Lec1: Network Management (Review) Edited by: Nada Alhirabi

Outline Rules for choosing the most suitable type of network What is the network? Goals of the network Network Classification By Distance By resource access By topology By transmission medium Rules for choosing the most suitable type of network Devices for Exchanging & Transferring Data Network Interface Card (NIC) Modem Hub Repeater Bridge Router Gateway

What is the network? Connecting two or more computing devices using hardware and software to manage connection between devices so that it is possible to: Share resources. Exchange information. Resources refers to: Hardware and software components that is prepared to be used for networks. Such as: hardware(printer, hard disk, processor...etc), software and systems (database management systems, extensive programs) Data (video, audio, voice, data,…etc)

Goals of Networks Sharing different resources regardless of the distance. Using secondary computers in the case of any failure or malfunction. Speeding up complicated operations such as: (math applications, simulation) by using multiple computers and processors.

Requirement for building a network At least two computers Network Interface Card (NIC) Transmission media (wired or wireless) Switch, router or hub Application software: Operating System. Network operating system. Network management system. Network protocols.

Network Classification By Distance: Local Area Network (LAN) Metropolitan Area Networks (MAN) Wide Area Networks (WAN) By resource access: Peer-to-Peer network Server based network By topology Bus Ring Star Mix By transmission medium: Wired Wireless

Local Area Network (LAN) Network computers are located relatively close to each other (few kilometers in distance). Limited to buildings owned by one organization. Advantages: Efficiency & speed in data transmission. Less errors. LAN components are cheap & easily available. Disadvantages: Difficulty to link different networks due to the large number of rules. Limitation in the geographic area.

Metropolitan Area Network (MAN) Used to cover medium size area around few kilometres) to link computers in the same city such as universities. Advantages: Fast & efficient in data transmission. Possibility to connect computers in one city. Disadvantages: Rarely used. Difficulty in maintaining MAN due to its large size.

Wide Area Network (WAN) Consist of group of LANs connected to each other to cover large geographic area. Advantages: Possibility to connect thousands of computers. Possibility to transfer large number of data. Possibility to connect different LANs owned by different organizations. Disadvantages: Requires expensive hardware & software. Hard to operate Requires special kind of programs.

Classifying Network by Resource Access Peer to Peer (P2P) Networks Client/Server Network

Peer To Peer (P2P) Network Peer-to-peer network architecture allows to connect two or more computers in order to share their resources. Example: C A->B: When A sends request to use B’s projector. A: the client B: the server C->A: When C sends request to use A’s printer. C: the Client A: the server A B C->A: When C sends request to use A’s printer. C: the Client B: the server

(P2P) Advantages & Disadvantages Inexpensive. Does not require additional program to manage he network. Does not require high quality devices. Easy to install & operate. Disadvantages: Time & effort consumption due to the decentralized management. Not Secured. Poor Performance when number of users increase.

(P2P) Network Management Every user in the P2P network is responsible for: Managing his own computer Obtaining which resources will be shared in the network Obtaining the sharing permission (read – write – read &write) for the shared resources.

Client/Server Networks Client/Server Networks: a network in which one centralized, powerful computer (called the server) is connected to many less powerful personal computers or workstations (called clients). Server: is a specially designed and very powerful computer with large storage, fast processor & large memory. Types of Servers: File Servers. Printer Servers. Application Servers. Communication Servers. Database Servers.

Client Server Networks A wants to use the printer A sends request to the server. Server responds by putting pc A in the request queue. When it is A’s turn it uses the printer. C wants to use the database. C sends request to the server. Server responds by putting pc C in the request queue. When it is C’s turn it uses the printer. Server C A B Request Response

Advantages of Client/Server Networks Protecting data from loss and damage. Possibility to make scheduled backups. Possibility to increase number of users. The clients computers are inexpensive. Centralization of network resources in a single computer. Ease of data management and control. Highly secured. Why? because the server allows only special persons to control the management of network resources to issue permissions for users to use the resources that they need.

Disadvantages of Client Server Networks Requires expensive programs. Requires powerful computer to be used as a server. Requires network management. When the server fails the entire network stops.

Client/Server Network Management Client Server networks are managed using network management systems installed on the server computer so that it controls everything about the network including: The network performance Statistical reports Monitoring clients Monitoring resources.

Network Classification based on its topography

Bus Group of computer devices connected to each other along the same backbone cable. Advantages: Inexpensive. Doesn’t require a lot of devices to work. Easy to install and manage. Disadvantages: When the backbone cable is broken the whole network stop. Increasing number of users in the network may lead to collisions. limited expansion Ethernet example of a technology that uses bus topology.

