Network Operating System (NOS):
Every computer needs an operating system; they may be UNIX,
DOS, OS/2 or NOS. if you want to run our computer properly in a network
than NOS must be loaded properly. Networks Operating System sometime
fails internally due to the bugs in codes. There can also be problems
due to the drivers that access the Network Interface Card (NIC) or
adapters. Apart from the above, may failures occur due to applications
designed to run on server when they access the NOS services with illegal
function calls
The network operating system has two basic components: the network server operating system itself and the workstation. The network server operating system runs. Within the server machine and processes all the services the network operating system usually supplied by a manufacturer OEM, sometimes building on a general-purpose operating system . The workstation components run in the workstation and establish the connection with the network server and control the flow of communication.
OSI Model:
The international organization for standardization (ISO) develops the OSI (Open System Interconnection) model in 1997. the OSI model defines the rules that apply to the following issues:
How Network devices contact each other and how they understand the language of each other and how thy communicate with each other.
Methods by which a device in which a network know when to transmit data and when not to.
Methods to insure that network transmissions are received correctly and by the right recipient.
How the physical transmission media are arranged and connected.
How to ensure that network devices maintain a proper rate of data flow.
How bits are represented on the network media.
The OSI model is nothing tangible it is simply a conceptual framework. The OSI model doesn’t perform functions in the communiation process. The actual work is done by the appropriate software and hardware the OSI model protocols will handle those task. The OSI model consists of seven layers.
1. Application layer:
The application layer is eh topmost layer of the OSI model and it provides services that directly support user application such as database access,, e-mail and file transfer. It also allows application to communicate with application on other computers as though they were on the same computer. This application layer includes the basic service from any network including dealing with files. Sending messages to other network.
2. Presentation Layer:
The presentation layer translates the data access from the application layer in the language understandable by network or computer. The presentation layer does protocol conversion, data translation, compression and encryption, character set of conversion and the interpretation of graphics commands. The network redirector operates at this level . the network redirector is what makes the files on a file visible to the client’s computer.
The network redirector also makes remote printers act as though they are attached to the local computer.
This layer is responsible for ensuring that data is in a form everyone can understand and work with takes the data from the session layer and passes it along to the application layer.
3. Session Layer:
This layer establishes a session in which the communication has done between two computers. This layer provides services such as name look up and security to allow two programs to find each other and established he communicate on link the session layer also provides for data synchronization and check pointing so that in the event of network failure, only the data sent after the point of failure need by resend this layer also controls the dialogue between two processes after mining who can transmit and who can receive at what point during the communication. Session layer protocol establishes and manages session using a data’s taken toe determine which can talk and when talk to communicate the computer one to others all data packet’s information knows as token.
4. Transport Layer:
The network layer ensures that packets are delivered error free, in sequence, and with no loses or duplication it provides error free transmission of data from one computer to another. The transport layer message from the session layer into packet to be sent to the destination computer and reassembles packets into message to be presented to the session layer the transport layer typically sends and acknowledgement to the originator for message receive.. the transport layer is home to a number of protocols: TPO, TP1,TP2 and so on. These layer handle the packet of message and reassembly and error recovery.
5. Network Layer:
The network layer decides the best route for data transfer, which are adopted from transport layer and forwarded packets of devices that are further away then a single link. The network layer translates logical network addresses into physical machine addresses. This layer also determine the quality of service such as the priority of the message and the route message will take if there are several ways a message can get to it’s destination.
The network layer also break large packets into small chunks if the packet is larger than the largest data frame the data link layer will accept the network resembles the hunks. Into packets at the receiving in the protocols at this layer may choose a specific route through an interact work to avoid the access traffic caused by sending date over networks.
Networks layer defines how the network moves information from one device to another. This layer corresponds to the hardware interface function BIOS of and individual PC, because it provides a common software interface.
6. Data Link Layer:
The data link layer provides for the flow of data over a single link from one device to another. It accepts packets from the network layer and packages the information into data unit called frames to be presented to the physical layer of transmission. The data link layer adds control information such as frame types routing to the data being sent. Actually this layer provides for the error free transfer of frames from one computer to another. a cycle redundancy check added to the data frame can detect damaged frames. The data link layer can also detect when frames are lost and request that those frames be sent again. This layer further divided into two sub-layer,
a. logical link control, which establish and maintains links between the communicating devices.
b. Media access control (MAC), which controls the way multiple devices share the same media channel.
If defines how information gains access to the wiring system. The data link layer defines the basic protocol used in the local network. If decide and send a message over the cable at any given item the form of messages and the transmission method of those message.
Physical Layer:
The physical layer is simply responsible gains access to the wiring system. The data link layer defines the basic protocol used in the local network. if decide and send a message over the cable at any given item, the form of messages and the transmission method of those message.
The following item are addressed at the physical layer.
Network connection type
Physical topologies
Analog and Digital signaling.
Base band and Broad band transmission.
Termination.
