45 votes
Accepted

Why are so many internet protocols text-based?

When the world was younger, and computers weren't all glorified PCs, word sizes varied (a DEC 2020 we had around here had 36 bit words), format of binary data was a contentious issue (big endian vs ...
  • 13.7k
34 votes

If the two generals problem is unsolvable how can we human beings agree on things?

I disagree with other answers that the communication channel needs to be modelled differently. Malice is irrelevant, simple lost messages with any non-zero probability are sufficient to create the two ...
24 votes

Why are so many internet protocols text-based?

One advantage that might be overlooked is the ability to experiment. If you're shoving bits down the tube, you're going to need to write some utility that translates ...
17 votes

If the two generals problem is unsolvable how can we human beings agree on things?

The "unsolvability" of the "Two Generals" problem (or called "Coordinated Attack" problem) is restricted to its context, i.e., in a totally asynchronous distributed system with unreliable, untrusted ...
  • 9,259
17 votes

If the two generals problem is unsolvable how can we human beings agree on things?

Central (pun intended) to the Two Generals problem is a malicious enemy in between. Although this models an unreliable channel, it models it in a way that we normally don't encounter. In the problem, ...
12 votes
Accepted

TCP Connection Termination - FIN, FIN ACK, ACK

A TCP implementation might send a standalone FIN in the first closing segment. However, it can also send a FIN ACK, instead. The latter is strictly better: the implementation can bundle a "free" ACK ...
  • 14.2k
9 votes

Why are so many internet protocols text-based?

It's not that many internet protocols are text based. In fact, if I were to guess I'd say that text based protocols are in the minority. For almost every text based protocol you see on the internet ...
  • 589
7 votes

What is the best you can do with a noisy message?

Suppose that $k \ll n$. In that case, your friend can send you the index of the first door containing a treasure. Of the $k$ numbers you get, you pick the smallest one. If $k$ is small enough compared ...
6 votes
Accepted

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

Whether this is more efficient depends on the physical properties of the medium, not on any fundamental principle of computer science. And of course there's no reason to limit yourself to ternary ...
  • 145k
6 votes
Accepted

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

The e-mail system has no way of manipulating already sent e-mails, no. The only services I've seen which allow you to "unsend" an e-mail simply delay the e-mail being sent for a user-determined ...
  • 76
5 votes

If the two generals problem is unsolvable how can we human beings agree on things?

Because we don't need guaranteed assurance that something will happen when we have sufficient experience that tells us what is likely to happen. For example, let's say that a friend wants to meet up ...
5 votes

Why is CAN protocol preferred to be used in automotive application?

A few reasons : CAN was developed by BOSCH, which have a lot of influence in automotive equipment (engine control, braking, body, gearbox control...). BOSCH ensured that CAN killed competitors like ...
  • 1,766
5 votes
Accepted

ip/tcp packet decoding without wireshark

My guess is that what you are seeing is a Level 2 Ethernet frame and therefore the preamble is missing. Also the Ethernet checksum seems to be missing. In this case everything seems to line up (the ...
  • 24.4k
4 votes
Accepted

Why is CAN protocol preferred to be used in automotive application?

Historical reasons, for the most part. Automotive systems started using CAN because nothing else was good, and now they've all standardised on it. Having said that, CAN has one particular feature ...
  • 19.3k
4 votes

Algorithm for Dynamic Client Side Throttling

this is a fairly basic problem in control theory and there are "design patterns" in this area to handle this type of system, and think there is probably an example right out of a control theory book ...
  • 10.9k
4 votes
Accepted

Convolutional and Linear block codes

A memoryless channel is one where the probability of an error at a particular bit is independent of what happened at all prior bit positions. A channel can have memory if errors are correlated across ...
  • 145k
3 votes
Accepted

Example of reduction in communication complexity

Assume that each player gets a number in $[n]$, and they can compute $h_n(x,y)$. Each player knows $n$, so if $h_n$ is computable with less than $log(n)$ communication, they can compute $h_n(n-x,y)$ ...
  • 13.2k
3 votes

Why are so many internet protocols text-based?

Your question can be interpreted in three ways: Why is numerical data transmitted in textual representation, as if it had been printed with e.g. printf()? Why do ...
3 votes

Why are so many internet protocols text-based?

Structured binary also has limitations in expanding it. It my days of working with FidoNet and building a gateway between it and UUCP/USNET, Fidonet's message headers were a structured binary. ...
3 votes
Accepted

A query about serial data transmission

It was probably a rather unfortunate abbreviation of 8-N-1 serial transmission which is what MIDI uses. The 8 bits are sent serially, one at time, still.
  • 1,230
3 votes

Probability of Success in Slotted Medium Access

There is a clear explanation given in these lecture notes MIT course Digital communication systems (read by H. Balakrishnan and G. Verghese). The specific part that you require is this> If each ...
3 votes

Difference between CRC and Hamming Code

Both CRC and the Hamming code are binary linear codes. One significant difference is that the Hamming code only works on data of some fixed size (depending on the Hamming code used), whereas CRC is a ...
3 votes
Accepted

Difference between CRC and Hamming Code

CRC is conceived as the remainder of a polynomial division. It is efficient for detecting errors, when the calculated remainder does not match. Depending on the CRC size, it can detect bursts of ...
  • 1,766
3 votes

Link utilization of sliding window protocol

Link utilitization is about the steady state, i.e., what happens when you send a lot of data... not what happens at startup (at the very beginning of the connection). Imagine you have a humongous ...
  • 145k
3 votes

What is a "name/variable of base type" in applied $\pi$-calculus?

“Base type” is a type that isn't built from other types. Types built from other types include data structures (e.g. lists, arrays, pairs, …), functions, etc. In the context of the pi-calculus, base ...
3 votes
Accepted

Serial communication and parity bit

You may find contradictory answers because there are many kinds of serial communication protocols. Some are LSB first, some are MSB first. For example, for the old RS232 standard and siblings, the ...
  • 1,766
3 votes
Accepted

IP Fragmentation

The IP packet has to include the TCP headers in its payload. Hence we find additional 20 bytes, beyond the 3523 bytes of the sent data (the TCP payload). The total 3543 byes then get fragmented as ...
  • 14.2k
3 votes
Accepted

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

Briefly, communication between two hosts/peers on a network occurs by means of network sockets. Roughly a socket is pair (IP,PORT) of numbers which uniquely identifies a host on a network. So, when a ...
  • 9,622
3 votes

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

You can do this with $O(K \log N)$ bits of communication on average, where $K$ is the size of $|(A\setminus B) \cup (B\setminus A)|$, assuming you are willing to use a non-interactive protocol and are ...
  • 145k
3 votes

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

If you're feeling up for something particularly geeky, you might enjoy a fair exchange protocol, either one based on gradual release (see e.g., this paper) or one based on Bitcoin (e.g., this). The ...
  • 145k

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