Questions about problems that arise when you connect multiple computers to form a network.

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Slotted ALOHA and FDMA

I have this exercise: A network is composed of 19 nodes: 9 peripheral sensors $P_1, ..,P_9$, 9 repeaters $R_1,..,R_9$ and a central station $C$. The system works on a band of $3MHz$ centered at $f_0 ...
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1answer
43 views

What makes Internet of Things (IoT) environment different from other environments?

What makes IoT environment different from other environments (e.g., cloud, pervasive, web)? In general, the latter are components of the IoT environment, but what are the specific properties of IoT?
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1answer
33 views

Difference between 2f+1, 2f and 3f+1

I am currently reading the Practical Byzantine Fault Tolerance paper. I am unable to completely understand the difference between 2f and ...
4
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1answer
64 views

How internet speed is manipulated at the physical level

Although I am a computer science major, I am having a hard time understanding how internet providers have control over internet speed (example: offer different speeds to different customers, one with ...
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1answer
34 views

client and server programs [closed]

I\’m a novice programmer that\’s learning how to program on his own currently. I\’m currently fiddling around with a server/client program that allows me to send a signal from one computer to another. ...
0
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1answer
12 views

In the Data Link Layer, is it better to use large or small frames?

I understand how the layer works to an extent, but cannot seem to figure out if the data link handles big frames more efficiently due to error detection or small frames better. I am assuming from my ...
0
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1answer
19 views

Class C can have _______ 1s with the remaining bits 0s [closed]

A subnet mask in class C can have _______ 1s with the remaining bits 0s. MyApproach: Class C subnet is 255.255.255.0.So, accordingly it has 9 1s on first byte,9 1s on second byte and 9 1s on ...
2
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1answer
32 views

How does the Weibull distribution work as fault model in wireless sensor networks?

I am a little bit confused with the concept of using the Weibull distribution or other distribution for fault model. As I understand, in simulation this distribution is often used for modelling a ...
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1answer
27 views

How does MAC layer back-off work?

How does it help avoid frame collisions? Are there any rules for when the back off is allowed, especially in the case of wireless networks?
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1answer
45 views

How would I add 0.0.15.255. to 172.1.6.255.? [closed]

How would I add 0.0.15.255 to 172.1.6.255, talking about IPv4 networks here. I have done things like 192.168.1.15 plus 0.0.1.30 to be 192.168.2.45. but when it goes over the limit of 255, I just do ...
4
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1answer
29 views

How can I calculate optimal batch sizes for calls to an external server?

So I have a large number of commands, say 500,000, that I want to send and run on a server somewhere else, and get the answers back. All of these commands together takes a long time to execute - ...
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1answer
43 views

Why can't you see computer behind a router?

I understand the basics of networking(DNS,DHCP,IP,MAC, etc.). I have installed a router and plugged my computer into the router. On the other end of the router the cable goes somewhere to a switch(I ...
0
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2answers
29 views

Is it possible to calculate the propagation delay if only the length of the link is known & not the speed at which a bit travels into the link?

Consider a $10^7$ bps link that is $400$ km long, with a queue large enough to hold $2000$ packets.Assume that the packets arrive at the queue with an average rate of $4000$ packets per second ...
2
votes
1answer
34 views

Why arrival process of packets at a switch is not a Poisson Process?

"Packet arrivals are not Poisson .... but some events are, such as web requests and new flow arrivals" I know since the network traffic is very bursty, they are not Poisson. But I am unable to ...
2
votes
1answer
36 views

Term for shifting work to idle machines

I am looking for a term here. A while ago, i was told about a network in which all the computers are connected in parallel, and when a computer is idle, the central server sends heavy cpu usage tasks ...
0
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0answers
23 views

Counting hops in a network when broadcasting

Given the below network, how many hops are required to broadcast a message from one router to all others using: a. reverse-path forwarding b. a sink tree for the source router c. sequence number ...
2
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0answers
14 views

Benes (Fat Tree) Network for number of inputs/outputs that is not 2^n

I was reading about Benes Network construction in this book. Their construction is easy for a number of inputs and outputs that is an exponent of two. However it seems to me that for a number of i/o ...
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1answer
28 views

Do iterative DNS queries return results from the servers cache?

