Service Model
What is a socket identifier and what does it consist of?
Socket identifier = IP Address + Port Number
What is TCP segment? What does it consists of?
A fundamental unit of data in TCP protocol.
It consists of header and data payload
What is sliding window (in TCP context)? How does it work?
Flow control mechanism. "Window" slides forward as the receiver acknowledges the data it has received.
What is RTT? How to calculate it?
Round-trip time is the time it takes for a packet to travel from sender to receiver and back as an acknowledgment.
RTT = ACK received - packet send
What are well-known ports (what is the range of ports)?
1-1023 => ports reserved for operation of specific network applications
What is MTU?
Maximum transfer unit is the largest size of packet that can be sent
How delayed acknowledgement works?
It delays the sending of acknowledgment, so that multiple acknowledgments can be sent as a single packet.
What is congestion window?
The congestion window is a TCP state variable that controls the amount of data a sender can transmit into the network before receiving an acknowledgment
What does it mean that TCP buffers data?
TCP buffers data to combine small chunks into larger segments for efficient transmission.
Why is the connection identifier called 5 tuple?
It has 5 elements: protocol name, source host and port, destination host and port
What is silly window syndrome?
It is a situation when data being transmitted is significantly smaller than header overhead.
What is ack clocking?
ack clocking is a mechanism where the sender's data transmission is paced by the arrival of acknowledgments from the receiver. It helps to regulate the flow of packets on the network
What is internet daemon and how does it work?
Internet daemon is a background service that manages network requests for other services. It listens for incoming requests on predefined ports and starts the appropriate service (e.g., FTP, telnet) as needed.
Can you list all 8 flags and their purpose?
Synchronize, Acknowledgment, Finish, Reset, Push, Urgent, Explicit Congestion Notification Echo, and Congestion Window Reduced
What is window probe?
It is a small packet, which "checks" checks the size of the window.
What is selective acknowledgment?
Selective acknowledgment is a feature that allows the receiver to inform the sender about specific blocks of data it has received, even if other parts of the data stream are missing
What organization oversees global IP addresses and well-defined ports?
Internet Assigned Numbers Authority
What is the window size number? What are the legal values for this field?
It tells the sender how much receiver is willing to accept at given time. Legal values are 0-216-1.
How does Nagle's algorithm work?
When TCP buffer is empty, send data immediately. Otherwise, buffer small amounts of data together and wait for ACK of previously sent packet.
How fast retransmission differs from fast recovery?
Fast retransmission triggers an immediate retransmission of a lost packet upon receiving three duplicate ACKs, avoiding a timeout. Fast recovery adjusts the congestion window to allow continued data transmission during recovery, instead of drastically reducing the transmission rate as in slow start.