Network Layer
In this layer the data and traffic signal being routed. All router function perform on this layer. The main responsibility of layer is to route packet from source to destination. If two computer connected in same network or link then no need of network layer they can communicate directly. Network layer work when router is involve because it routes different network source to destination and work as controller. It also divided message into packet for sending and assemble packet to message when received for upper layers.
As transport layer two protocols works that are TCP and UDP,we discuss basic difference in that post.Same as transport layer Network layer also have many protocols but main is IP(Internet protocol). This IP we known with TCP and called both together TCP/IP. IP provide many feature but most important feature is addressing and routing. To understand how IP works on this layer we describe an example of postal mail service below.
Let you have two friends one live within the city and other live some other state or province city. You write letter to both friends. You write address and paste a stamp on envelope as you treated both letter equally so you can post these letter.First you drop the letter in mailbox or post office box to expect postal mail service deliver them to address you write. However the postal service that receive your letter act differently, they treated each letter differently, so they separated letters for process how to deliver each letter to destination. For the letter within the city the service just sent this letter through truck or other local post office.Now the letter sending other state city need other processes. The postal service send the letter to other post office then another post office then another so on until it reaches the destination. At reaching each post office the letter is going through process as the first stage of service. For sending to other post office the service has many regular routes with many different transport like van,trucks,bigger trucks train, planes and boat,ships etc. Now think about difference between you and postal service. You just hope that postal service deliver the letter to address. You does not know the process and route details how letter reaches to destination. Network layer IP perform as postal service in the network, as postal service decide about how letter deliver same as network layer IP decide how packet is transferred from source to destination computer. Router perform as post office and IP guided the route which computer is its destination. Router have also a mechanism to decide which route is best we brief it when we discuss router.Network layer contain some function that execute following processes.
Network layer convert logical address to physical address and vice versa work with circuit and packet switching.
It divided larger messages into small packet.
Network layer also have function that develop a mechanism for routing packet to destination. Router and gateway works on this layer.
It also have connection service function that responsible for flow control,error handling and packet numbering sequence.
As transport layer two protocols works that are TCP and UDP,we discuss basic difference in that post.Same as transport layer Network layer also have many protocols but main is IP(Internet protocol). This IP we known with TCP and called both together TCP/IP. IP provide many feature but most important feature is addressing and routing. To understand how IP works on this layer we describe an example of postal mail service below.
Let you have two friends one live within the city and other live some other state or province city. You write letter to both friends. You write address and paste a stamp on envelope as you treated both letter equally so you can post these letter.First you drop the letter in mailbox or post office box to expect postal mail service deliver them to address you write. However the postal service that receive your letter act differently, they treated each letter differently, so they separated letters for process how to deliver each letter to destination. For the letter within the city the service just sent this letter through truck or other local post office.Now the letter sending other state city need other processes. The postal service send the letter to other post office then another post office then another so on until it reaches the destination. At reaching each post office the letter is going through process as the first stage of service. For sending to other post office the service has many regular routes with many different transport like van,trucks,bigger trucks train, planes and boat,ships etc. Now think about difference between you and postal service. You just hope that postal service deliver the letter to address. You does not know the process and route details how letter reaches to destination. Network layer IP perform as postal service in the network, as postal service decide about how letter deliver same as network layer IP decide how packet is transferred from source to destination computer. Router perform as post office and IP guided the route which computer is its destination. Router have also a mechanism to decide which route is best we brief it when we discuss router.Network layer contain some function that execute following processes.
Network layer convert logical address to physical address and vice versa work with circuit and packet switching.
It divided larger messages into small packet.
Network layer also have function that develop a mechanism for routing packet to destination. Router and gateway works on this layer.
It also have connection service function that responsible for flow control,error handling and packet numbering sequence.
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