Questions tagged [computer-networks]
Questions about problems that arise when you connect multiple computers to form a network.
255
questions
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11 views
Putty access denied [closed]
I installed putty in Windows 10 and in kali linux I have run the ssh service, but when i try to access remote login using the root and password it is showing as access denied. I also went to ...
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14 views
Count to infinity problem (routing) between unsynchronized stations(tricky)
i was wondering, will count to infinity can occur in the following cases? if so, will it necessarily occur or can the routing tables stabilize themselves?
Distances:
From A to B - 3
from B to C - 4
...
1
vote
1answer
22 views
S/Kademlia dynamic crypto puzzle
In S/Kademlia two crypto puzzles is used, one static and dynamic. The static is used to generate a key pair that makes an eclipse attack difficult to achieve, the dynamic to make Sybil attacks harder. ...
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0answers
17 views
IGMP Multicasting
The definition about IGMP on the internet goes like this-->
The Internet Group Management Protocol (IGMP) is a communications
protocol used by hosts and adjacent routers on IPv4 networks to
...
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0answers
9 views
distance of a code name in scheme
i wonder: is it true that if we take a information word, call it M(with m bits) for example, and code it by first coding M using a code, that we don't know anything about, except of it a length of k, ...
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25 views
Expected number of retransmissions for a packet
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
...
0
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1answer
45 views
Probability of detecting errors in codewords
I have been struggling with the below question for quite some time, and I don't have a pointer to move forward.
A certain Error Control Coding scheme using block codes takes an input block (...
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27 views
Stop and Wait protocol in a half duplex scheme
glad i found this site. would appreciate help with this: in picture i uploaded there's a state diagram of a "stop and wait" protocol in a half duplex channel. we assume current status is (10A).
...
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0answers
10 views
P2p versus Client Server Architecture: Performance
I want to understand the difference between P2P and Client server Architecture in the context of Performance. Book has drawn a graph. The link of the book is:
Computer Networking: A top-down ...
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0answers
19 views
TCP congestion control problem
Suppose that the maximum transmit window size for a TCP connection is 12000 bytes. Each packet consists of 2000 bytes. At some point in time, the connection is in slow-start phase with a current ...
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0answers
17 views
fragmentation in ipv4 is done at source or routers or at both
fragmentation in ipv4 is done at source or routers? according to what i read, fragmentation can be avoided at source, by doing segmentation at transport layer wisely to match MTU of source network... ...
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3answers
93 views
Is the constant pi (not Raspberry) ever used in general computer science?
Is the constant pi (not Raspberry) ever used in general computer science? If so, how so or when is it applicable?
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54 views
Are acknowledgements used in CSMA/CD?
To provide context, I have read that CSMA/CD does not rely on acknowledgements and relies on collision signals to check for successful or unsuccessful transmissions (from what was explained in the ...
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1answer
28 views
Is there a way to access hard drives while computer sleeps?
Is there any way at all possible or possible with hardware (aside from a NAS) to access hard drives while the computer is in a low power mode such as sleep (aside from WOL)?
For example, can I log ...
0
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1answer
44 views
Diffie-Hellman and its disadvantage with large primes
I was reading our university slide on the Diffie-Hellman where it is mentioned that one of the disadvantages of D-H is that For large prime, $p-1$ is an even number so, $\mathbb{Z}^*_p$ will have a ...
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0answers
12 views
Given two or more nodes in a network, is it possible to determine the one-way link latencies between two nodes that share a bi-directional connection?
We already know that detecting the one-way latency between only two nodes is impossible.
However, if I have a number of nodes in the same subnet that all know about each other, can measure round-trip ...
2
votes
1answer
72 views
Two Generals Problems - What's wrong with my approach?
Some time ago, I've come across the Two Generals Problem and that it cannot be resolved. Now, recently, I've had an idea how to approach it. IMHO, it is a very obvious way to handle it but I haven't ...
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28 views
Calculation of total delay for multiple packets and multiple hops
I had this question on my homework for a class and don't understand the solution at all.
Assume there is no direct link between A and B. There exists one router C and two hops: Link A-C and link C-B....
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21 views
How TDM(TIme division multiplexing) affects bandwidth of the link and bandwidth of each station?
Sir
I have recently started studying computer networks. I have following doubt. Please clarify.
In TDM(Time division multiplexing), say we have broadcast link and N stations are connected to it. Then ...
0
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1answer
23 views
How can I download a streaming file without the file's specific address? [closed]
I want to download a streaming file, but I don't know the real address of that file, only the address where the stream is.
How can I download that file? Is it possible to know the address of the file ...
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0answers
8 views
What is the average time for a node to transmit on the shared medium for Ethernet? (IEEE 802.3)
Suppose a shared ethernet link L, in which for nodes T1-T4 and a router R are connected:
...
2
votes
2answers
788 views
How do web browsers find out the MAC address?
While reading through my textbook, I discovered that if you want to access a particular web page, your web browser will find out the IP address of the web server that hosts the web page and try and ...
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0answers
56 views
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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0answers
11 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 ...
0
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1answer
117 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
89 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 $32-25=7$ ...
0
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1answer
83 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 ...
0
votes
1answer
27 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
vote
1answer
86 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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0answers
42 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 ...
0
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0answers
48 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
votes
1answer
35 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
24 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 ...
1
vote
1answer
76 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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67 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
11 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
25 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
22 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
57 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 ...
0
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0answers
74 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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0answers
16 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
15 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
85 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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27 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
16 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 ...
