chapter 9 designing a network 9.1 network models network modelsnetwork models 9.2network performance...
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Chapter 9 Designing a Chapter 9 Designing a NetworkNetwork
9.1 9.1 Network ModelsNetwork Models
9.29.2 Network PerformanceNetwork Performance
9.39.3 Network PlanNetwork Plan
Chapter 9 Designing a Network
9.1 Network Models
There are two fundamental models of network Peer-to-peer client/server
Chapter 9 Designing a Network
9.1.1 Peer-to-peer Model
Peer-to-peer network computers communicate with each other as equals Each computer is responsible for
sharing its own resources to others• files, application programs, or devices
– printers, modems …setting up and maintaining its own securityaccessing the network resources it needs
• find out where the resources are,
• what security is required
called workgroup in Windows environment
Chapter 9 Designing a Network
9.1.1 Peer-to-peer Model
Chapter 9 Designing a Network
9.1.2 Client/Server Model
Client/server network network resources are
centrally managed by one or more servers.
Chapter 9 Designing a Network
A. Servers
Server responsible for shared resources
making them availablemanaging themenforcing the security
Dedicated servers are high performance computers with fault-tolerant features
Chapter 9 Designing a Network
A. Servers
Services include the following: Authentication and security File storage and sharing Printer sharing E-mail services Web hosting Proxy services Application services FTP services Telnet services Dial-in and dial-out services Fax services DHCP services VPN services Video streaming services
Chapter 9 Designing a Network
A. Servers
Directory service manage the scattered services on a network enables users to browse all the resources easily any changes will update the directories on all servers
e.g. adding a new user, or removing a printer
Chapter 9 Designing a NetworkA. Servers
1. Authentication server
Authentication server also called directory server or domain controller maintains a security database
to keep all the users’ accounts to controls their access level
authenticates users when they log in Member servers
servers other than the authentication server host a service or resource
but do not participate in maintaining the security
Chapter 9 Designing a NetworkA. Servers
2. File server
File server provides a centralised location for storing files with a shared directory or disk drive Security control includes
who can make access to each directory what kinds of access.
locks a shared file which is being editedexcept for a multi-user database
Chapter 9 Designing a NetworkA. Servers
3. Print server
Print server manages one or more printers allows a shared printer to be accessed by authorised users
A shared printer may be connected to a dedicated printer server
a small box with a fixed IP address computer
this requires the computer to be turned on hub
this requires the printer to have a built-in NIC
Chapter 9 Designing a NetworkA. Servers
4. Mail server
Mail server provides e-mail services to users each user has two mailboxes, storing
incoming mails, and copies of sent mails
SMTP serverfor sending outgoing mails
POP3 (IMAP) serverfor storing incoming mails
Chapter 9 Designing a NetworkA. Servers
5. Web server
Web server stores the contents of Web pages
of authorised users
entertains requests from other users on the Internet by delivering the Web pages
The IP address and the URL of a Web server should be made known to DNS servers
Chapter 9 Designing a NetworkA. Servers
6. Proxy server
Proxy server improves the efficiency of Internet access by caching
visited Web pages filters Web pages contents
to prevent users from accessing certain sites.
Chapter 9 Designing a NetworkA. Servers
7. Application server
Application server provides remote computing for clients Typical example: Database server
maintains multi-user databasesruns Database Management System (DBMS)
• to handle data requests from the clients
Chapter 9 Designing a Network
B. Clients
Client also called workstation in client/server environment a computer that requests services from a server uses a desktop OS with appropriate networking software
Chapter 9 Designing a Network
9.1.3 Pros/Cons of Peer-to-peer Model
Advantages of Peer-to-peer
1. Less expensive hardware can be used Dedicated servers not required
2. Easy to set up No need to set up servers
3. Expensive OS is not required NOS is more expensive than a desktop OS
4. Smaller chance of failure of the entire network If a server fails, the entire network would fail.
Chapter 9 Designing a Network
9.1.3 Pros/Cons of Peer-to-peer Model
Disadvantages of Peer-to-peer1. Insecure
desktop OS are not built to be securesecurity is done using password instead of user rights workstations are administered by users
2. Difficult to backup Not easy to backup data in many workstations
3. Difficult to maintain version control Users tend to store documents on a number of different
machines.
