osi – Networking: Difference between Transport layer and Networking Layer

osi – Networking: Difference between Transport layer and Networking Layer

These are levels of abstraction.

Transport Layer is where the decision to use TCP/UDP is made. Among commonly used protocols in this layer, TCP is reliable, UDP isnt. Depending upon the choice made, the respective headers are attached to your packet. TCP for example just knows about SYN-ACK, Three-way handshake mechanisms, but does not know the address of the remote-endpoint, or the mechanism of getting the packet across the network.

Congestion control, Flow control help ensure that the network isnt flooded with packets, by regulating the number of packets being sent.

Now, after TCP/UDP header being appended, it moves on to the Network Layer. Till this step, the remote end-points IP address wasnt a part of the packet at all. It is at this step that the Source & Destination IP addresses are added to the packet. This layer actually knows the remote-endpoint.


      Sender                          Receiver


    -----------                      ------------
   |           |   virtual link     |            |
   | Transport | -----------------> | Transport  |
   |           |                    |            |
    -----------                      ------------
         |                                |
         |                                |
    -----------                       -----------
   |           |    virtual link     |           |
   |  Network  | ------------------> |  Network  |
   |           |                     |           |
    -----------                       -----------
         |                                |
         |                                |
    -----------                       -----------
   |           |                     |           |
   | Physical  |                     | Physical  |
   |           |                     |           |
    -----------                       -----------
         ↓                                 ↑
         |____________real link____________|

The senders Transport Layer data, is the exact data received by the receivers transport layer.

As the packet travels down the sender, each layer is adding its own header information, but all of that is removed by the corresponding layer on the receiver.

The advantage is that a virtual link is established, like the one shown above, whereas the real link is only in the physical layer.

Transport layer:

  • Logical communication between processes.

Network layer:

  • Logical communication between hosts.

Transport layer:

  • Responsible for checking that data available in session layer are error free.

Network layer:

  • Responsible for logical addressing and translating logical addresses (ex. amazon.com) into physical addresses (ex. 180.215.206.136)

Transport layer: Protocols used at this layer are :

  • TCP(Transmission Control Protocol)
  • UDP(User Datagram Protocol )
  • SCTP(Stream Control Transmission Protocol)

Network layer: Protocols used at this layer are :

  • IP(Internet Protocol)
  • ICMP(Internet Control Message Protocol)
  • IGMP(Internet Group Message Protocol)
  • RARP(Reverse Address Resolution Protocol)
  • ARP(Address Resolution Protocol)

Transport layer:

  • This layer ensures that the protocols operated at this layer provide reliable end-to-end flow and error control.

Network layer:

  • This layer controls routing of data from source to destination plus the building and dismantling data packets.

osi – Networking: Difference between Transport layer and Networking Layer

Transport: Determines how data is to be sent: Reliably or unreliably. Defines well known services (ports.)

Network: Provides logical addressing, finds best path to a destination.

Leave a Reply

Your email address will not be published.