1. CSE 550 Computer Network Design Dr. Mohammed H. Sqalli COE, KFUPM Spring 2008 (Term 072)

2. CSE-550-T072 Lecture Notes - 12 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?

3. CSE-550-T072 Lecture Notes - 13 What is a Network? Management view Technical view

4. CSE-550-T072 Lecture Notes - 14 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

5. CSE-550-T072 Lecture Notes - 15 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

6. CSE-550-T072 Lecture Notes - 16 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?

7. CSE-550-T072 Lecture Notes - 17 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

8. CSE-550-T072 Lecture Notes - 18 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

9. CSE-550-T072 Lecture Notes - 19 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

10. CSE-550-T072 Lecture Notes - 110 Application Characteristics ApplicationsMessage Length Message arrival rate Delay needReliability need Interactive terminals ShortLowModerateVery high File transferVery longVery low Very high Hi-resolution graphics Very longLow to moderate HighLow Packetized voice Very shortVery highHighLow

11. CSE-550-T072 Lecture Notes - 111 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

12. CSE-550-T072 Lecture Notes - 112 A Look on Multimedia Networking Video standardBandwidth per user WAN services Digital video interactive 1.2 MbpsDS1 lines ISDN H11, Frame Relay, ATM Motion JPEG10 to 240 MbpsATM 155 or 622 Mbps MPEG-11.5 MbpsDS1 lines ISDN H11, Frame Relay, ATM MPEG-24~6 MbpsDS2, DS3, ATM at DS3 rate

13. CSE-550-T072 Lecture Notes - 113 Some Networking Issues LAN, MAN and WAN Switching and routing Technologies: Ethernet, FDDI, ATM … Wireless/Mobile networking Internetworking Applications Service quality Security concerns

14. CSE-550-T072 Lecture Notes - 114 Generations of Networking

15. CSE-550-T072 Lecture Notes - 115 Network Design: Achievable? Response Time Cost Business Growth Reliability

16. CSE-550-T072 Lecture Notes - 116 Where to begin? WAN Campus Traffic Patterns Dial in Users Security WWW Access Users Network Management Addressing

17. CSE-550-T072 Lecture Notes - 117 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

18. CSE-550-T072 Lecture Notes - 118 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

19. CSE-550-T072 Lecture Notes - 119 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

20. CSE-550-T072 Lecture Notes - 120 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

21. CSE-550-T072 Lecture Notes - 121 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

22. CSE-550-T072 Lecture Notes - 122 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

23. CSE-550-T072 Lecture Notes - 123 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

24. CSE-550-T072 Lecture Notes - 124 Network Development Life Cycle Management Analysis Design Simulation/ Prototyping Implementation Monitoring

25. CSE-550-T072 Lecture Notes - 125 Network Design and Implementation Cycle

26. CSE-550-T072 Lecture Notes - 126 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

27. CSE-550-T072 Lecture Notes - 127 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

28. CSE-550-T072 Lecture Notes - 128 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

29. CSE-550-T072 Lecture Notes - 129 Another Perspective Data collection Traffic Costs Constraints Design process Performance analysis Fine tuning A painstaking iterative process

30. CSE-550-T072 Lecture Notes - 130 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

31. CSE-550-T072 Lecture Notes - 131 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

32. CSE-550-T072 Lecture Notes - 132 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

33. CSE-550-T072 Lecture Notes - 133 One More Look Define Objectives and Requirements Create Initial Solution Define Deployment Strategy Develop Architecture Create Build Documentation Develop Detailed Design Review and Verify Design Create Implementation Plan Procure Resources and Facilities Stage and Install Certify and Hand-off to Operations Develop Operations Policies and Capabilities Configuration Management Fault Management Change Management Performance Management Review and Approve Business Planning Operations Implement Network Network Design

34. CSE-550-T072 Lecture Notes - 134 Information Flows between Network Analysis, Architecture, and Design

35. CSE-550-T072 Lecture Notes - 135 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 -

36. CSE-550-T072 Lecture Notes - 136 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

37. CSE-550-T072 Lecture Notes - 137 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

38. CSE-550-T072 Lecture Notes - 138 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) -

39. CSE-550-T072 Lecture Notes - 139 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

40. CSE-550-T072 Lecture Notes - 140 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

41. CSE-550-T072 Lecture Notes - 141 ¶ What do the users want? Services · What do the users need? ¸ What don’t they know but they need? ¹ Organize and Prioritize Requirement Customer’s Requirements - Users’ Needs -

42. CSE-550-T072 Lecture Notes - 142 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

43. CSE-550-T072 Lecture Notes - 143 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

44. CSE-550-T072 Lecture Notes - 144 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

45. CSE-550-T072 Lecture Notes - 145 Design and Study of a System

46. CSE-550-T072 Lecture Notes - 146 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?

47. CSE-550-T072 Lecture Notes - 147 New network design Re-engineering a network design Network expansion design Types of Network Design

48. CSE-550-T072 Lecture Notes - 148 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

49. CSE-550-T072 Lecture Notes - 149 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

50. CSE-550-T072 Lecture Notes - 150 Network designs that expand network capacity Technology upgrades Adding more users or networked equipment Network Expansion Design

51. This Whole Thing is Messy

52. CSE-550-T072 Lecture Notes - 152 Ambiguous Requirements The network will only transport IP The application requires Novell IPX This Whole Thing is Messy

53. CSE-550-T072 Lecture Notes - 153 Conflicting Requirements Keep costs down High performance cost money This Whole Thing is Messy

54. CSE-550-T072 Lecture Notes - 154 Lack of Design Tools Lack of Management Tools Lack of Vendor Interoperability This Whole Thing is Messy

55. CSE-550-T072 Lecture Notes - 155 Lack of Documentation Existing network How things should be done (e.g., wiring) Vendor information This Whole Thing is Messy

56. CSE-550-T072 Lecture Notes - 156 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

57. CSE-550-T072 Lecture Notes - 157 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 Ethernet T1 1.5Mb/s Firewall 200Kbs

58. CSE-550-T072 Lecture Notes - 158 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

59. CSE-550-T072 Lecture Notes - 159 OAM&P Operations, Administration, Maintenance, Provisioning

60. CSE-550-T072 Lecture Notes - 160 Functional Flow Chart

61. CSE-550-T072 Lecture Notes - 161 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, 2nd edition, 2004 J. McCabe, “Network Analysis, Architecture, and Design” Morgan Kaufmann Publishers, Inc., 2nd edition, 2003 J. E. Goldman, “Applied Data Communications - A Business-Oriented Approach”, 1998