1 K. Salah Module 1.0: Introduction Network overview What is ‘network design’? Network Design Lifecycle How it was done Our approach What is expected or unexpected

2 K. Salah What is a Network? Management view Technical view

3 K. Salah Management View 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 Utilities don’t bring money into the organization –Expense item to the Corporation –Cannot justify Network based on “productivity Improvements”

4 K. Salah Management View (cont.) As a network designer, you need to explain to management how the network design, even with the higher expense, can save money or improve the companies business –If users cannot log on to your commerce site, they will try a competitors, 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 You need to understand how the network assists the company in making money and play to that strength when you are developing the network design proposal Try to show a direct correlation between the network design project and the companies 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?

5 K. Salah The Technical View A “Network” really can be thought as of three things and they all need to be considered when working on a network design project –Connections –Communications –Services Connection –Provided by Hardware that ties things together  Wire/Fiber Transport Mechanisms  Routers  Switches/Hubs  Computers Communications –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  SNMP  UDP

6 K. Salah 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 on the problem –No consideration in delay optimisation –No guarantee of service quality

7 K. Salah A Look on Multimedia Networking Video standardBandwidth per userWAN services Digital video interactive1.2 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

8 K. Salah Application characteristics ApplicationsMessage LengthMsg arrival rateDelay needReliability need Interactive terminalsShortLowModerateVery high File transferVery longVery low Very high Hi-resolution graphicsVery longLow to moderateHighLow Packet-sized voiceVery shortVery HighHighLow

9 K. Salah Application Bandwidths Word Processing File Transfers Real-Time Imaging 100s Kbps Few Mbs Few Mbps 10s Mbps 10s Mbps 100s Mbps Transaction Processing 100 Bytes Few Kbps

10 K. Salah Networking issues LAN, MAN and WAN Switching and routing Technologies: Ethernet, FDDI, ATM … Mobile networking Internetworking Applications Service quality Security concerns

11 K. Salah Network Design: Achievable? Response Time Cost Business Growth Reliability

12 K. Salah Where to begin? WAN Campus Traffic Patterns Dial in Users Security WWW Access Users Network Management Addressing

13 K. Salah A Systems Approach Requirement Analysis Flow Analysis Logical Design Physical Design Routing & Addressing

14 K. Salah Requirement Analysis is sometimes called “Conceptual” process Routing & Addressing –Geographical, Functional –Defining Autonomous Systems (AS) –Available IP addresses assigned –NAT usage Flow Analysis can be part of Logical Design Flow Analysis include: – Flow of information from client to server –or- client to client  For delay calculation –Node placement (router, servers, clients) –Network Topology (mesh, ring, bus, backbone) –Multiplexing of Traffic –Prioritized flow or not  Voice  Video Conferencing A Systems Approach (Cont.)

15 K. Salah Another Perspective: Data collection –Traffic –Costs –Constraints Design process Performance analysis Fine tuning A painstaking iterative process

16 K. Salah 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

17 K. Salah Analysis and Design Processes Set and achieve goals –Maximising performance –Minimising cost Optimisation with trade-offs –Recognising trade-offs –No single ‘best’ answer Hierarchies –Provide structure in the network Redundancy –Provides availability & reliability

18 K. Salah Technologies for design Heuristic – by using various algorithms Exact – by working out mathematical solutions based on linear programming etc., minimising certain cost functions Simulation – often used when no exact analytical form exists. Experiments are conducted on simplified models to see the performance of network

19 K. Salah Design and Study of a System

20 K. Salah 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?

21 K. Salah A network design project can be defined on three different levels, each with separate outcomes that must come together in the end –Conceptual - little detail –Logical –Physical - most detail Schema View of Network Design

22 K. Salah User level network requirements –Applications –Speed –Access to Information Management level network requirements –Cost and Budget Limitations –Best Value –Applications to Provide Productivity Improvements –Business Improvement Conceptual

23 K. Salah Enterprise Level Requirements –Centralized / Decentralized Area / Department Level Requirements –High network bandwidth in medical imaging areas –Application Oriented Conceptual Level of Network Design

24 K. Salah  What do the users want? –Services  What do the users need?  What don’t they know they need?  Organize and Prioritize Requirement Conceptual Level of Network Design

25 K. Salah Conceptual Level of Network Design User Requirements  Performance Requirements Timeliness Interactivity Reliability Quality Security Affordability User Numbers User Locations User Growth Capacity Reliability Delay

26 K. Salah Network level requirements based on the conceptual design (the big picture) –what kind of network will meet the conceptual design based on the information gathered –Start to get from idea’s to networking items from a design choice standpoint –Still not at the specific detail level yet Logical Level Network Design

27 K. Salah Network Protocol selection –IP addressing issues –Other protocol addressing issues –How to make all these protocols work together Need for sub-netting (breaking the network into segments) Network Topology to use Simple block diagram type design Logical Level Network Design

28 K. Salah Hardware level requirements –Router performance based on bandwidth requirements –Switches, Repeaters, etc... Equipment location requirements Physical security requirements Physical Level Network Design

29 K. Salah Media selection Bandwidth requirements based on conceptual design You design answers the question- Can a network be built using the logical level requirements Physical Level Network Design

30 K. Salah New network design Re-engineering a network design Network expansion design Types of Network Design

31 K. Salah Actually starting from scratch No legacy networks to accommodate Major driver is the budget, no compatability issues to worry about Getting harder to find these situations New Network Design

32 K. Salah Modifications to an existing network to compensate for original design problems Sometimes required when networks users change existing applications or functionality More of the type of problem seen today Re-engineering a Network Design

33 K. Salah Network designs that expand network capacity Technology upgrades Adding more users or networked equipment Network Expansion Design

34 K. Salah This Whole Thing is Messy

35 K. Salah Ambiguous Requirements –The network will only transport IP –The application requires Novell IPX This Whole Thing is Messy

36 K. Salah Conflicting Requirements –Keep costs down –High performance cost money This Whole Thing is Messy

37 K. Salah Lack of Design Tools Lack of Management Tools Lack of Vendor Interoperability This Whole Thing is Messy

38 K. Salah Lack of Documentation –Existing Network –How things should be done. (I.e. wiring) –Vendor information This Whole Thing is Messy

39 K. Salah 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

40 K. Salah Security –What is enough security? –What is too much security? –security and management can not be dealt 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

41 K. Salah Evolving Network Technologies –Everything is a moving target –Products are put onto the market before standards are approved –Whiz Bang Theory –Everyone is a computer “expert” This Whole Thing is Messy