4. Difficult to manage users each workstation his its own set of user accounts
Chapter 9 Designing a Network
9.1.3 Pros/Cons of Client/Server
Advantages of Client/Server 1. Very secure
NOS are designed to be secure servers can be locked physically centrally placed data are easier to manage and track
2. Better workstation performanceDedicated servers handle all the resource sharing tasks
3. Centralised backup Backing up data in a centralised location is easier
4. More reliable servers have fault-tolerant features
5. Easier user managementa single database to keep user accounts
6. Single user logon
Chapter 9 Designing a Network
9.1.3 Pros/Cons of Client/Server
Disadvantages of Client/Server 1. Require professional administration
to set up and manage.
2. More hardware-intensiveDedicate server is expensive
3. Expensive NOSNOS is more expensive than desktop OS
Chapter 9 Designing a Network
9.2 Network Performance
The performance of a network refers to efficiency in data transmission the amount of tasks it can handle
Bottleneck reduces network performance part of a network where the capacity cannot meet the
required data flow. caused by
slow servercable of low bandwidthpoor network designadoption of a poor technology
Chapter 9 Designing a Network
9.2.1 Server performance
A. Efficiency of Hardware number of CPUs and their clock speeds memory size and speed disk drive capacity and speed bus width cache memory size
B. Amount of Services do not overload a server, otherwise bottleneck will occur
Chapter 9 Designing a Network
9.2.2 Network Traffic and Backbone
Bandwidth maximum rate of data transfer of a network channel To improve the bandwidth, use
full-duplex devices better cable
Network traffic the amount of data flow in each second may also be caused by a hub
Chapter 9 Designing a Network
9.2.2 Network Traffic and Backbone
Network throughput the amount of actual data flow in each second
a high network traffic may not mean high throughput• e.g. hub-based network.
Backbone of a network the circuit (including a switch and cables) that links up
smaller network segments traffic most busy
Backbone’s bandwidth should be 10 times the segments connected to it
Switches should be used in backboneFiber-optic cable is the best choice
Chapter 9 Designing a Network
9.2.2 Network Traffic and Backbone
Chapter 9 Designing a Network
9.2.3 Technology adopted
A. Protocols The protocols not only affect how a network
communicates, but also its performance. should conform with popular standards, like OSI and
IEEE. TCP/IP
breaks message into packetsthe bandwidth of connecting paths can be fully utilised
Chapter 9 Designing a Network
9.2.3 Technology adopted
B. Topology and hardware Hub-based star topology works well for small networks
only Switched-based star topology is currently the best choice.
C. Network Operating System newer versions are more efficient
always update the NOS patch
Chapter 9 Designing a Network
9.3 Network Plan
Need Analysis finding out the features that justify setting up a network
improved communicationsimproved information sharing and delivery improved sharing of data across multiple types of computersimproved security and access controls for sensitive dataeasier sharing of job assignmentseasier access to applicationsimproved system managementeasier to perform backups easier to expand
Chapter 9 Designing a Network
9.3 Network Plan
Design and Cost AssessmentWhat application programs do the system run?How many users are there on the network?How much storage space is required?How much bandwidth is required?What network services are required?What is the budget?Will the plan cater for future expansion?
Chapter 9 Designing a Network
9.3 Network Plan – A. Smallest network
Chapter 9 Designing a Network
9.3 Network Plan – B. Home networking
Chapter 9 Designing a Network
9.3 Network Plan – C. A small office with 15 users
9.3 Network Plan – C. A small office with 15 users
Chapter 9 Designing a Network
9.3 Network Plan – D. A medium-sized office in 2 floors
9.3 Network Plan – D. A medium-sized office in 2 floors
Chapter 9 Designing a Network
9.3.4 Documentation
Address List Cable Map Contact List Equipment List Network History Network Map Policies and procedures Server Configuration Software configuration Software Licensing User administration Password List