4 Replies to “Understanding OSI

  1. I am confused so the transport takes care of the transport using udp or tcp protocol. With the example of port 80 it knows it needs to go thru the webserver. It adds a header

    The network makes sure it know it route by adding an source and destination ip. Adds it as a header

    Together they make sure the data is send to the right location?

    The data link makes sure it is in the right lan segment adding another header and a trailer correcting errors?
    Because it may hop from router to router the mac adress can change but the ip stays the same?

    Is this correct i know there is more to it. But i typed only the parts that i wanted to make sure was correct.

    Also in the quiz question 2
    Transport is linked to delivering data error free.
    Is it because of the protocols transport uses?
    I thought that in data link it would correct errors?

    1. What you’ve said is correct. Each layer (2-4) add their own headers, and they each have a specific job to do.
      Layer 2 gets the frame delivered from hop to hop
      Layer 3 gets the packet delivered to the right network, and the right host
      Layer 4 gets the segment delivered to the right application

      At layer 2, errors can be detected, causing bad frames to be dropped
      At layer 4, if TCP is used, the receiver can request that the sender resend the missing data

      Does that help?

Leave a Reply