# Recent questions tagged network-flow

1
Suppose two hosts, A and B, are separated by 20,000 kilometers and are connected by a direct link of R = 2 Mbps. Suppose the propagation speed over the link is $2.5 10^8$meters/sec. How long does it take to send the file, assuming it is sent continuously? Suppose ... send a packet until the preceding one is acknowledged. How long does it take to send the file? Compare the results from (a) and (b).
2
Suppose two hosts, A and B, are separated by 20,000 kilometers and are connected by a direct link of R = 1Gbps. Suppose the propagation speed over the link is $2.5 10^8$ meters/sec Calculate the bandwidth-delay product, $R \times d _{prop}$. Consider sending a file of ... the maximum number of bits that will be in the link at any given time? What is the width (in meters) of a bit in the link?
3
Suppose two hosts, A and B, are separated by 20,000 kilometers and are connected by a direct link of R = 2 Mbps. Suppose the propagation speed over the link is 2.5×1082.5×108 meters/sec. suppose we can modify R. For what value of R is the width of a bit as long as the length of the link?
4
Suppose there is a 10 Mbps microwave link between a geostationary satellite and its base station on Earth. Every minute the satellite takes a digital photo and sends it to the base station. Assume a propagation speed of $2.4 \times 10^8$meters/sec. What is the ... ? Let x denote the size of the photo. What is the minimum value of x for the microwave link to be continuously transmitting?
5
.Suppose two hosts, A and B, are separated by 20,000 kilometers and are connected by a direct link of R = 2 Mbps. Suppose the propagation speed over the link is $2.5 \times 10^8$ meters/sec. Calculate the bandwidth-delay product, $R \times d _{prop}$. Consider ... a general expression for the width of a bit in terms of the propagation speed s, the transmission rate R, and the length of the link m.
6
Suppose N packets arrive simultaneously to a link at which no packets are currently being transmitted or queued. Each packet is of length L and the link has transmission rate R. What is the average queuing delay for the N packets? Now suppose that N such packets arrive to the link every LN/R seconds. What is the average queuing delay of a packet?
7
A packet switch receives a packet and determines the outbound link to which the packet should be forwarded. When the packet arrives, one other packet is halfway done being transmitted on this outbound link and four other packets are waiting to be transmitted. Packets are ... rate is R, x bits of the currently-being-transmitted packet have been transmitted, and n packets are already in the queue?
8
(Common data question P10, P11) P10. Consider a packet of length L which begins at end system A and travels over three links to a destination end system. These three links are connected by two packet switches. Let $d _i, s _i, and R _i$ denote the ... forward packets but instead immediately transmits each bit it receives before waiting for the entire packet to arrive. What is the end-to-end delay?
9
Suppose users share a 3 Mbps link. Also, suppose each user requires 150 kbps when transmitting, but each user transmits only 10 percent of the time. When circuit switching is used, how many users can be supported? For the remainder of this ... are transmitting simultaneously. (Hint: Use the binomial distribution.) Find the probability that there are 21 or more users transmitting simultaneously.
10
This elementary problem begins to explore propagation delay and transmission delay, two central concepts in data networking. Consider two hosts, A and B, connected by a single link of rate R bps. Suppose that the two hosts are separated by m meters, and suppose the propagation speed along the link is ... $d _{prop}$ equals $d _{trans}$.
11
Give a formula for the end-to-end delay of sending one packet of length L over N links of transmission rate R. Generalize this formula for sending P such packets back-to-back over the N links.
12
Visit the Queuing and Loss applet at the companion Web site. What is the maximum emission rate and the minimum transmission rate? With those rates, what is the traffic intensity? Run the applet with these rates and determine how long it takes for packet loss to occur. ... a second time and determine again how long it takes for packet loss to occur. Are the values different? Why or why not?
13
Suppose Host A wants to send a large file to Host B. The path from Host A to Host B has three links, of rates R1 = 500 kbps, R2 = 2 Mbps, and R3 = 1 Mbps. Assuming no other traffic in the network, what is the throughput for the file transfer? Suppose the file is ... throughput, roughly how long will it take to transfer the file to Host B? Repeat (a) and (b), but now with R2 reduced to 100 kbps.
14
How long does it take a packet of length 1,000 bytes to propagate over a link of distance 2,500 km, propagation speed 2.5 · 108 m/s, and transmission rate 2 Mbps? More generally, how long does it take a packet of length L to propagate over a link ... d, propagation speed s, and transmission rate R bps? Does this delay depend on packet length? Does this delay depend on the transmission rate?
15
Suppose that host A is connected to a router R 1, R 1 is connected to another router, R 2, and R 2 is connected to host B. Suppose that a TCP message that contains 900 bytes of data and 20 bytes of TCP header is passed to the IP code at host A for ... of 512 bytes, including an 8-byte frame header, and link R2-B can support a maximum frame size of 512 bytes including a 12-byte frame header
16
Frames arrive randomly at a 100-Mbps channel for transmission. If the channel is busy when a frame arrives, it waits its turn in a queue. Frame length is exponentially distributed with a mean of 10,000 bits/frame. For each of the following frame arrival rates, give the ... frame, including both queueing time and transmission time. (a) 90 frames/sec. (b) 900 frames/sec. (c) 9000 frames/sec.
1 vote
17
Consider a source computer (S) transmitting a file of size $2 * 10^6$ bits to a destination computer (D) over a network of three routers ($R_1$, $R_2$ and $R_3$) and four links $(L_1, L_2, L_3 and L_4)$. $L_1$ connects $S$ to $R_1$; $L_2$ connects $R_1$ to ... the total sum of transmission and propagation delays in transmitting the file from $S$ to $D$? a. 1007 ms b. 1010 ms c. 2010 ms d 2007 ms
18
Suppose that how A is connected to a router R1, R1 is connected to another router R2 and R2 Is connected to how B. Suppose that a TCP message that contains 900 byes of data and 20 bytes of TCP header Is passed to the IP code at host A for delivery to ... of the following Is correct about Total length, OF MF and Fragment offset fields of the header In the last packet transmitted over the link R1-R2
19
You are working on a laptop connected to a $100 \text{Mbps}$ Ethernet LAN. You need a $2 \text{GB}$ file that is on the server in the same LAN. The entire file is also on your pen drive but you have left the pen drive in another room. You ... be able to go and bring the pen drive, before the transfer on the LAN completes. Assume continuous data transmission on the LAN(no packetization required)).
20
21
A geosynchronous satellite has a half-duplex channel with a transmission rate of 10 kbps and a propagation delay of 0.25 sec each way. With a data packet size of 1000 bits and a loss probability p of 0.001 ,(A) what is the expected transmission time of a packet ... all other parameters are the same as part (a), what is the longest channel propagation delay for which we can still use stop-and-wait?
1 vote
22
If two stations A and B uses copper twisted pair cable having capacity 200 bits/sec. if A transmitted 20 frames to B each of size 50 bits, Assume RTT is neglected. What is the time (in Sec) required to transmit the single frame from A to B if pipelining has been used?
23
Suppose that x bits of user data are to be transmitted over K-hop path in a packet-switched network as a series of packets each containing p data bits and h header bits with x>>(p+h). The bit rate of lines is b bps and propagation delay is negligible. What is the time taken by ... to transmit total bits? (p+h) x/b bits (p+h) x/pb bits p x/b bits hx/pb bits Please tell the answer with explanation.