The Iso Osi model are explained below. The seven layers of the Osi model are:
- Application
- Presentation
- Session
- Transport
- Network
- Antiqua">Data Link
- Physical
1 Application layer:
[cable To A Serial Port]
This layer provides a means for the user to access information on the network straight through an application. Many user applications that need to narrate over the network interact with the Application layer protocol directly. The user applications are not part of Osi Application layer, use the networking services offered by the networking protocol suite. Application layer functions typically comprise identifying communication partners, and determining availability of required resources. Some examples of application layer implementations comprise Telnet, File change Protocol (Ftp), and uncomplicated Mail change Protocol (Smtp).
2 Presentation layer:
Presentation layer converts local host computer data representations into a approved network format for transmission on the network. On the receiving side, it changes the network format into the approved host computer's format so that data can be utilized independent of the host computer. Ascii and Ebcdic conversions, cryptography, and the like are handled here.
Examples of Presentation layer coding and conversion schemes comprise tasteless data representation formats, conversion of character representation formats, tasteless data compression schemes, and tasteless data encryption schemes.
Presentation layer implementations are not typically related with a singular protocol stack. Some customary standards for video comprise QuickTime and motion photo Experts Group (Mpeg). QuickTime is an Apple Computer specification for video and audio, and Mpeg is a approved for video compression and coding.
3. Session layer:
The session layer establishes, manages, and terminates communication sessions. communication sessions consist of service requests and service responses that occur in the middle of applications settled in dissimilar network devices. These requests and responses are coordinated by protocols implemented at the session layer. Some examples of session-layer implementations comprise AppleTalk's Zone information Protocol (Zip), and Decent Phase Session control Protocol (Scp).
4.Transport layer:
Transport layer is responsible for providing reliable service in the middle of the hosts. Upper layer datagrams are broken down into manageable datagrams and then approved header information (such as sequence number, port number, etc.) is added to the datagram before passing it on to the Network layer. Two frequently used vehicle protocols are the Tcp (Transmission control Protocol) and the Udp (User Datagram Protocol).
Important features of vehicle layer:
- Transport layer ensures reliable service.
- Breaks the message (from sessions layer) into smaller datagrams, and appends approved unit header information.
- Responsible for communicating with the Session layer
Important features of Tcp/Udp:
- Tcp/Ip widely used protocol for Transport/Network layers
- Tcp: (Transport control Protocol) Tcp ensures that a packet has reached its intended destination by using an acknowledgement. If not, it retransmits the lost messages. Hence, Tcp is called a connection oriented protocol.
- Udp (Universal Data gram Protocol): Udp plainly transmits packets over the internet. It does not wait for an acknowledgement. It is the accountability of upper layer protocols to ensure that the information had reached the intended partner(s). Hence, Udp is often called connectionless protocol.
- Application programs that do not need connection-oriented protocol generally use Udp.
5. Network layer:
Network layer is responsible for the routing of packets straight through the whole network. The layer uses logical addressing for this purpose. Note that the bodily address (like Mac address) keeps changing from hop to hop when a packet travels from source to destination. As a result, an address that doesn't change is required to ensure continuity in the middle of hops. This is nothing but logical address. For Ip networks, Ip address is the logical address; and for Novell network, Ipx address is the logical address, and so on. This layer also provides for congestion control, and accounting information for the network. Ip (Internet Protocol) is an example of a network layer protocol.
6. Data link layer:
Data link layer provides delivery of information frames in the middle of communicating partners. This layer is responsible for flow regulation, error detection and correction, and framing of bits for transmission. The network data frame is made up of checksum, source address, destination address, and the data itself. The largest frame size that can be sent is known as the maximum transmission Unit (Mtu).
Important features of Data link layer:
- Logical Link control (Llc): Defines how data is transferred over the cable and provides data link service to the higher layers.
- Medium access control (Mac): Controls media access by regulating the communicating nodes using pre-defined set of rules. (i.e. Token passing, Ethernet [Csma/Cd] all have Mac sub-layer protocol).
Different Data link layer protocols define dissimilar network and protocol characteristics, along with bodily addressing, network topology, error notification, sequencing of frames, and flow control. bodily addressing (as opposed to logical addressing) defines how devices are addressed at the data link layer. The protocols used in Data link layer are Slip, Ppp, and Cslp.
7. bodily layer:
This is the bottom-most layer of the Osi model. The bodily layer handles the bit-level communications over the bodily medium. The bodily medium could be made up of wired electrical signals, or light, or radio (wireless) signals. bodily layer specifications define characteristics such as media, data rates, maximum transmission distances, and bodily connectors.
Some of the important standards that deal with bodily layer specifications are:
Rs-232(for serial communication lines), X.21, Eia 232, and G730.
Physical layer and Data link layer implementations can be categorized as either Lan or Wan specifications.
Seven Layers of Iso Osi Model