Module 1 0 Introduction Network overview What is

Module 1. 0: Introduction • • • Network overview What is ‘network design’? Network Design Lifecycle How it was done Our approach What is expected or unexpected K. Salah 1

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

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” K. Salah 3

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? K. Salah 4

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 Ø Wire/Fiber Transport Mechanisms Ø Routers Ø Switches/Hubs Ø Computers • Communications – Provided by Software – A common language for 2 systems to communicate with each other Ø TCP/IP (Internet/Windows NT) Ø IPX / SPX (Novell Netware 4) Ø Apple. Talk Ø Other network OS • Services – The Heart of Networking – Cooperation between 2 or more systems to perform some function - Applications Ø telnet Ø ftp Ø http Ø SNMP Ø UDP K. Salah 5

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 K. Salah 6

A Look on Multimedia Networking Video standard Bandwidth per user WAN services Digital video interactive 1. 2 Mbps DS 1 lines ISDN H 11, Frame Relay, ATM Motion JPEG 10 to 240 Mbps ATM 155 or 622 Mbps MPEG-1 1. 5 Mbps DS 1 lines ISDN H 11, Frame Relay, ATM MPEG-2 4~6 Mbps DS 2, DS 3, ATM at DS 3 rate K. Salah 7

Application characteristics Applications Message Length Msg arrival rate Delay need Reliability need Interactive terminals Short Low Moderate Very high File transfer Very long Very low Very high Hi-resolution graphics Very long Low to moderate High Low Packet-sized voice Very short Very High Low K. Salah 8

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

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

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

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

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

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

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

One More Look Business Planning Network Design Implement Network Operations Define Objectives and Requirements Develop Architecture Create Implementation Plan Develop Operations Policies and Capabilities Create Initial Solution Develop Detailed Design Procure Resources and Facilities Fault Management Define Deployment Strategy Create Build Documentation Stage and Install Configuration Management Review and Approve Review and Verify Design Certify and Hand-off to Operations Change Management Performance Management K. Salah 16

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 K. Salah 17

Design Study Approaches • • • 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 K. Salah 18

Design and Study of a System K. Salah 19

Art or Science? 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 … n n K. Salah 20

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

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

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

Conceptual Level of Network Design ¶ What do the users want? – Services · What do the users need? ¸ What don’t they know they need? ¹ Organize and Prioritize Requirement K. Salah 24

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

Logical Level Network Design • 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 K. Salah 26

Logical Level Network Design • 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 K. Salah 27

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

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

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

New Network Design • • 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 K. Salah 31

Re-engineering a Network Design • 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 K. Salah 32

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

This Whole Thing is Messy K. Salah 34

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

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

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

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

This Whole Thing is Messy • Network Management – More management uses more bandwidth – Every vendor has their own management tools – Vendor tools may conflict with each other K. Salah 39

This Whole Thing is Messy • 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. Firewall 200 Kbs 10 Mb/s Ethernet K. Salah T 1 1. 5 Mb/s 40 10 Mb/s Ethernet

This Whole Thing is Messy • 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” K. Salah 41