Questions tagged [computer-networks]
Questions about problems that arise when you connect multiple computers to form a network.
303
questions
0
votes
0answers
10 views
Problem on probability given frame sizes and their error correction probabilities in a wireless system
I am stuck trying to solve the following question for a while
Bit error rate after demodulation in an wireless system = 1.0e-03.
The system has 4 possible frame sizes – 48 bytes, 96 bytes, 72 bytes
...
-1
votes
0answers
27 views
Why should you use IP addresses instead of hostnames when using Sockets?
I am currently trying to send Get requests to a website, and it takes longer to find the IP address than to just use the hostname. I've been told this is better but why?
0
votes
1answer
17 views
How to reconcile the different definitions of asynchrony?
There are 3 definitions of asynchrony that I know of:
In event-based programming, asynchrony refers to the execution of tasks in a non-sequential way, which may involve creating another thread. For ...
0
votes
1answer
16 views
multicasting in ethernet
I am learning this topic and there is a concept that LSB ( bit ) of MSB ( byte ) should be set to 1 for multicasting . But why we need to do so as multicast address is unique so why can't we assign ...
0
votes
0answers
11 views
What are overlay & underlaying topologies in DHT?
We are covering Distributed Hash Tables in my "Networks" class and one of the subsections is about the improvements that can be made to increase the performance of the chord. Here, the ...
-1
votes
0answers
20 views
The size of frames generated in transferring files
An application sends a $5*10^{10}$ bytes file.
The next layer breaks the file into a number of segments. Each segment carries 1400 bytes of file data and 24 bytes of headers.
Then, a segment is ...
-2
votes
0answers
17 views
Cache structure in a particular case
A memory unit consists of 64KB of main memory, 1 KB of cache memory organized in direct mapped cache the cache line consists of 16 bytes.
What is the size of address bus?
How many bits are required ...
0
votes
0answers
17 views
Storing Network Packets in Tabular Form
For network packets coming over TCP/IP protocol, have you ever confronted a situation where you need to store those network packets in tabular form similar to how tabular tables in databases? For ...
0
votes
1answer
55 views
How a 10GB network can copy 1TB data in 2 hours?
In the slides of a university lecture, the following phrase got my attention.
Assuming 10GB network, it takes 2 hours to copy 1TB.
My calculation was as follows.
10GB network = 10 gigabits per ...
-1
votes
0answers
16 views
Calculate effective throughput for file transfer
Consider a file of 3MB that needs to be transmitted over a 1Gbps link with RTT of 80ms, What is the effective throughput?
A) 36.2 Mbps
B) 9.26 Mbps
C) 9.9 Mbps
D) 28.85 Mbps
Here is what I did - ...
0
votes
2answers
24 views
Does the host operating system know the content of your messages in a messaging applications?
Let's say you are using a messaging application (Microsoft Team, Skype, Telegram,..) on an operating system (Windows, MacOS, Linux). Does the OS know what you are sending or receiving? If yes, how? ...
0
votes
0answers
13 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 ...
0
votes
0answers
30 views
Can someone explain how to calculate what time each host started and finished?
The diagram at right shows a WIFI network with an access point, X and three hosts, A, B and C. The large circles indicate the coverage areas of the three hosts. The coverage area
for X is not shown, ...
0
votes
0answers
60 views
Two Generals' Problem Definition
I've read various descriptions of the TGP, most of which seem vague or conflicting on the precise constraints of the problem. Specifically:
is it always or sometimes impossible to reach consensus
...
0
votes
0answers
14 views
Computer Networks Link layer error detection
I am aware that Link-Link error detection and correction takes place as an optimization to the error detection taking place at the Transport Layer at the destination host's end. I was wondering if ...
0
votes
0answers
9 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 \...
0
votes
0answers
19 views
Automated API negotiation
Is there a way for two programs or computer nodes to communicate with each other without knowing each others APIs? Or is there a least a reasonable approach to make them talk in some settings?
Let a ...
0
votes
0answers
14 views
Is there any guarantee in asynchronous systems?
We know that in an asynchronous system, no assumptions about process execution speeds or message delivery times are made. My question is: can we present any guarantee in asynchronous systems?
Some ...
1
vote
0answers
41 views
How do I compress data vectors in broadcast messages?
