Questions tagged [computer-networks]

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

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-1 votes
1 answer
141 views

TCP repeated acknowledgement

My professor has asked this (exam) question and it actually makes no sense to me: TCP offers a reliable, bidirectional byte stream over the best effort packet delivery in IP. For reliability, a ...
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-2 votes
1 answer
2k views

What is the maximum achievable throughput in this communication using sliding window protocol? [closed]

Station A is sending data to station B over a full duplex error free channel. A sliding window protocol is being used for flow control. The send and receive window sizes are 6 frames each. Each frame ...
2 votes
2 answers
3k views

Why does packet data don't need trailer/footer while frame needs it?

Why does packet don't need trailer/footer while frame needs it? I am trying to understand networking concept regarding OSI & TCP/IP layering. I have googled a bit and it says that the footer in ...
3 votes
0 answers
5k views

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 ...
1 vote
1 answer
501 views

Can we break the Shannon capacity? [closed]

I have a friend working in wireless communications research. He told me that we can transmit more than one symbol in a given slot using one frequency (of course we can decode them at the receiver). ...
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0 votes
0 answers
75 views

Picking an optimal initial congestion window size (high bw, high latency and short bursts)?

What is a known strategy to approach a situation where short bursts of data are being sent very often over a high bandwidth, high latency cable? I am aware of cubic but even that does not utilize a ...
  • 221
-1 votes
1 answer
354 views

ARQ Protocols and sequence numbers [closed]

What will happen if sequence number is not used in an ARQ protocol (e.g, Go-back-N, selective repeat)?
1 vote
0 answers
74 views

Buffering packets vs. low latency routing [closed]

I am considering strategies to compare the performance of routers with buffers vs. their lower latency counterparts in a simple network setting (N clients communicating with each other randomly ...
  • 221
3 votes
3 answers
14k views

Sliding window protocol, calculation of sequence number bits

I am preparing for my exams and was solving problems regarding Sliding Window Protocol and I came across these questions.. A 1000km long cable operates a 1MBPS. ...
  • 141
1 vote
0 answers
401 views

Closed network system that use OSI model to connect to another network?

The OSI model can be used for LAN and WAN networks, allowing the interconnection of [vendor] closed systems and it only informs what each layer have to do. Someone said that this phrase is false, ...
0 votes
1 answer
1k views

Physical layer services & hardware protocols [closed]

I am searching the content of this topic but I am not sure what should be the content for this topic. This is relate to Computer Network. My topic is ...
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1 vote
2 answers
2k views

TCP congestion problem

Consider an instance of TCP’s Additive Increase Multiplicative Decrease(AIMD) algorithm where the window size at the start of the slow start phase is 2 MSS and the threshold at the start of the first ...
1 vote
1 answer
385 views

How to present ping data from ICMP timestamp

The ICMP timestamp protocol is useful for determining which path — forward or reverse — is contributing to the jitter on the line. In an ideal world, all computers would have an excellent ntpd, and ...
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1 vote
0 answers
331 views

NTP: synchronisation of time between two machines for ICMP timestamping

Some guy on the internet recommends using the same ntp server when it is required to troubleshoot asymmetric routes through ICMP, and it's somewhat important to have synchronised time between the two ...
  • 191
5 votes
2 answers
2k views

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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4 votes
2 answers
3k views

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, ...
1 vote
1 answer
2k views

difference between propagation speed and bandwidth in digital communication

I want to know difference between propagation speed and bandwidth in digital communication.I know bandwidth is no of bits in one second and propagation speed of signal is distance traveled by signal ...
0 votes
1 answer
3k views

need of error control in transport layer

I want to know why error control is used in transport layer although it is used in data link layer?While data link layer has all data came from upper layers in its frames so its error control should ...
4 votes
1 answer
206 views

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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2 votes
0 answers
2k views

TCP delayed duplicate problem

The TCP(Transmission Control Protocol) delayed duplicate problem is discussed in Tannenbaum's "Computer Networks." The discussion references Tomlinson (1975) improved by Sunshine and Dayal (1978). ...
1 vote
2 answers
2k views

How does DNS work if there is no recursive querying?

