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

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Pursuing a career in CS or related fields? [closed]

I am currently a Biochemistry major with a mathematics minor. My original plans were to go on to medical school and become and anesthesiologist but, that vision has been getting pretty cloudy for me. ...
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Ethernet HUB collision exercise [closed]

There is a simple home Ethernet network, consisting of Hub, and on it attached are the father, mother, and the son in the shape of a star. a) In a time interval T, the mother sends the sequence 1111 ...
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1answer
32 views

Choice of algorithm for hierarchical clustering for minimizing network communication costs

Suppose I have a large distributed task running on a cluster system where part of the workload is compute bound and part depends on network performance. Data transfer is not completely homogeneous ...
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1answer
28 views

How can one come up with reasonable IP subnet allocations?

An ISP has following chunk of CIDR-based IP addresses available with it: 245.248.128.0/20 The ISP wants to give half of this chunk addresses to Organization A, and ...
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22 views

What are the open problems in wireless networks? [closed]

I would like to know a list of open problems in wireless networks? I know one: capacity of interference channel.
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1answer
27 views

Layered Structures

I'm trying to check how general and valid protocol suite system ( layered structure ) are. Does anyone know if radio communication ( broadcast ) via AM or FM , for instance can be viewed in the light ...
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1answer
40 views

Selecting a M.S. in CS focus [closed]

I need to pick a focus in my Masters program. The running candidates are Networking Bioinformatics Data mining Computer Image Recognition In order to avoid this becoming a discussion, I'd be ...
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1answer
36 views

What's the point of Subnet Masks?

I'm having trouble understanding the point of Subnet Masks. I was reading a nice article on Tech-FAQ on the topic, but it has left me a bit confused. When I first heard about Subnets, it was ...
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2answers
49 views

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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1answer
111 views

Why is the throughput (performance) of the Aloha protocol ≈ 0.18?

I've read in a few places (like here that the throughput - that is, the amount of good useful messages relative to capacity - of the ALOHA protocol for networks is roughly 0.18%. But its not clear ...
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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. ...
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1answer
28 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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1answer
41 views

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

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 ...
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27 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
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0answers
206 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 ...
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1answer
177 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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31 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 ...
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1answer
37 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)?
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51 views

Why do networks need scheduling?

I'm reading up on network scheduling algorithms such as RED, ARED and WRED but I'm still not completely sure why networks need scheduling and these algorithms are necessary. Thanks!
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33 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 ...
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256 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. ...
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0answers
51 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, ...
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1answer
145 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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2answers
157 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 ...
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1answer
69 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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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 ...
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2answers
134 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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2answers
213 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, ...
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1answer
97 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 ...
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1answer
292 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 ...
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1answer
51 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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158 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). ...
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2answers
313 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 ...
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1answer
226 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 ...
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1answer
183 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 ...
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2answers
1k 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 ...
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1answer
400 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 ...
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1answer
59 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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1answer
4k 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 ...
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1answer
44 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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3answers
3k 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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1answer
176 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. ...
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1answer
366 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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2answers
64 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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1answer
82 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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1answer
66 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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1answer
76 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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1answer
681 views

Graph Theory and computer networks [closed]

What are the various graph theory techniques which are used in modelling of computer networks? Secondly, Will routing algorithms like bellmanford etc also be considered to be part of modelling ...
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2answers
134 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 ...
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2answers
73 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 ...