Questions tagged [computer-networks]
Questions about problems that arise when you connect multiple computers to form a network.
239
questions
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Bit stuffing in ethernet
I am naive to computer networks. I studied bit stuffing protocol which helps in identifying the end of the frame. If we assume a two systems which use ethernet protocol at data link layer. How the end ...
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8 views
Why not use a timer at sender instead of increasing transmision time in CSMA/CD to detect collisions?
In CSMA/CD protocol in order to detect collision Transmission time should be at least equal to two times 2×Tp, that means we have to change the frame size accordingly. Instead of all this why can't ...
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1answer
15 views
Calculate minimum and maximum Ethernet (IEEE 802.3) frame size from frame format
According the frame format of Ethernet
Minimum Frame Size should be :
7Bytes + 1Bytes + 6Bytes + 6Bytes + 2Bytes + 46Bytes +4Bytes = 72Bytes
Maximum Frame Size ...
0
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1answer
42 views
All-zeros subnet and All-ones subnet
It is said that practically all-zeros and all-ones subnets are not used.
Let us consider an a network $200.200.13.13/25$
Here Network ID is represented by using $25$ bits and Host ID using $32-25=7$ ...
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1answer
20 views
Hamming code distance and error detection
Suppose that data are transmitted in blocks of sizes 1000 bits. What is the maximum
error rate under which error detection and retransmission mechanism (1 parity bit per
block) is better than using ...
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1answer
19 views
IP addresses and CIDR suffixes
I'm somewhat confused about IP addresses and subnet masks.
Can a same IPv4 address have two different CIDR suffixes ?
for example 95.100.252.115/28 and 95.100.252.115/26 ?
If not, how is the CIDR ...
1
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1answer
50 views
Basic Question in networking - why max data size of ip datagram 65535 BYTES and not 65535 bits?
I recently started computer networks with some understanding of algorithms and discrete mathematics. I am completely new. Kindly elaborate following -
data size of ip datagram = 16bits. So with this $...
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29 views
Computing effective transfer speed [Effective Transmission rate?]
A) Given 10 Mb/s network through three store-and-forward switches with frame size of 5000 bits and length of ACK frames of ...
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0answers
37 views
Construction of Omega Network
I understand that we could draw N * N Omega Network,
But can we draw an Omega Network to connect 6 CPUs to 4 memories? (The number of CPUs does not equal the number of memories)
2
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1answer
27 views
Confused between bandwidth and frequency
I am new to Computer Science and started learning about computer networking very recently. I know that bandwidth means how many bits can be sent through the channel in 1 second. However, recently I ...
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0answers
15 views
Why should a potential drawback of layering be that functionality at one layer may need information that is present only in another layer?
Protocol layering has conceptual and structural advantages [RFC 3439]. As we have seen, layering provides a structured way to discuss system components. Modularity makes it easier to update system ...
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7 views
maximal number of time slots until a successful transmission in adaptive tree walking protocol
i have a problem understanding some vital points in adaptive tree walking protocol:
for simplicity sake, only two stations want to broadcast in the given network: A and C.
what is the maximal number ...
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1answer
26 views
Finding maximal and average number of time slots in an Adaptive tree walk protocol
Tried to research here and on other sites with no luck regarding finding the maximal and average number of time slots in an Adaptive tree walk protocol. i'll explain what i mean here:
In a simple(...
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0answers
37 views
utilization of bitmap protocol
I am curious about utilization calculation in the bitmap protocol. especially if there's a difference between if only station 0 wants to broadcast(and the others doesn't) or only some other station ...
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0answers
9 views
minimal broadcasting frame length in a CSMA/CD protocol
i'm unsure about the following question, would appreciate your assistance with it:
in a CSMA/CD network with a cable length of L, and propagation speed T, with no need of repeaters(the signal is not ...
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0answers
9 views
theoretical question about difference between transmitting stations in Bit-Map Protocol
i am wondering about the difference between the transmitting station in a bit map protocol.
for instance, if we have 8 broadcasting stations numbered 0-7, and the racing (contenting) time is $t_0$ ...
