TCP/IP layer
¡ Describe TCP and its functions
¡ Describe TCP synchronization and flow control
¡ Describe UDP operation and processes
¡ Identify common port numbers
¡ Describe multiple conversations between hosts
¡ Identify ports used for services and clients
¡ Describe port numbering and well known ports
¡ Understand the differences and the relationship between MAC addresses, IP addresses, and port numbers
TCP Operation
¡ How the transport layer provides reliability and flow control?
¡ By sliding windows and sequencing numbers along with a synchronization process.
¡ TCP is a connection-oriented protocol.
¡ So before transmission, the two hosts go through a synchronization process to establish a virtual connection.
Windowing and window size
¡ Windowing is a process of flow control.
¡ Window size determines the amount of data that can be transmitted at one time before the destination responds with an acknowledgment.
¡ Window-sized is in number of bytes.
¡ If the window size is 1, each byte must be acknowledged before the next byte is sent.
Sequence number
¡ sequence numbers are transmitted so that the receiver can reassemble the bytes in their original order.
¡ also act as reference numbers so that the receiver will know if it has received all of the data.
¡ TCP uses positive acknowledgment and retransmission (PAR) to control data flow and confirm data delivery.
¡ With PAR, the source sends a packet, starts a timer, and waits for an acknowledgment before it sends the next packet in the session.
¡ If the timer expires before the source receives an acknowledgment, the source retransmits the packet and resets the timer. (window size is reduced)
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