Questions tagged [communication-protocols]

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rendezvous vs normal synchronous send and receive

From what I understand, rendezvous is a message-passing technique where both the sender and receiver are blocking (synchronous) and the receiver acknowledge the send in a binary handshake between them....
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49 views

Tearing down the FSM description of congestion control

I was going through the text Computer Networking- A Top-Down Approach by Kurose and Ross, there I found subtleties with the TCP congestion control FSM which is shown below: Mainly I am having ...
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12 views

How does RCS compare to extending text message protocol?

Text message constantly keeps adding more emoji so I know the protocol could be extended with a delimiter at minimum. How does RCS compare to extending text message protocol? I ask this because I ...
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16 views

Compressing the output of a discrete memoryless channel

Let $x\in \mathcal{X}$ be a symbol from an input alphabet, let $p(y|x)$ be a conditional probability distribution corresponding to a discrete memoryless channel and let $y\in\mathcal{Y}$ be an output ...
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16 views

modelling communication costs on a network

Consider a set of $N$ computers. Each computer needs to send some data to $K$ other computers, and each computer is receiving data from $K$ other computers (ie. the communication pattern can be ...
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13 views

Throughput of slotted ALOHA when one node goes out of sync

What would be the throughput of slotted ALOHA when one node goes out of sync? Closer to ALOHA or slotted ALOHA? According to my calculations: For ALOHA we have probability of success = $N \cdot p \...
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308 views

Decode TCP Payload data

I'm trying to find out what the data of a packet means. I'm a newbie to networking, and I try to find what's sent in this packet: https://pastebin.com/hZEqjmBx How can I do that? What does that data ...
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1answer
39 views

Complexity of two-party maximum

Given function $\max\colon \{0, 1\}^{n} \times \{0, 1\}^{n} \rightarrow \{0, 1\}^{n}$ that returns the maximum of two binary $n$-vectors (interpreted as encoding numbers in the range $0,\ldots,2^n-1$),...
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67 views

Why are processes on the internet not required to use TCP or UDP?

Here is an excerpt from Andrew S. Tanenbaum, Computer Networks, 5th edition, Chapter 5 (The Network layer), Page 455: [Fifth, processes on the Internet are not required to use TCP or UDP. If a user on ...
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1answer
25 views

MAC protocol with throughput of 1

Consider a MAC protocol (ALOHA, CSMA, TDMA, etc.) that, even for very high loads, always results in a throughput of 1 (normalized with respect to the channel speed). Why is that not good if the ...
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1answer
131 views

'Half-Close' figure of Data Communications and Networking, 5/e

In the Figure 24.13 of Data Communications and Networking, 5/e the first ACK message from the server holds y-1 in it's Sequence no. field. Note that the first FIN ...
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1answer
37 views

Communication Complexity for Product Distributions

In general for the (two-party) set disjointness problem for inputs of length n, we know that the parties need to communicate $\Omega(n)$. Surprisingly, today I discovered (if I understood correctly) ...
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25 views

tcp congestion avoidance

I came across this question: ...
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2k views

ip/tcp packet decoding without wireshark

How can we manually read and interpret packets properly without using wireshark? Now from the Ethernet header I know that the Destination MAC Address should be at the 5th byte (after converting bits/...
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53 views

Sending infinite frames in One-Bit Sliding WIndow Protocol?

I am reading Computer Networks by Andrew S. Tanenbaum and I wonder if there is a mistake in the protocol as I can't find any solution for the following scenario. Suppose the transmitter (A) has only ...
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2answers
92 views

What are the underlying mechanisms allowing us to unsend an email?

I am currently studying Computer Networking, and I was reading about the different types of Application Layer Protocols. In the book I am reading (Computer Networking: A Top-down Approach) it is ...
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24 views

Auxiliary random variables in the analysis of the private information of wiretap channels

I am following Section 13.2 of Mark Wilde's book. I reproduce the question here for completeness. Consider a wiretap channel $X\rightarrow Y,Z$ defined by the conditional probabilities $p(y,z|x)$ for ...
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79 views

What is the name of this experimental OS?