So if i only used iterative requests to a recursive dns server and since this server has cached results from recursive queries, does this mean the iterative request gets a result from the cache or ...
0
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1answer
49 views

What this subnetting restriction means

I was reading Data Communication book by Forouzan in which there is a one restriction put on CIDR subnetting by Internet authorities: First IP address in the block should be evenly divisible by ...
3
votes
1answer
52 views

Algorithm for executing a command against a million hosts

Consider the following problem: you are given a set of one million machines (hosts), and you would like to have the ability to execute at will an arbitrary command against the whole set; for the ...
38
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4answers
3k views

Why are so many internet protocols text-based?

From what I have found, a very large amount of protocols that travel over the internet are "text-based" rather than binary. The protocols in question include, but are not limited to HTTP, SMTP, FTP (I ...
2
votes
2answers
111 views

Hamming code — identical parity bits for different errors

(7,4) Hamming Code (HC) detects all 2-bit errors and corrects all 1-bit errors. However, there can be 2-, 3- or 4-bit errors that come with the same parity bits as that of 1-bit errors. Eg.: Let ...
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1answer
118 views

use of Hamming Distance in Communication Networks

I am trying to put things in places on the use of Hamming Distance (HD) in error detection and correction in Computer Networks. I'm looking for correction/verification on the following: HD is a ...
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1answer
38 views

Why not use the channel capacity as the sliding window size?

In a sliding window protocol, if we use the maximum possible capacity of the channel as the size of the sliding window, efficiency will be theoretically 100%. What is the logic behind not doing this? ...
2
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2answers
40 views

What's the real difference between throughput and capacity of a network cable?

I was preparing a presentation in work on GPON & other optical network technologies using documentation provided by a supplier, and the claim it made was "GPON networks have a capacity of up to ...
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2answers
75 views

Till which layer does the loopback packet goes?

I want to know exactly till which layer in the OSI model the 127.0.0.1 (loopback) packet goes till it is returned to the upper layer. I read some where it goes till data link layer. but as i was told ...
0
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2answers
180 views

scale-free networks and adjacency matrix

Given a distribution over graphs with $n$ nodes having the "scale-free" property, I would like to compute for a pair of vertices $(a,b)$ the probability that they are connected (or more precisely the ...
17
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4answers
5k views

If the two generals problem is unsolvable how can we human beings agree on things?

If the two generals problem is unsolvable how can we human beings agree on things? I mean, we communicate everyday and have the same limitations as any communication problem handled by computer ...
2
votes
2answers
320 views

Algorithm for Dynamic Client Side Throttling

Problem I am trying to come up with an algorithm that will dynamically throttle a client's number of outstanding requests based on the response times of completed requests. Response times are ...
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1answer
46 views

Probabilistic Analysis in real time network : Error in data and feedback channel. Two users communication

I'm studying probabilistic analysis in real time network. We have learn how many attempts in average are required to transmit a packet when there is no error on the feedback channel. With no error ...
0
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1answer
41 views

Hamming Distance, Bit message [closed]

My professor told us to try and remember the equation used for an upcoming exam, however I'm struggling to fit the equation into the question: http://i.stack.imgur.com/RoPYG.png (need a high ...
1
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0answers
23 views

what is correct maximum number of subnetworks? [closed]

ip: 10.5.2.1 subnetmask: 255.255.255.240 {10.5.2.1/28} what is correct maximum subnetworks ???? what is different between classful subnet and CIDR subnet ???
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1answer
38 views

How can there be stop and wait protocol for a simplex channel?

