GATE CS Transport Layer: Flow Control, Congestion Control, UDP, TCP, Sockets questions

With respect to a TCP connection between a client and a server, which one of the following statements is true?

A TCP sender successfully establishes a connection with a TCP receiver and starts the transmission of segments. The TCP congestion control mechanism's slow-start threshold is set to $10000$ segments. Assume that the round-trip time is fixed at $1$ millisecond. Assume that the sender always has data to send, the segments are numbered from $1$, and no …

Consider the implementation of sliding window protocol over a lossless link, with a window size of $W$ frames, where each frame is of size $1000$ bits (including header). The bandwidth of the link is $100 \mathrm{kbps}\left(1 \mathrm{k}=10^{3}\right)$ and the one-way propagation delay is $100$ milliseconds. Assume that processing times at the sender …

Consider a new TCP connection between a sender and a receiver. The receiver advertised window is constant at $48$ KB, the maximum segment size (MSS) is $2$ KB, and the slow start threshold for TCP congestion control is $16$ KB. Assume that there are no timeouts or duplicate acknowledgements. The number of rounds of transmission required for the …

Consider the $3$-way handshaking protocol for TCP connection establishment. Let the three packets exchanged during the connection establishment be denoted as $\text{P1, P2}$, and $\text{P3}$, in order. Which of the following option(s) is/are TRUE with respect to TCP header flags that are set in the packets?

​​​​​Consider the following statements: Address Resolution Protocol (ARP) provides a mapping from an IP address to the corresponding hardware (link-layer) address. A single TCP segment from a sender $S$ to a receiver $R$ cannot carry both data from $S$ to $R$ and acknowledgement for a segment from $R$ to $S$ Which one of the following is CORRECT?

​​​​Suppose we are transmitting frames between two nodes using Stop-and-Wait protocol. The frame size is $3000$ bits. The transmission rate of the channel is $2000$ bps (bits/second) and the propagation delay between the two nodes is $100$ milliseconds. Assume that the processing times at the source and destination are negligible. Also, assume that the …

​$\mathrm{TCP}$ client $\mathrm{P}$ successfully establishes a connection to $\text{TCP}$ server $\mathrm{Q}$. Let $\text{N}_{P}$ denote the sequence number in the $\text{SYN}$ sent from $\mathrm{P}$ to $\mathrm{Q}$. Let $\text{N}_{Q}$ denote the acknowledgement number in the SYN ACK from $\text{Q}$ to $\text{P}$. Which of the following …

Consider a $\text{TCP}$ connection operating at a point of time with the congestion window of size $12$ $\text{MSS}$ (Maximum Segment Size), when a timeout occurs due to packet loss. Assuming that all the segments transmitted in the next two $\text{RTTs}$ (Round Trip Time) are acknowledged correctly, the congestion window size (in $MSS$) during the …

Suppose two hosts are connected by a point-to-point link and they are configured to use $\textsf{Stop-and-Wait}$ protocol for reliable data transfer. Identify in which one of the following scenarios, the utilization of the link is the lowest.

Suppose you are asked to design a new reliable byte-stream transport protocol like $\text{TCP}.$ This protocol, named $\textsf{myTCP}$, runs over a $100 \mathrm{~Mbps}$ network with Round Trip Time of $150$ milliseconds and the maximum segment lifetime of $2$ minutes. Which of the following is/are valid lengths of the Sequence Number field in the …

Consider a $100 \; \text{Mbps}$ link between an earth station (sender) and a satellite (receiver) at an altitude of $2100 \; \text{km}.$ The signal propagates at a speed of $3 \times 10^{8} \; \text{m/s.}$ The time taken $\text{(in milliseconds,} \; \textit{rounded off to two decimal places})$ for the receiver to completely receive a packet of …

Consider the data transfer using $\text{TCP}$ over a $1 \; \text{Gbps}$ link. Assuming that the maximum segment lifetime $\text{(MSL)}$ is set to $60 \; \text{seconds},$ the minimum number of bits required for the sequence number field of the $\text{TCP}$ header, to prevent the sequence number space from wrapping around during the $\text{MSL}$ is …

A $\text{TCP}$ server application is programmed to listen on port number $P$ on host $S$. A $\text{TCP}$ client is connected to the $\text{TCP}$ server over the network. Consider that while the $\text{TCP}$ connection was active, the server machine $S$ crashed and rebooted. Assume that the client does not use the $\text{TCP}$ keepalive timer. …

Consider two hosts $P$ and $Q$ connected through a router $R$. The maximum transfer unit $\text{(MTU)}$ value of the link between $P$ and $R$ is $1500$ bytes, and between $R$ and $Q$ is $820$ bytes. A $\text{TCP}$ segment of size $1400$ bytes was transferred from $P$ to $Q$ through $R$, with $\text{IP}$ identification value as …

Consider the sliding window flow-control protocol operating between a sender and a receiver over a full-duplex error-free link. Assume the following: The time taken for processing the data frame by the receiver is negligible. The time taken for processing the acknowledgement frame by the sender is negligible. The sender has infinite number of frames …

Consider the three-way handshake mechanism followed during $\text{TCP}$ connection establishment between hosts $P$ and $Q$. Let $X$ and $Y$ be two random $32$-bit starting sequence numbers chosen by $P$ and $Q$ respectively. Suppose $P$ sends a $\text{TCP}$ connection request message to $Q$ with a $\text{TCP}$ segment having …

Consider a $\textsf{TCP}$ connection between a client and a server with the following specifications; the round trip time is $6$ ms, the size of the receiver advertised window is $50$ KB, slow-start threshold at the client is $32$ KB, and the maximum segment size is $2$ KB. The connection is established at time $t=0$. Assume that there are no …

Consider a long-lived $\text{TCP}$ session with an end-to-end bandwidth of $1\; \text{Gbps}\; (=10^9$ bits-per-second$).$ The session starts with a sequence number of $1234$. The minimum time (in seconds, rounded to the closet integer) before this sequence number can be used again is _________.

Consider the following statements regarding the slow start phase of the TCP congestion control algorithm. Note that cwnd stands for the TCP congestion window and MSS window denotes the Maximum Segments Size: The cwnd increases by $2$ MSS on every successful acknowledgment The cwnd approximately doubles on every successful acknowledgment The cwnd increases …