I am trying to find an OS that had a network to verify it's users. It classified itself in classes going from greatest signifigance to least, and the names were galaxy, system, planet, comet etc. I ...
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1answer
31 views

Guaranteed existence of a blocking set in the accept definition of Stellar

In the SCP, condition 2 of the accept definition allows a node to vote for one statement and later accept a contradictory one. Condition 2 assumes the existence of a v-blocking set which has not only ...
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1answer
96 views

Where were the ideas of vote, accept and commit phases originally introduced?

In the Stellar Consensus Protocol SCP, the voting procedure follows a 3 phase commit i.e. vote, accept and confirm i.e. see section 5. Is this a novel introduction or has this been previously been ...
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263 views

Is a "protocol" a set of algorithms and data structures?

I'm not major in science at all and would like to verify whether my understanding is correct or not. I just did some googling about the definition of protocol, such as in this, this one, this one and ...
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164 views

Is the capacity achieving input of a discrete memoryless channel unique?

Consider a classical discrete memoryless channel (DMC). Let $p$ be an input probability distribution and $Q$ be the channel's transition matrix. $q = Qp$ is a valid output probability distribution. ...
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23 views

Go Back N question(netwrok)

Hello I am trying to understand the GBN protocol and I encountered the following question during my homework. Assume that we have GBN protocol with a window size of 20. The sender sends 15 packets ...
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1answer
258 views

Basic Question in networking - why max data size of ip datagram 65535 BYTES and not 65535 bits?

I recently started computer networks with some understanding of algorithms and discrete mathematics. I am completely new. Kindly elaborate following - data size of ip datagram = 16bits. So with this $...
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1answer
44 views

Reaching Shannon capacity of a channel

Suppose I have the following from alphabet $\mathcal{X} = \{0 ,1\}$ to $\mathcal{Y} = \{0 ,1\}$. The channel simply does \begin{align} 0 \rightarrow 0&\quad \text{with probability 1} \\ 1 \...
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1answer
196 views

Finding maximal and average number of time slots in an Adaptive tree walk protocol

Tried to research here and on other sites with no luck regarding finding the maximal and average number of time slots in an Adaptive tree walk protocol. i'll explain what i mean here: In a simple(...
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1answer
20 views

Can a transcript change dependent random variables into independent variables?

Let's say $X, Y$ are dependent random variables. Can I find an example such that for a transcript $t$ conditioned on a communication protocol $\Pi=t$, the variables become independent?
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1answer
57 views

Looking for two-way communication/consensus/contract algorithm for use in marriage proposal

I am looking for some sort of communication or consensus algorithm with the following properties: Can be used with just two parties (and ideally doesn't collapse to a trivial case with two parties) ...
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186 views

utilization of bitmap protocol

I am curious about utilization calculation in the bitmap protocol. especially if there's a difference between if only station 0 wants to broadcast(and the others doesn't) or only some other station ...
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28 views

Affects of altering a line in "stop and wait" protocol(no noises)

what will happen if we change "to_physical_layer(&s)" to "to_physical_layer(&r)" in the following code(marked in the code where)? does it make the protocol fail? if so, show a scenario it ...
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1answer
332 views

How is the literal meaning of "rendezvous" related to its usage in distributed computing?