The first layer of the OSI Reference Model is the physical layer, which defines the basic hardware of network, which is the cable that conducts the flow of information between the devices linked by the network. this layer defines the type of wire such as coaxial, twisted pair cable, length and connection and the interface of the cabling system.
The network operating system has two basic components: the network server operating system itself and the workstation. The network server operating system runs. Within the server machine and processes all the services the network operating system usually supplied by a manufacturer OEM, sometimes building on a general-purpose operating system . The workstation components run in the workstation and establish the connection with the network server and control the flow of communication.
OSI Model:
The international organization for standardization (ISO) develops the OSI (Open System Interconnection) model in 1997. the OSI model defines the rules that apply to the following issues:
How Network devices contact each other and how they understand the language of each other and how thy communicate with each other.
Methods by which a device in which a network know when to transmit data and when not to.
Methods to insure that network transmissions are received correctly and by the right recipient.
How the physical transmission media are arranged and connected.
How to ensure that network devices maintain a proper rate of data flow.
How bits are represented on the network media.
The OSI model is nothing tangible it is simply a conceptual framework. The OSI model doesn’t perform functions in the communiation process. The actual work is done by the appropriate software and hardware the OSI model protocols will handle those task. The OSI model consists of seven layers.
1. Application layer:
The application layer is eh topmost layer of the OSI model and it provides services that directly support user application such as database access,, e-mail and file transfer. It also allows application to communicate with application on other computers as though they were on the same computer. This application layer includes the basic service from any network including dealing with files. Sending messages to other network.
2. Presentation Layer:
The presentation layer translates the data access from the application layer in the language understandable by network or computer. The presentation layer does protocol conversion, data translation, compression and encryption, character set of conversion and the interpretation of graphics commands. The network redirector operates at this level . the network redirector is what makes the files on a file visible to the client’s computer.
The network redirector also makes remote printers act as though they are attached to the local computer.
This layer is responsible for ensuring that data is in a form everyone can understand and work with takes the data from the session layer and passes it along to the application layer.
3. Session Layer:
This layer establishes a session in which the communication has done between two computers. This layer provides services such as name look up and security to allow two programs to find each other and established he communicate on link the session layer also provides for data synchronization and check pointing so that in the event of network failure, only the data sent after the point of failure need by resend this layer also controls the dialogue between two processes after mining who can transmit and who can receive at what point during the communication. Session layer protocol establishes and manages session using a data’s taken toe determine which can talk and when talk to communicate the computer one to others all data packet’s information knows as token.
4. Transport Layer:
The network layer ensures that packets are delivered error free, in sequence, and with no loses or duplication it provides error free transmission of data from one computer to another. The transport layer message from the session layer into packet to be sent to the destination computer and reassembles packets into message to be presented to the session layer the transport layer typically sends and acknowledgement to the originator for message receive.. the transport layer is home to a number of protocols: TPO, TP1,TP2 and so on. These layer handle the packet of message and reassembly and error recovery.
5. Network Layer:
The network layer decides the best route for data transfer, which are adopted from transport layer and forwarded packets of devices that are further away then a single link. The network layer translates logical network addresses into physical machine addresses. This layer also determine the quality of service such as the priority of the message and the route message will take if there are several ways a message can get to it’s destination.
The network layer also break large packets into small chunks if the packet is larger than the largest data frame the data link layer will accept the network resembles the hunks. Into packets at the receiving in the protocols at this layer may choose a specific route through an interact work to avoid the access traffic caused by sending date over networks.
Networks layer defines how the network moves information from one device to another. This layer corresponds to the hardware interface function BIOS of and individual PC, because it provides a common software interface.
6. Data Link Layer:
The data link layer provides for the flow of data over a single link from one device to another. It accepts packets from the network layer and packages the information into data unit called frames to be presented to the physical layer of transmission. The data link layer adds control information such as frame types routing to the data being sent. Actually this layer provides for the error free transfer of frames from one computer to another. a cycle redundancy check added to the data frame can detect damaged frames. The data link layer can also detect when frames are lost and request that those frames be sent again. This layer further divided into two sub-layer,
a. logical link control, which establish and maintains links between the communicating devices.
b. Media access control (MAC), which controls the way multiple devices share the same media channel.
If defines how information gains access to the wiring system. The data link layer defines the basic protocol used in the local network. If decide and send a message over the cable at any given item the form of messages and the transmission method of those message.
Physical Layer:
The physical layer is simply responsible gains access to the wiring system. The data link layer defines the basic protocol used in the local network. if decide and send a message over the cable at any given item, the form of messages and the transmission method of those message.
The following item are addressed at the physical layer.
Network connection type
Physical topologies
Analog and Digital signaling.
Base band and Broad band transmission.
Termination.
The first layer of the OSI Reference Model is the physical layer, which defines the basic hardware of network, which is the cable that conducts the flow of information between the devices linked by the network. this layer defines the type of wire such as coaxial, twisted pair cable, length and connection and the interface of the cabling system.
