Questions tagged [communication-protocols]

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Negotiating a connection between two devices that can't transmit and receive simultaneously

I've got a bit of a puzzle here that sits at the intersection of mathematics and technology. Hopefully this doesn't fall into brainteaser territory - I'm not sure a neat solution is possible! I have ...
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2 answers
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Communication protocol so that messages are read "synchronously"

Is there a communication protocol that ensures that both parties can read the other one's message at the same time (or at the very least, only after sending their own message, thus no party can read a ...
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1 answer
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why use bellman-ford instead of Dijstra in RIP routing?

The RIP routing protocol was published in 1988 and uses Bellman-Ford algorithm to calculate shortest path. Also more recent version of RIP (RIPv2 and RIPng) use the same algorithm. The Djikstra ...
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If I open & connect with 1 protocol to every port (all 65535) can we still open another protocol socket?

I understand and have googled how TCP & UDP can work simultaneously BUT does this assume there are unused ports to dynamically allocate? So if all ports are used by TCP can UDP still connect & ...
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Vulnerable Time in ALOHA

Why do we not consider the Propagation Delay (Tp) and only the transmission delay(Tt) while calculating the Vulnerable Time is ALOHA? A collision may occur even after the frame has been put on the ...
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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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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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429 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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1 answer
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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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2 answers
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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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1 answer
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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 ...
2 votes
1 answer
154 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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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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tcp congestion avoidance

I came across this question: ...
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1 answer
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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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2 votes
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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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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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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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1 answer
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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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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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1 answer
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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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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 ...
2 votes
1 answer
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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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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 ...
1 vote
1 answer
331 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 $...
1 vote
1 answer
51 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 \...
2 votes
1 answer
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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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1 answer
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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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1 answer
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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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203 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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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 ...
2 votes
1 answer
446 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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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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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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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 ...
3 votes
1 answer
106 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), ...
1 vote
1 answer
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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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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 ...
-1 votes
2 answers
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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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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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3 votes
2 answers
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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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1 answer
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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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5 votes
1 answer
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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 ...
0 votes
1 answer
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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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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 ...
4 votes
1 answer
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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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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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1 answer
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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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2 votes
1 answer
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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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10 votes
1 answer
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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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