Ring A computer network where each computer & device are connected to each other forming a large. Data is sent around the ring until it reaches its final destination (Token Ring Approach) Advantages: Prevents data collisions. Guarantee data arrival. Give an equal chance of sending. Disadvantages: If one of the connected devices fail the whole network stop. Very Slow. Token Ring & FDDI are examples of technologies that uses ring topology

Star Group of computer devices connected to each other with a central device. Advantages: Easy to install & maintain. Inexpensive. Uses twisted pair cables. Disadvantages: If the central device fails the whole network stop. Fast Ethernet is an example of a technology that uses star topology

Classifying networks based on transmission medium Wired Networks Networks that use wires as a transmission medium for transferring data: Coaxial cables Twisted Cables Fiber Optic Cables. Wireless Network Networks that uses the air as a transmission medium for transferring data. Radio signals Microwave signals Laser Signals Infrared signals.

Rules for choosing the most suitable type of network Size of the organization. Number of users in the network. Level of security. Type of the organization. Level of management support required by the organization. Requirement for users of the network. Budget for the network.

Devices for Exchanging & Transferring Data Network Interface Card (NIC) Modem Hub Passive hub Active hub Intelligence hub Repeater Bridge Router Gateway

Network Interface Card (NIC) Network Interface Card (NIC): is a computer circuit board or card that is installed in a computer so that it can be connected to a network

The MODEM MODEM: is a device that contains group of electronic circuits & converts analog signals into digital signal & vice versa. Types of MODEMS: Internal: Part of the motherboard. External: Device connected to the computer using a serial port.

Hub The most basic networking device that connects multiple computers or other network devices together. Has no intelligence (No routing tables) Can detect collisions Hub works in the physical layer (1st layer) of the OSI model. Hub has three basic types: Passive hub Active hub Intelligence hub تتصل أجهزة الكمبیوتر في معظم أنواع الشبكات المحلیة- عدا وهو عبارة عن جهاز (coaxial cables)) شبكات الإیثرنت التي تستخدم كوابل محوریة ،(hub) یقوم بدور نقطة وصل مركزیة بین أجهزة الشبكة، وهو یدعى الموزع الشبكي ببعضها. (segments) ووظیفته هي ربط قِطِع الشبكة ومن أنواع الموزِّعات: . Passive Hub الموزع الخامل 􀁸 . Active Hub الموزع النشط 􀁸 . Intelligence Hub الموزع الذكي 􀁸 یمثل هذا النوع من الموزعات موزع للأط ا رف : " Passive Hub" (أ) الموزع الخامل السلكیة(مشترك) وهو یمثل عقدة اتصال ولا یكبر الإشارة ولا یحتاج لقدرة كهربائیة. یستقبل الإشارة ویعمل على تقویتها وٕاعادة : " Active Hub " (ب) الموزع النشط تولیدها مرة أخرى مثل مقوي الاشارة مما یسمح بمسافات اكبر بین اجهزة الشبكة. هو نوع من الموزعات الفعال : " Intelligence Hub " الموزع الذكي 􀂃 یقوم بوظائف اضافیة مثل توزیع البیانات حسب اهمیتها.

Hub Passive hub Active hub Intelligence hub Does not regenerate signals Does not strength signals Simply retransmit signals No electricity required Active hub Regenerate , strength & retransmit the signals Usually 8 - 12 Ports Require electricity Also Called ‘Multiport Repeaters’ Intelligence hub An active hub that have some network management capabilities.

Repeater It is a device that amplify & regenerate & retransmit the signal over the network. Allows network expansion because it can increase number of connected devices to the network. Repeaters work on the physical layer (1st layer) of the OSI model. Cannot be used with Ethernet or Token Ring Benefits for using repeaters: Strengthening & amplifying signals. Expanding networks.

Bridge A device that is used to connect components & devices of the network. Work on the Data link layer (2nd) of the OSI model. Could be used to expand the size of LAN networks. Have the ability to connect different types of cables (Twisted pair – Coaxial - ...etc)

Router A Router is a network device that forward packets from one network to another. It is a smart device that forwards packets based on: The current traffic conditions (load, line costs, bad lines, etc.). Internal routing tables (Intelligent ) Work on the Network layer (3nd) of the OSI model.

Different Types of Router Static Router: requires from the network administrator to install the routing table manually. Dynamic Router: Requires from the network administrator to install the routing table manually at the beginning only. After that the routing table is updated automatically & the router chooses the best routing path based on the routing protocol.

Gateway A network gateway is an internetworking system capable of joining together two networks that use different base protocols. A network gateway can be implemented depending on the types of protocols they support in: Software Hardware Or a combination of both. Network gateways can operate at any level of the OSI model. Able to convert the data from one format to another and from one encoding system to another