Server administration

Servers are computers that are explicitly set-up to provide services to other computers on the network.

Therefore server administration is the task of managing, upgrading and maintaining these servers and making sure that all systems are humming along.

We need to know other discipline to administer a

server...

Network Basics

• the logical structure and operating principle of a network system and defines the communication protocols required for real-world data exchange

• It determines “hierarchical structures” according to each classification and specifies protocols and interfaces between layers of the hierarchical structure.

• within the network architecture, all the network's physical elements are modeled and structured and treated as a logical network

• Main components are: node i.e. hardware such as computers and

communication equipment link i.e. communication lines process i.e. application programs

If the architecture is the same, a system can be built by adjusting the interfaces even when products from different manufacturers are combined

Employing a system compliant with standard interfaces makes it easy to develop, expand and maintain the system

Even independently developed systems can be easily integrated

The entire network can be treated locally

Open Network Architecture Vendor-specific proprietary network architecture

Open Systems InterconnectionTransmission Control Protocol/Internet Protocol

Systems Network Architecture (SNA) – IBM

DECnet - DEC

IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange) – Novell

Apple Talk – Apple Corporation

Network Topology

nodes are connected in a closed loop by communication lines

transmission lines are short and easily controlled

if just one node fails, it might affect the entire network

two or more paths lead to each node so that that the overall structure becomes that of a mesh

even if a node fails, that node can be bypassed by routing meaning that the reliability of this type of network is high

each node is connected to a central node in star shaped configuration

even if one node fails, this will have no effect on the overall systems but if the central node fails, the entire network will no longer be functional

all nodes are connected to a common communication line

makes it easy to add or remove nodes without affecting the overall system and at the same time it is economical

when there are many nodes and the traffic load increases data collision may occur on the common communication line and the transmission efficiency may deteriorate

several child nodes are connected to a parent node

also called cascade connection

There are three typical connection methods that are used in accordance with what best suits the communication distance and data load, etc. These are: • Point-to-point connection• Multipoint connection• Switched connection

the computer is connected one-to-one to each terminal through a leased line communication lines

appropriate if heavy traffic between two points is required

multiple branching devices are connected sequentially to the same communication line

This configuration allows construction of a network that is cheaper than using the point-to-point configuration when the communication distance is long and the data traffic is light.

Since the main communication line is shared, other terminals have to wait while one is transmitting data

the lines from several terminals are connected to a concentrator, which is connected to the host computer through a high-speed line

No matter what kind of software is running on a network and regardless of what kind of data is transmitted, problem-free data communication will be possible on the OSI complaint network.

Application 7 Provides communication services required for applications. i.e. file transfer and management, remote database acces, virtual terminal

Presentation 6 Data representation, format translation and mapping

Session 5 Performs dialog management. •Dialog management controls and manages the data flow between application and systems by emplying the end-to-end data transfer capabilities provided by the transport layer.

Transport 4 Guarantees the quality of data transfer between system ends

Network 3 Concerned primarily with path selections and relays

Data-link 2 Ensures transparent and error-free data transmission by using transmission controls such as high-level data link control, establishment of data-link connection, error control, etc.

Physical 1 Transmits electric signals using transmission media