings
CSE-550-T112 Lecture Notes - 1 57
Functional Flow Chart
Engineering Group
- Network Planning &Design
Operations GroupNOC
- Network Operations
I & M Group
-Network Installation &Maintenance
Fault TT
Configuration Data
TT RestorationPerformance & Traffic Data
Installation
Figure 1.22. Network Management Functional Flow Chart
NewTechnology
Network
Users
ManagementDecision
CSE-550-T112 Lecture Notes - 1 58
References
Dr. Khalid Salah (ICS, KFUPM), CSE 550 Lecture Slides, Term 032
Dr. Marwan Abu-Amara (COE, KFUPM), CSE 550 Lecture Slides, Term 052
P. Oppenheimer, “Top-Down Network Design,” Cisco Press, 3rd edition, 2010
J. McCabe, “Network Analysis, Architecture, and Design” Morgan Kaufmann Publishers, Inc., 3rd edition, 2007
J. E. Goldman, “Applied Data Communications - A Business-Oriented Approach”, 1998
Mani Subramanian, “Network Management – Principles and Practice” by, Pearson, Second Edition, 2010.
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