Doesn't the receiver have to send back an acknowledgement frame? So how can it send back a frame, since a simplex channel only allows transmission in one direction?
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54 views

How does 4G LTE work faster than any ordinary Internet connection [closed]

How is 4G LTE faster than any ordinary internet connection? What is the mechanism behind it?
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1answer
79 views

How to compress a bit string? [closed]

I'm aware of some techniques to compress a string of characters such as Huffman coding. I need to know whether there is any technique to compress a long string of arbitrary bits? (ideally with high ...
1
vote
1answer
61 views

Sliding window protocol when number of packets is equivalent to the window size

I am currently taking a course in computer networking and I am curious about the following situation: Given $n$ packets and a window size of $n$ (i.e., the number of packets is equivalent to the ...
0
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0answers
49 views

What is the difference between disaster recovery at the data link layer and the transport layer?

What is the difference between disaster recovery in the network data transmission, when this process is performed by the link layer and the transport layer? The two approaches can be used together, or ...
0
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2answers
1k views

How to calculate probability of packet loss and drop rate?

In a queuing system (M/M/1) with a finite packet capacity $z$, how do you determine the probability of packet loss if we assume that packets are dropped when the system is full? Packets arrive with a ...
0
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0answers
31 views

hybrid or “mixed” networks

I am a mathematician, and I am completely lay in the technical aspects of computer networks and computer architecture. I would like to know if there is any computer network or architecture, protocol, ...
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2answers
651 views

Why is CAN protocol preferred to be used in automotive application?

Is it only because of the fact that it is asynchronous and can be used for long distance message transfer. An example of where other protocols will fail would help. Thanks.
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1answer
53 views

The maximum & minimum number of sources that can be multiplexed so that no data loss occurs on TOKEN BUCKET?

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 ...
3
votes
1answer
89 views

Unsplittable flow in capacitated networks

I have an undirected network with capacitated links/edges. Between some nodes unsplittable traffic has to be routed. All demands and capacities are known, but it is uncertain if all flows can be ...
1
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1answer
131 views

Why the analysis of Aloha protocol uses Poisson distribution?

Pretty much in all of the analysis of the Aloha protocol that I read, it is assumed that the distribution of packet arrivals is Poisson. What is the rationale behind it? Isn't it actually binomial ...
0
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1answer
246 views

Why escape and escape in byte stuffing?

Denoting the two special bytes as FLAG and ESC, and any other as X, where FLAG denotes the start and end of the message and ESC is used to escape any flags within the original message, if the original ...
1
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0answers
35 views

Why are there so many available loopback addresses? [closed]

I don't really know whether this is the correct site where to post this question, I'm sorry if I'm mistaken. I am studying computer networks and during the explanation of the ip protocol the ...
1
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1answer
69 views

Applying Brewer's theorem (CAP) to a single node

I'm going through Brewer's theorem and its proof by Nancy Lynch and Seth Gilbert. But the paper left me with one question. What prevents the theorem from being applicable to a single node? I haven’t ...
0
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2answers
109 views

Probability of Success in Slotted Medium Access

Suppose you have a network which uses time division multiplexing (i.e. Slotted Aloha). There are $N$ nodes each transmitting in a given slot with probability $p$. I understand that the probability a ...
1
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1answer
36 views

Aggregate Rate and Poisson Process in Aloha

I'm having a hard time understanding what is mean't by the aggregrate rate $\lambda$ and what it means for throughput in unslotted and slotted Aloha protocols. The more I seem to read about poission ...
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1answer
334 views

Which addresses belong to which network, given a fixed subnet mask?

The subnet mask for a particular network is 255.255.31.0. Which of the following IP address belongs to this network? 172.57.88,62 & 172.56.87.233 10.35.28.2 & 10.35.29.4 ...
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1answer
65 views

Find the approximate number of messages (n) that need to be tried

Find the approximate number of messages (n) that need to be tried before finding two that had the same message digest (size k) with probability 0.8. You need to find n as a function of k . What is n ...