7 LAYER OSI

good morning,good afternoon,or good night now i'll try explain about 7 layer OSI

Seven layer OSI networking model's :
--- layer 7(layer aplication) ---
layer aplication is the layer that most network users are exposed to,and is the level which human comunication happens.HTTP,SMTP and FTP are all applications layer protocol.the human sits above at the layer,interacting with application.

--- layer 6 (layer presentation ) ---
the layer presentation deal with data representation.before it reaches the application.this would include MIME encoding,data compration,formating check,byte ordering,etc.

--- layer 5 (layer session ) ---
the session layer manages the logical communications session between applications.NetBIOS and RPC are two example of a layer five protocol.

--- layer 4(layer transport) ---
the transport layer provides method reaching a particular service on a given network node,for example of protocols thet oprate at this layer are TCP and UDP,some protocols at the transport (such as TCP) ensure that all of the data has arrived at the detination,and is ressembled and delivered to the next layer in the proper order,UDP ins a conectionless protocol commonly used for video and audio streaming.

--- layer 3 ( layer network ) ---
IP(internet protocol )is the most common network layer protocol,this is the layer where routing accours.packets can leave the link local network and be retransmiters on other network,routers perform this function on a network by heving at least two network interface,one of the earch of the network to be interconected.. Nodes on the Internet are
reached by their globally unique IP address. Another critical Network Layer protocol is ICMP, which is a special protocol which provides various management messages needed for correct operation of IP. This layer is also sometimes referred to as the internet layer.

---( layer data link ) ---
Whenever two or more nodes share the same physical medium (for example, several computers plugged into a hub, or a room full of wireless devices all using the same radio channel) they use the Data Link Layer to communicate. Common examples of data link protocols are Ethernet, Token Ring, ATM, and the wireless networking protocols (802.11a/b/g). Communication on this layer is said to be link-local, since all nodes connected at this layer communicate with each other directly. This layer is sometimes known as the Media Access Control (MAC) layer. On networks modeled after Ethernet, nodes are referred to by their MAC address. This is a unique 48 bit number assigned to every networking device when it is manufactured.

---( layer phsycal )---
phsycal layer is the lowest layer in the OSI model, and refers to the actual physical medium over which communications take place. This can be a copper CAT5 cable, a fiber optic bundle, radio waves, or just about any other medium capable of transmitting signals. Cut wires, broken fiber, and RF interference are all physical layer problems.


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