Questions tagged [computer-networks]
Questions about problems that arise when you connect multiple computers to form a network.
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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, ...
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Clock synchronization in a network with asymmetric delays
Assume a computer has a precise clock which is not initialized. That is, the time on the computer's clock is the real time plus some constant offset. The computer has a network connection and we want ...
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What happens when an internet connection is faster than the storage write speed?
If one attempted to download a file at a speed of 800 Mb/s (100 MB/s) onto a hard drive with a write speed of 500 Mb/s (62.5 MB/s), what would happen? Would the system cap the download speed?
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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 ...
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Measuring one way network latency
This is a puzzle about measuring network latency that I created. I believe the solution is that it's impossible, but friends disagree. I'm looking for convincing explanations either way. (Though it is ...
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How does a wifi password encrypt data using WEP and WPA?
How does the password that we enter (to connect to a wireless network) encrypt the data on the wireless network?
Through my reading I am not sure if the password that we enter is the same as the ...
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TCP Connection Termination - FIN, FIN ACK, ACK
I've been reading that to terminate a TCP connection 3 handshakes are required: FIN, FIN ACK, and ACK. However, when closing a connection, Wireshark displays FIN ACK, FIN ACK, ACK; it never displays ...
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Can the end-to-end principle be formalized?
In the late 1990s, when I was in graduate school, the paper
JH Saltzer; DP Reed; DD Clark: End-to-end arguments in system design. ACM Trans. Comput. Syst. 2(4):277-288, 1984. DOI=10.1145/357401....
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Analysis of and references for Koch-snowflake-like (and other exotic) network topologies
In computer networking and high-performance cluster computer design, network topology refers to the design of the way in which nodes are connected by links to form a communication network. Common ...
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What is the growth rate of the world wide web?
Is there any way to estimate how much data is added to the world wide web each second? Are there any studies about this?
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Weak hashing function for memorable IPv6 addresses
IPv6 addresses in the form of 862A:7373:3386:BF1F:8D77:D3D2:220F:D7E0 are much harder to memorize or even transcribe than the 4 octets of IPv4.
There have been ...
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What techniques exist for energy-efficient computing and networking?
I am currently reviewing the potentials of cloud computing regarding energy efficiency and green IT. In connection with this review I am having a look on techniques for increasing energy-efficiency in ...
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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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Link utilization of sliding window protocol
Before I ask my doubt I would like to state that problem which led me to my doubt. It can also serve as a good example scenario.
A $20\ Kbps$ satellite link has a propagation delay of $400\ ms$. ...
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Why is it seemingly easier to resume torrent downloads than browser downloads?
I really wonder how torrent downloads can be resumed at later point of time.
If such a technology exists, then why is it not possible in browsers?
It is often not possible to pause a browser download ...
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Why is the throughput (performance) of the Slotted Aloha protocol ≈ 0.36
I've read that the throughput - that is, the amount of good useful messages relative to capacity - of the Slotted ALOHA protocol for communication networks is roughly 0.36%.
But its not clear how we ...
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Transmission (Store and Forward) Delay
The Kurose & Ross book uses "store-and-forward delay" as a synonym for the transmission delay of a packet over a network link.
As a newcomer to computer networks, it isn't immediately obvious to ...
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Bipartite Graph Game
So say we have a bipartite graph G=(X,Y,E). Let's make a game out of it.
I go first. I pick a node in X. You go next. You pick a node in Y that is connected by an edge to the node I picked. Next it's ...
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How to ensure connectedness in a masterless gossip protocol?
This is a theoretical question about how gossip protocols work; I am not asking about any specific implementation or piece of software.
I've read the wikipedia page https://en.wikipedia.org/wiki/...
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Why is TCP known as reliable protocol?
Is it because it uses 3 way handshaking, it is reliable? Or is it due to other reasons? Like due to congestion control, flow control and error control in TCP? Why do we call TCP as reliable?
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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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Message receipt verification in a cluster
At my current project I had a network problem come up for which I could not find a solution. In a peer-to-peer network I needed to send an action to all peers, and each peer was to act on it only if ...
