# Recent questions tagged lan-technologies 1 vote
4 answers
1
Suppose there are $n$ stations in a slotted $LAN$. Each station attempts to transmit with a probability $P$ in each time slot. The probability that only one station transmits in a given slot is $nP(1-P)^{n-1}$ $nP$ $P(1-P)^{n-1}$ $n^{P}(1-P)^{n-1}$
0 votes
2 answers
2
Suppose that an 11-Mbps 802.11b LAN is transmitting 64-byte frames back-to-back over a radio channel with a bit error rate of 10−7. How many frames per second will be damaged on average?
0 votes
1 answer
3
How many frames per second can gigabit Ethernet handle? Think carefully and take into account all the relevant cases. Hint: the fact that it is gigabit Ethernet matters.
1 vote
0 answers
4
Some books quote the maximum size of an Ethernet frame as 1522 bytes instead of 1500 bytes. Are they wrong? Explain your answer.
0 votes
0 answers
5
Ethernet frames must be at least 64 bytes long to ensure that the transmitter is still going in the event of a collision at the far end of the cable. Fast Ethernet has the same 64-byte minimum frame size but can get the bits out ten times faster. How is it possible to maintain the same minimum frame size?
0 votes
1 answer
6
Consider five wireless stations, A, B, C, D, and E. Station A can communicate with all other stations. B can communicate with A, C and E. C can communicate with A, B and D. D can communicate with A, C and E. E can communicate A, D and B. (a) When ... possible? (b) When B is sending to A, what other communications are possible? (c) When B is sending to C, what other communications are possible?
0 votes
1 answer
7
How long does a station, s, have to wait in the worst case before it can start transmitting its frame over a LAN that uses the basic bit-map protocol?
1 vote
2 answers
8
What is the length of a contention slot in CSMA/CD for (a) a 2-km twin-lead cable (signal propagation speed is 82% of the signal propagation speed in vacuum)?, and (b) a 40-km multimode fiber optic cable (signal propagation speed is 65% of the signal propagation speed in vacuum)?
0 votes
0 answers
9
In an infinite-population slotted ALOHA system, the mean number of slots a station waits between a collision and a retransmission is 4. Plot the delay versus throughput curve for this system.
0 votes
1 answer
10
A large population of ALOHA users manages to generate 50 requests/sec, including both originals and retransmissions. Time is slotted in units of 40 msec. (a) What is the chance of success on the first attempt? (b) What is the probability of exactly k collisions and then a success? (c) What is the expected number of transmission attempts needed?
0 votes
1 answer
11
A group of N stations share a 56-kbps pure ALOHA channel. Each station outputs a 1000-bit frame on average once every 100 sec, even if the previous one has not yet been sent (e.g., the stations can buffer outgoing frames). What is the maximum value of N?
19 votes
6 answers
12
Consider that $15$ machines need to be connected in a LAN using $8$-port Ethernet switches. Assume that these switches do not have any separate uplink ports. The minimum number of switches needed is ______
1 vote
1 answer
13
Consider a scnario of CSMA/CD network. Suppose A & B attempt to transmit a frame simultaneously and collide. Using exponential backoff algorithm A chooses K=0 and B chooses K=1. Again they collide and after the 2nd collision both A & B will choose K with equal probability from set: For A {0,1} and for B {0,1} For ... for B {0,1} For A {0,1} and for B {0,1,2,3} For A {0,1,2,3} and for B {0,1,2,3}
0 votes
1 answer
14
If probability of frame reaching safely is 0.1 then mean number of transmissions of a frame to make it success is _____. what is wrong with the approach given below random variable x is the number of transmission' X 1 2 3 4 so on P(X) 0.1 0.9*0.1 0.9*0.9*0.1 0.9*0.9 ... variable E[X]= $\sum X*P(X)$ which comes out to be 100. but given the answer is 10 using 1/p. (what is wrong in above aproach?)
1 vote
0 answers
15
As per the explanation here https://gateoverflow.in/1983/gate2014-2-25#7752 the answer should be 21. But 17 is provided as answer.
0 votes
2 answers
16
Let cluster of stations share 48kbps of pure aloha channel. Every station outputs frame of length 1024 bit in every 50 seconds. Then what is the maximum value of number of stations?
0 votes
1 answer
17
0 votes
0 answers
18
The minimum frame length (in bytes) of the cable of length 240 meter for transmitting data at a rate of 500 Kbps in IEEE 802.3 LAN is __________. (Assume the signal speed in the cable to be, 2,00,000 m/s)
4 votes
2 answers
19
Here i'm not able to get after how much time X and Y will face first collision
4 votes
0 answers
20
5 votes
3 answers
21
Consider two nodes A and B on the same Ethernet, and suppose the propagation delay b/w the two nodes is 225-bit times. Suppose at the time both nodes A and B begin to transmit a frame.Both nodes transmit a 50-bit jam signal after detecting collision. For 10^7 bit/set find the time at which both nodes A and B sense idle channel?
1 vote
1 answer
22
3 votes
2 answers
23
What is the maximum theoretical percent utilization in a 802.3 LAN (that uses 10 base 5 cable) with 128 stations connected to five 500 meter segments. The data rate is 10 Mbps. Assume the frame size is 256 bytes and standard slot time is 51.2 μsec. (A) 70% (B) 90% (C) 80% (D) 60%
1 vote
2 answers
24
The baud rate is Always equal to the bit transfer rate Equal to twice the bandwidth of an ideal channel Not equal to the signalling rate Equal to half of the bandwidth of an ideal channel
4 votes
2 answers
25
A broadcast channel has 10 nodes and total capacity of 10 Mbps. It uses polling for medium access. Once a node finishes transmission, there is a polling delay of 80 &mu;s to poll the next node. Whenever a node is polled, it is allowed to transmit a maximum of 1000 bytes. The maximum throughput of the broadcast channel is A) 1 Mbps B) 100/11 Mbps C) 10 Mbps D) 100 Mbps please explain
6 votes
2 answers
26
On a LAN ,where are IP datagrams transported? In the LAN header In the application field In the information field of the LAN frame After the TCP header
27 votes
5 answers
27
Which of the following statements is FALSE regarding a bridge? Bridge is a layer $2$ device Bridge reduces collision domain Bridge is used to connect two or more LAN segments Bridge reduces broadcast domain
4 votes
4 answers
28
Consider a 10 Mbps token ring LAN with a ring latency of 400 µs. A host that needs to transmit seizes the token. Then it sends a frame of 1000 bytes, removes the frame after it has circulated all around the ring, and finally releases the token. This process is repeated for every frame. Assuming that only a single host wishes to transmit, the effective data rate is 1 Mbps 2 Mbps 5 Mbps 6 Mbps