CSE 550 Computer Network Design

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23 Οκτ 2013 (πριν από 3 χρόνια και 10 μήνες)

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CSE 550

Computer Network Design

Dr. Mohammed H. Sqalli

COE, KFUPM


Spring 2008 (Term 072)

CSE
-
550
-
T072

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
-
T072

Lecture Notes
-

1

3

What is a Network?



Management view



Technical view


CSE
-
550
-
T
072

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
-
T
072

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
-
T
072

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
-
T
072

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
-
T
072

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
-
T
072

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
-
T072

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
-
T
072

Lecture Notes
-

1

11

Application Bandwidths

Word Processing

File Transfers

Real
-
Time Imaging

100
s Kbps Few Mbps

Few Mbps
10
s Mbps

10
s Mbps
100
s Mbps

Transaction
Processing

100
Bytes Few Kbps

CSE
-
550
-
T072

Lecture Notes
-

1

12

A Look on Multimedia Networking

Video standard

Bandwidth per
user

WAN 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
-
T
072

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
-
T
072

Lecture Notes
-

1

14

Generations of Networking

CSE
-
550
-
T
072

Lecture Notes
-

1

15

Network Design: Achievable?

Response Time

Cost

Business Growth

Reliability

CSE
-
550
-
T
072

Lecture Notes
-

1

16

Where to begin?

WAN

Campus

Traffic

Patterns

Dial in
Users

Security

WWW
Access

Users

Network

Management

Addressing

CSE
-
550
-
T
072

Lecture Notes
-

1

17

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

CSE
-
550
-
T
072

Lecture Notes
-

1

18

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
-
T
072

Lecture Notes
-

1

19

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
-
T
072

Lecture Notes
-

1

20

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
-
T
072

Lecture Notes
-

1

21

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
-
T
072

Lecture Notes
-

1

22

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

CSE
-
550
-
T
072

Lecture Notes
-

1

23

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

CSE
-
550
-
T
072

Lecture Notes
-

1

24

Network Development Life Cycle

Management

Analysis

Design

Simulation/

Prototyping

Implementation

Monitoring

CSE
-
550
-
T
072

Lecture Notes
-

1

25

Network Design and Implementation Cycle

CSE
-
550
-
T
072

Lecture Notes
-

1

26

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
-
T
072

Lecture Notes
-

1

27

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
-
T
072

Lecture Notes
-

1

28

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
-
T
072

Lecture Notes
-

1

29

Another Perspective



Data collection


Traffic


Costs


Constraints



Design process



Performance analysis



Fine tuning



A painstaking iterative process

CSE
-
550
-
T
072

Lecture Notes
-

1

30

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
-
T
072

Lecture Notes
-

1

31

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
-
T
072

Lecture Notes
-

1

32

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
-
T
072

Lecture Notes
-

1

33

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

CSE
-
550
-
T
072

Lecture Notes
-

1

34

Information Flows between Network
Analysis, Architecture, and Design