I am trying to figure out the difference between RPC and Rendezvous. Is it correct that they differ only on their implementation on server side: RPC will involve creating a new process/thread to ...
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1answer
134 views

Complexity of sending an $n$-bit string

Consider a $2$-party communication model in which $A$ wish to send to $B$ an $n$-bit string. It is very easy to prove that any deterministic protocol for this problem requires $\Omega(n)$ bits to be ...
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1answer
117 views

Randomized communication complexity of indexing

The function $\mathrm{INDEX}:\{0,1\}^n\times\{1,\dots,n\}\to \{0,1\}$ is defined as $$\mathrm{INDEX}(x,i)=x_i,$$ where $x=x_1\dots x_n$. I am looking for the randomized communication complexity of $\...
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65 views

How to decide which bytes will form a packet ?(computer networks)

In wireless communication , I understand what it means to transmit a "bit" but I wanted to understand what exactly does it mean by a packet . *******POST EDIT/RECEIVING INITIAL ANSWERS******* I got ...
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1answer
97 views

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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1answer
85 views

The role of the root switch after Spanning Tree Protocol has established a tree network in a LAN?

In Spanning Tree Protocol, a root switch is selected at first, and then somehow, the shortest path from each other switch to the root is obtained. Thus we established a tree network. My questions ...
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21 views

Why Not To Take B8ZS with encoding 7 digit?

I have a simple question. In signal encoding we have B8ZS (Bipolar with 8 zeros substitutions) technique which encodes every 8 sequencial 0 bits with 000+-0-+ or 000-+0-+ depends on previous voltage ...
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2answers
32 views

When packets are not full?

When in computer networks it happens that the packets are not full? I have heard that sometimes in UDP that happens, if that’s the case, why not all the space is not used?
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22 views

Is it possible to give a guarantee about the accuracy of the local time?

Assuming there is no attack/bug and I use NTP: Are there any formal guarantees about the accuracy of the local time? Can there be any over the network? Even if the communication is going directly ...
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224 views

Finding the total capacity of two communication channels

I have the transition matrices of two communication channels. I am able to find the capacity of each by performing an optimization calculation, however I need the total capacity of the two channels. ...
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1answer
32 views

Is there an existing protocol where a sender does not know who he is sending data to?

I was thinking about how the BitTorrent protocol automatically gives every peer a list of IPs of every other user who is currently seeding / leeching off the torrent in question. Is there an existing ...
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335 views

Could a standardized ternary system be more efficient than the binary system? [duplicate]

Could a standardized ternary (base-3) system be more efficient than the binary (base-2) system? Binary is efficient for processing using logic gates, but can be bulky when using for file storage or ...
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1answer
116 views

Chord protocol - How should I go about mapping nodes to placeholders on the ring?

In the real world, how is a node mapped to the position on the ring, Each nodes's IP address is hashed using SHA-1 hashing algorithm which will produce this hash - 73.128.154.69 hashed into ...
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2answers
771 views

Why is RTS/CTS optional?

I was reading in Wikipedia about it and one of the main things that were pointed out was that it is only an optional mechanism. This bugs me more than it should as I cannot find any information that I ...
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1answer
58 views

Compute the union of two sets between two endpoints minimizing communication complexity

I have two endpoints, $a$ and $b$, that can communicate through a channel. $a$ is storing a set of fixed-length strings $A = \{a_1, \ldots, a_{N_A}\}$, and $b$ is storing another set of fixed-length ...
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137 views

Probability in Dynamic frame aloha

If I've RFID Collision Arbitration System that is based on multi-frame dynamic frame ALOHA. How can compute the probability of the average tag resolution $L_n$? ,$P_s$ is probability for packet ...
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1answer
80 views

Is data received after transmission immediately stored and can that be recovered?

When I send a message from one device to another, during the process during which the other device is receiving the data, is that data stored temporarily on some place on the device or is it ...
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1answer
86 views

IP Fragmentation

I have an IPv4 packet, 3523 byte of information Data a MTU (maximum transmission unit) of 516 (496 byte + 20 byte IP header), also an TCP header with 20 byte. How does this result is created from the ...
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32k views

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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1answer
582 views

Serial communication and parity bit

I was revising Computer Science and I got these two doubts to which I've found contradictory answers on Google: In a serial communication which bit is sent first? When using a parity bit with ASCII ...