Suppose I type in the website www.youtube.com. The computer first asks a local domain name server (DNS) what the IP address of this website is. If it can't find it,...
1 vote
3 answers
8k views

Difference between encoding and modulation in transmission

What is the difference between encoding and modulation? I have seen these terms used sometimes inter-changeably and sometimes differently (the ratio is 50:50). Can somebody clearly explain this with ...
  • 113
-1 votes
1 answer
583 views

Little's law and average time on a system with a switch

We have a switch with $2$ lines of input and $2$ output. Each line is $10 Mbps$. The size of packets is fixed and is $1KB$. The $1^{st}$ line of input is active (transferring packets) $40\%$ of the ...
4 votes
2 answers
13k views

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 ...
1 vote
1 answer
2k views

Average number of slots needed in slotted-Aloha

Consider 2 stations that share the same bus. Both stations are perfect synchronized each other and when they have packets to transmit, they are starting the transmission in the beginning of a same ...
1 vote
1 answer
255 views

IP addresses and Subdomains?

If a school has an IP that's like 10.0.x.x, and a department in that school has it's own site that's an extension of the school's site, does that department's IP just change the last two numbers in ...
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0 votes
1 answer
20k views

Performance differences between Go-Back-N and Selective Repeat ARQ protocols?

This is what I know: GBN weakness is the fact that when the window size is too large, the number of packets in the pipeline grows and one packet error causes the retransmition of many packets ...
1 vote
1 answer
77 views

What is $R_\min$ in this formulat for optimal buffer size?

I read a question from my recitation about optimal buffer size. As solution there is a furmula for calculating the optimal buffer size; I'm not sure about one of its parameters. The formula is $\quad ...
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0 votes
3 answers
27k views

RTT (Round Trip Time) calculation

How do I calculate RTT, do I start to measure the time from the beginning of the segment transmition or from the moment all the segment had been transmitted? The end time is the moment the sender ...
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1 vote
1 answer
818 views

Simple routing table question

I'm having difficulties understanding the solution to the following question: Consider the following description of a LAN: The main Internet connection is connected to our gateway router. This ...
0 votes
1 answer
1k views

Jamming signal useless in CSMA / CD?

I'm looking at collision detection in communication protocols, in particular Carrier sense multiple access with collision detection (CSMA/CD). According to what I've read on Wikipedia, a collision ...
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0 votes
3 answers
831 views

P2P and C/S, is it possible to determine which one is more bandwidth consuming?

In peer-to-peer (P2P) networks nodes are interconnected with each other. In client/server (C/S) networks clients talks to the server. If in a C/S network clients also want to talk with each other (...
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1 answer
117 views

Names of Softwares used for modeling

Which tools or softwares are mostly used for the purpose of modeling a computer network?
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0 votes
1 answer
378 views

RDT2.1 - does the Sender listener to "ack" even though state=ready?

Computer Networking: A Top Down Approach Featuring the Internet, Jim Kurose, Keith Ross Addison-Wesley 4nd edition , page -223. Also here slide 60 . RDT2.1 (Reliable data transfer) - ...
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1 vote
1 answer
140 views

Routing Algorithms and Hosts

I'm reading a book about computer network theory, and one topic is discusses is routing algorithms. It only mentions (probably not intentionally) how routers participate in forming the understood ...
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3 votes
2 answers
168 views

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 ...
4 votes
2 answers
126 views

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 ...
10 votes
2 answers
867 views

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 ...
5 votes
3 answers
444 views

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 ...
10 votes
1 answer
463 views

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?
7 votes
1 answer
271 views

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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1 vote
1 answer
58 views

How will broadcast behave with a certain capacity?

I wanted to confirm something and will appreciate your help. Suppose we have three nodes called A,B and C. All are connected to a switch whose port supports 1 Gbps. Now suppose, Node's A network card ...
12 votes
2 answers
5k views

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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21 votes
4 answers
9k views

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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10 votes
1 answer
282 views

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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39 votes
6 answers
9k views

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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