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Why is the vulnerable time in pure aloha twice the frame time?
The time required to send a frame is called frame time.
Vulnerable time is the time during which no transmission should be done to avoid any collision.
My question is what kind of problem will be ...
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Go Back N ARQ Question
I am a computer science under graduation student, and was going through some Go Back N ARQ (Computer Networking) videos on YouTube, and got a doubt in a question, which according to me should have a ...
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What is the difference between transmission delay, queuing delay, and processing delay?
My book defines queuing delay as the time the packet waits to be transmitted onto the link. It defines transmission delay as the amount of time required to push all of the packet's bits onto the link. ...
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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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How come Datagram Packets between same source-destination pair may take different routes?
This might be a rookie question, but I wanted to understand the following line.
My book says, each time a host wants to send a packet, it places the address of the destination host in the packet's ...
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Why 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 ...
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What areas in EE overlap closely with CS
I am doing bachelors in Electronics & Communication Engg.. But most of my work happened to be in Web development.. I am thinking to do my bachelor thesis which very closely overlaps with my recent ...
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How would the Internet work between planets?
Say that in the future there are people on other planets, e.g., Mars. The one-way communication delay to Mars is between 3 and 21 minutes.
Say we want to connect the people on Mars to the Internet. ...
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How to make smart contracts work in a small network?
Suppose we have a small computer network, there are 30 random people who have provided their computers to perform any computational tasks on them. Let's call these 30 computers nodes. We can access ...
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How to generate a connected random network topology for a specific number of nodes?
I'm trying to generate a random but realistic network topology so I can test the performance of some routing algorithms. I came across Waxman's model described in Routing of Multipoint Connections, ...
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What are some advanced background topics I'll need for distributed systems and networks research?
I am a new graduate student in Computer Science who would like to be able to read and understand modern and new distributed systems research papers. My current background / courses and understanding ...
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totally ordered multicast with Lamport timestamp
I'm studying Distributed Systems and synchronization and I didn't catch this solution of totally ordered multicast with Lamport timestamps. I read that it doesn't need ack to deliver a message to the ...
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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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Does UDP always deliver packets inorder to the application layer
I was reading about UDP and TCP. TCP is a stream-oriented, connection-oriented protocol and always delivers the segments in order to the application layer.
But UDP being connectionless, does it also ...
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How to distinguish between bits?
I read a post about differences between synchronous and asynchronous transmission modes.
That post has a picture about how bits flows from terminal to computer in async mode.
But how computer can ...
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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 ...
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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 ...
user65539
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Analyzing Twitter Relationships
I'm not even sure if this is the right StackExchange to post this, but it seems like sentiment analysis would go here.
What would be the best approach to determine if two people on Twitter are ...
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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 ...
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Hashing methods for validating dowloaded files
The standard algorithm to generate hashes of files which are downloaded is MD5. For example, when ISO files of Linux distributions are offered most of the time they also give the MD5 sum so that you ...
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Combine the following IP Addresses into a single block
I was asked to combine the ip addresses into a single block:
16.27.24.0/26, 16.27.24.64/26, 16.27.24.128/25
I managed to convert the given ip addresses into binary:
00010000.00011011.00011000....
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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 ...
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How does a single-node system get Availability in CAP theorem?
I have a question. I read many blogs, websites about CAP theorem. They say that single-node systems are CA, but how can it be "A" if that single node goes down ? Because if it does, the ...
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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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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), ...
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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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CSMA/CD with binary exponential backoff: Do both back off or just the loser?
I've been given two PC's that are connected via Ethernet, and as such are using CSMA-CD with binary exponential backoff.
Now, both PC's, let's call them $A$ and $B$, are trying to send data ...
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We can control tcp/udp traffic using router. Then why is it in Network layer and not transport layer?
Routers make use of the IP address, etc to shape the traffic. So obviously they must reside in at least the Network layer.
However we can also shape the traffic using tcp/udp. Routers usually have the ...
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