Transport Layer Problem Sheet - Desklib

Faculty of Science & Technology
Topic 6: Transport layer problem sheet
Q. We can characterise the addressing at the Data Link layer as MAC addresses.
What type of addressing is used at the following layers?
Network: logical addressing is used.
Transport: uses the port address like TCP or UDP.
What entity is being addressed in each case?
Network: Network entity.
Transport: Transport entity.
Q. The data unit (called Protocol Data Unit (PDU)) is called different names at the different layers
of the TCP/IP model.
What are the PDU’s called at each of the following layers?
Data Link: a frame ( or series of bits)
Network Layer: a packet contains the source and destination address.
Transport (TCP): a segment that includes a TCP header
Transport (UDP): a segment that includes data
Physical layer: raw bits transmitted physically via the hardware (1s or 0s)
Q. Describe Multiplexing as it relates to the Transport layer.
Multiplexing in the transport layer is to gather data from the various application processes or
sender, then envelop the data with the header and sending them as a whole to the receiver.
Q. What constitutes a Socket?
How do server sockets and client sockets differ?
A socket is the endpoint in the flow of the communication between the two programs that runs
over a network. The sockets are created and used with a set of requests that are called the
sockets application programming interface.
The server socket is created to blind () to the port and then listen () for the connect () from the
client. The server does not start conversation rather wait for the conversation.
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Faculty of Science & Technology
The client socket is created to connect () to the listen () server. The client socket initiate the
connection.
Q. How many bits are used in a UDP header to store the destination port number?
Explain how you arrived at this number.
The size of the UDP header is 8 to store the destination port number
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