OSI MODEL

OSI is the layer model for the network system designed by ISO .  OSI enable device to network to communicate with each other.

Application Layer-   The Application Layer is the top most layer of the OSI  model.  It provides network access to application and to users.  The application layer to provide service with which users can access all type of network  so application and user use these service to communicate with device and remote application.

Service- 

FTAM(File Transfer and Management)-  Using the application user can access file in a remote host it also enable the user manage file from remote host .

Mail Deliver Box-  Using the application email can be forwarded to another computer “Massage Handling Service” is the OSI protocol use for transfer mail over the internet.

Directory Service- Directory service is a source of information.    A about  such as people organization and file.

Network Virtual Terminal-   It is a software version  a physical terminal version Terminal using user can log on  the computer.  It is remotely connected on the network.

Protocol use in Application Layer- 

TCP-   A connection oriented protocol that is defined at the transport layer of the OSI reference model provide reliable delivery of data.

FTP-  The TCP/IP protocol used for transmitting files between network nodes .  It supports a brand range of file types and is defined in RFC959.

DHCP-   DHCP is used automatically configured a host during boot up on a TCP/IP network and also to change setting while the host is attached.

            This means that you can stored all the available IP address in a central data base along with information such as the subnet mask Gateways DNS server etc.

SMTP-   A protocol used on the internet to provide electronic mail Service.

DNS-   DNS is used to convert user friendly names to IP address.  They are two Zones in DNS.

 Device-  No Device use.

Presentation  Layer-  The Presentation Layer is sixth form the layer top the main function of this layer is the presentation of data.  There are situations when data sent from one system to another system has to be viewed in a different way.  Translation is the main function of the presentation layer the other function is rarely used.

Translation-     In a network there can be many type of computers, for example presentation layer is a mixed systems, we have two different type of systems, in the same network.  One is the MAC Machine and other is the UNIX machine.  Character set in both machine is different, but the presentation layer hide the different.

Compression-  This is an optional function, but it can be done by the presentation layer to improve performance.

Encryption-  We can use Presentation Layer encryption function to ensure security SSL is the one of the popular encryptions used in the Presentation layer.

Protocol-  RIP, SNMP AND DNS

Device-  Gateway

Session Layer-   It control the communication between the hosts the session layer is responsible to establish on connection to the user.

Service-

 Dialog Controller

Synchronization

Closing the Session

Dialog Box-   It allow to device to enter into dialog controller these dialog can take place in there in half duplex and full duplex.

Synchronization-  If the device  is sending he file 100 pages to ensure that these 100 pages without error they are greed link a sending data.

Closing the Session-  Ensure that the data transfer is completed before the session closed.

Protocol-  DNS, NETBIOS, SNTP, SMTP, FTP

Transport Layer-   Transport layer is responsible for source and the destination delivery the entire massage he transport layer ensure that the entire massage he arrived the destination at the computer.

Service- 

Segmentation and Reassembling

Connection Control

Error Control

Segmentation and Reassembling-  A Massage is delivered in to segment with each segment having a sequence number when they arrived that the destination with a sequence number. The transport layer Reassemble the massage.

Connection Control-  There are two type of connection control.

 Connection Oriented

 Connection Less

Error Control-  Two type of Error Control.

Error Deduction

Error Correction

Protocol-   TCP & UDP

Device-   Gateway

Network Layer-  This is responsible for routing and logical addressing.  A Network layer is provide service such as assigning IP address for the delivering the packet.

Routing-  Routing is the selecting the best path for the packet.

 Service-

 Logical Addressing

Routing

Source of destination delivery

Logical Addressing-   The data link layer provide physical addressing which is useful of local Network When the packet is forward a device out of a network be required other addressing scheme o identify source and destination when we use 32 bit logical address.

Routing-   Routing is the process of where in a proper path define for the packet to reach destination routing.

There are two type of routing.

Static Routing

Dynamic Routing

Static Routing-   In a static routing he root o be forwarded by a packet its already sets by the network administration.

Dynamic Routing-   The route to be forwarded by a packet is decided at time of transmission of the packet.

Protocol- 

 IP

ARP

RARP

ICMP

Device-   Router

Source & Destination delivery-   Transfer from the source to its destination delivery.

Data Link Layer-  It handle data transfer between network layer and physical layer data unique data link layer its called as frame.

Service- 

Framing

Physical Addressing

Error Control

Exists Control

Flow Control

Protocol- 

HDLC

SDLC

Device- 

Bridge

Switch

Physical Layer-  It is responsible to transmit up bit over the physical medium.  A bi is a short of a binary digit, and is the smallest unit of information on the computer.  The bit can be either 0 to 1. 

Service- 

Encoding

Transmission Rate

Transmission Mode

Note-  No protocol working in Physical Layer.

Device-   Router and Hub

Data Link Layer For Ethernet-   Ethernet is data link layer responsible for physical source and destination addressing.   The packet in to frame for transmitting the network  layer.