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

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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 ...
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17 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 ...
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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 ...
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9 views

Reference for Motivation of WSN Localization in 3D

I need references to motivate the reader about 3D Wireless Sensor Network Localization problem. I have found many references about 2D WSN localization, however, there is a lack of 3D WSN Localization ...
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19 views

What is the correct term for “time to establish a connection”

I don't remember what is the term for "time to establish a connection". For example in a smartphone, when I lost the wifi signal and the phone try to get mobile data connection it spends a bit of ...
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1answer
23 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 ...
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2answers
34 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 ...
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1answer
18 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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22 views

Question from GRE subject on finding the size of transport layer

I am here to ask for guidance to a question as to how approach to such questions not seeking answer to homework ,as this question i came across in an MCQ's book.so please realize before downvoting ...
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42 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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29 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 ...
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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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41 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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38 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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25 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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42 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
45 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
47 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
146 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
117 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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103 views

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
31 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
84 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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1answer
45 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 ...
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524 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
197 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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39 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
54 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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53 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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35 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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1answer
401 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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65 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
218 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
205 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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80 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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64 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 ...
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2answers
153 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
342 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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127 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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419 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
56 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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202 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
382 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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300 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
210 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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476 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
67 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
6k 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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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 ...