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0answers
24 views
Affects of altering a line in “stop and wait” protocol(no noises)
what will happen if we change "to_physical_layer(&s)" to "to_physical_layer(&r)" in the following code(marked in the code where)?
does it make the protocol fail? if so, show a scenario it ...
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0answers
19 views
go back n protocol scenario consequences
i am not sure with tihs question. i will post it here along with my attempt:
the following scenario is regarding go back protocol n, with 3 bits for sequential numbering, assuming that the following ...
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0answers
55 views
finding the overhead and distance of an unknown code based on message making algorithm
for an information word M with m bits that is coded as following:
M is coded into a word A using an unknown code that allows detection of not more than one error.
the code word is the word obtained ...
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0answers
31 views
Calculating p-persistent CSMA Network probability
Let's say that, in a p-persistant CSMA network one station, X, is ready to transmit data. All other stations are idle for 5 time slots after X has become ready. What is the probability that X ...
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15 views
Finding current levels when encoding information in a channel
I am stuck with the following question:
In a noised channel with a bandwidth of 4 kHz that has the signal-noise ratio of 30 decibels, if it is known that the maximal broadcasting speed is 16000 bps,...
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0answers
14 views
Maximal number of parallel cellular calls with no adjacent cells in a hexagonal setting
Is it possible to find an optimization to the following theoretical case?
Given is a cellular (phone) system with hexagonal cells, where the volume of transmission and the size of the cells are ...
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0answers
22 views
A file is sent from host A to client B, the packet passes through router R on its way to B. Calculate the total delay for the file to reach B
This is a question from an old exam that ive been trying to work out:
The 40000 bit file is split into 10 packets with a 400 bit header added to each packet
The link from A to R is 500 km long and ...
2
votes
1answer
67 views
Network throughput with random delay selected from uniform distribution
Background:
I am working with IoT devices which broadcast status messages over a wireless channel periodically and at a rather high rate (500-5000 Hz). Receiving every message is not crucial but the ...
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0answers
11 views
Networks-on-Chip : separable allocator VS wavefront allocator
How is separable allocator different from wavefront allocator ?
See page 86 and 87 of On-Chip Networks, Second Edition Synthesis Lectures on Computer Architecture
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Application deployement and network models [closed]
I am a self-taught in computer science. I am interested on have a robust test book on which study the nut and bolt of application deployment.
I mean all the processes involved in getting new software ...
0
votes
1answer
15 views
Maximum number of nodes connected when the link has a large buffer
A link of capacity 100 Mbps is carrying traffic from a number of sources. Each source generates an on-off traffic stream;when the source is on, the rate of traffic is 10 Mbps, and when the source is ...
0
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1answer
23 views
What is the name of the domain or theoretical problem of transmitting game states in an online game
For example, in chess (or any online game), you broadcast the game state to other players at certain times (every n-milliseconds or after a move is made). Thereupon, a player's game client renders the ...
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16 views
transmit delay end to end
If PC1 divided the original packet (1.5 MB) to three equal packets (each packet is the length of 512
KB), then how much time is needed to transmit the 3 packets back-to-back.
how can i solve this ...
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0answers
114 views
Efficiency of UDP protocol
When 54 bytes of data is transferred using the UDP protocol, the efficiency is? (In per cent)
IN UDP, the maximum datagram size can be $2^{16}-1 \, bytes$
Now to this, 8 Bytes of UDP header is ...
0
votes
1answer
43 views
Why does packet delivery time only count transmission time once?
Why is packet delivery time equal to transmission time + propagation delay, and not equal to 2*(transmission time) + propagation delay?
At the end of packet delivery time, doesn't that mean that ...
0
votes
2answers
56 views
How to decide which bytes will form a packet ?(computer networks)
In wireless communication , I understand what it means to transmit a "bit" but I wanted to understand what exactly does it mean by a packet .
*******POST EDIT/RECEIVING INITIAL ANSWERS*******
I got ...
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0answers
25 views
Stop and Wait Efficiency
A sender uses Stop and Wait protocol for transmission of 8000K bits size frames on a 1Gbps satellite channel with a propagation delay of $400ms$.What will be the link utilization(in percent),if ...
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45 views
Computer Networks, bandwidth calculation
I don't know if this is the right place to ask this kind of questions, but I'm a little desperate and I can't find the answer to this Computer Networks exam question.
"A point to point 1000 km ...
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46 views
Understanding acknowledgement mechanism in sliding window protocol
I came across following problem:
Node A sends packets to B through router R. The link A-R is instantaneous , but the R->B link transmits only 1 packet each second , one at a time . Assume A sends ...
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1answer
47 views
What are the things one can do with the internet without the World Wide Web? [closed]
If the question above makes any sense!
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0answers
158 views
Exercise: Sliding window protocol: Bits for sequence number
This is a task in a lecture on computer networks:
"Suppose you are designing a sliding window protocol for a 1-Mbps point-to-point link to the moon, which has a one-way latency of 1.25 seconds. ...
3
votes
1answer
81 views
Private IP and public IP
What we see on our devices is essentially the private IP given to us by the ISP; thereby, whenever we access the internet, this private IP is first converted to public IP (by ISP through NAT), ...
0
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1answer
69 views
Wifi throughput calculation
I have a problem which i don't know how to calculate or more specifically what am I missing. The subject is about 802.11 (wifi)
The selected PHY rate is 54Mbit/s, that is whenever DATA is being sent ...
0
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1answer
41 views
The role of the root switch after Spanning Tree Protocol has established a tree network in a LAN?
In Spanning Tree Protocol, a root switch is selected at first, and then somehow, the shortest path from each other switch to the root is obtained. Thus we established a tree network.
My questions ...
0
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1answer
431 views
What exactly is transmission time?
Seems very trivial but I'm confused which one of these correctly define transmission time.
Time taken by a message to reach receiver.
Time taken to push message on the link by the sender.
Which ...
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1answer
83 views
Stop and Wait retransmission of packets?
In a communication link out of p packets one packet will be lost. If stop and wait protocol is used then expected number of retransmissions for a packet?
(A) P/(1-P)
(B) P
(C) 1/(1-P)
(D) 1/P
I ...
0
votes
1answer
284 views
The min number of distinct sequence numbers required to ensure correct operation of the ARQ scheme is
In a sliding window ARQ scheme, the transmitter's window size is N and the receiver's window size is M. The minimum number of distinct sequence numbers required to ensure correct operation of the ARQ ...
3
votes
1answer
55 views
Anonymous Visibility Check in P2P networks
I'm working on a problem for a P2P network for games. The problem is the following:
Consider two opponents on a grid, each stores it's own position.
Player 1 wants to know if it sees player 2. In ...
0
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1answer
41 views
why not just one header in TCP/IP?
I was reading through the computer network fundamentals. I noticed that there are headers added at each layer in the OSI model. However, can we not have just one header above the App layer that ...
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votes
2answers
29 views
When packets are not full?
When in computer networks it happens that the packets are not full? I have heard that sometimes in UDP that happens, if that’s the case, why not all the space is not used?
0
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1answer
73 views
Paxos Consensus
how does Paxos Consensus algorithm behave in an asynchronous environment? Because as far as I know Paxos only work in synchronous environment. Correct me if I am wrong :)
Sorry for the noob question,...
2
votes
1answer
67 views
How can average queuing delay exceed 1 if the $La/R \leq 1$?
Consider a router with a packet arrival rate of $a$ where each packet has $L$ bits, and a transmission rate (in bits/s) of $R$. My textbook describes the traffic intensity as $\frac{La}{R}$ and states ...
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137 views
What will happen if congestion window size touches to zero in congestion control mechanisms in TCP?
Folowing is the Congestion Control Window graph of TCP. What will happen if Congestion Window reaches to zero when timeout occurs ?
0
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1answer
19 views
Is it possible to give a guarantee about the accuracy of the local time?
Assuming there is no attack/bug and I use NTP: Are there any formal guarantees about the accuracy of the local time? Can there be any over the network?
Even if the communication is going directly ...