Let us model a wireless broadcast network as an undirected graph $G(V,E)$ where there is an edge between every pair of nodes ${i,j}\in V$ if they are in transmission range of each other. $w_{i\to j}$ ...
0
votes
0answers
23 views
Calculating minimum frame size
I'm actually quite stuck on a question I have for an assignment...I'd appreciate any help with this:
Consider a CSMA/CD network with maximum cable length of 8km and where the ratio of > ...
0
votes
0answers
82 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 ...
0
votes
0answers
11 views
Application for large graphs compression
I am looking for an application in which it is desired to perform an efficient lossy compression of very large graphs, that preserve the general structure of the graph but may delete some edges.
Can ...
0
votes
0answers
14 views
Finding the approximate weight of intra graph paths
Say that you have access to a source $a$ and destination $b$ in a weighted graph $G$ with $n$ vertices. There exists a path $p$ from $a$ to $b$ with 2 or more vertices in it. We know the total cost of ...
0
votes
1answer
54 views
Is it possible to transmit bits digitally?
I have learnt that all data transmission is analog. Is there any mediums that could transmit bits digitally?
0
votes
0answers
22 views
Andrew Tannenbaum exercise
A bit string, 0111101111101111110, needs to be transmitted at the data link layer. What is the string actually transmitted after bit stuffing?
There isn't any END DELIMETER given here, Answer given ...
1
vote
0answers
35 views
SSID evaluation within the 802.11 protocol
Inspired by a question on superuser, I was reading up on the 802.11 protocol. This made me wonder if the SSID is actively used outside the authentication and association process. I know that it can be ...
0
votes
0answers
14 views
network question on Go back n
A Go-back-N sender just receives an ACK packet with sequence number 𝑡. Before this
ACK is received, sender’s window is [𝑘, 𝑘 + 𝑁 − 1] where 𝑁 is the window size.
Suppose 𝑘 > 𝑁, packets may ...
0
votes
0answers
21 views
Socket API in TCP
According to me Statement S1 and S2 is True while S3 is False.
The Solution says 'S3' is correct ? Am I Wrong ? Kindly help with explanation .
I know Connect() in TCP is used by the client side for ...
0
votes
0answers
8 views
Mainstream publication venues for Internet of Things (IoT)
I am interested in reading the research literature on Internet of Things (IoT). I am especially interested in theoretical research (eg. papers where techniques from graphs or algorithms are utilized)....
0
votes
1answer
31 views
Probability of loss using a binary symmetric channel
Today we talked about Information Theory and the binary symetric channel.
For newbies here is a little explanation :
For instance if I want to send a binary to someone :
The bit will be "flipped&...
0
votes
2answers
63 views
Can we improve internet speed by serializing timestamps?
If we (scientists) came up with a way of representing numerical timestamps as letters hence reducing the number of bytes needed to represent timestamps, would that mean an improvement in internet ...
0
votes
1answer
32 views
Does an insecure router bypass the privacy guarantee of a VPN connection?
If I have a router that has a vulnerability that allows an attacker to gain full control it, does using a VPN on the network with the said router prevent an attacker from being able to snoop on the ...
1
vote
1answer
51 views
Is this applet implementation for the Go-Back-N ARQ protocol correct?
I was reading a textbook describing the Go-Back-N (GBN) protocol with Finite State Machines as pictured below:
$\Lambda$ just means "initial state" or "no action", depending on ...
0
votes
1answer
22 views
Go-Back-N Protocol not efficient?
Let's say we have five packets
p1 p2 p3 p4 p5
to be sent sequentially:
and for some reasons, p3 got delayed so it the the last packet to arrive recevier.
so below is the receiving order on the ...
0
votes
1answer
28 views
Computer networks - Can there be an out of order frames in a noiseless channel?
In a noiseless channel can frames in the 2 layer of OSI model(Data link layer) reach to the destination out of order?
*I am studying from Computer networks 5 Edition of Andrew S. Tanenbaum
0
votes
1answer
38 views
Can application DNS requests bypass a firewall on Windows and Linux
Assuming I have firewall set to block an application from accessing the Internet, would I DNS request go through?
I tried using C (gethostbyname) on Windows and the answer is no. It seems that the ...
-1
votes
1answer
48 views
What is the meaning of this error message I get when downloading documents?
Every so often I'll hop on my laptop, open google, and eventually try to download and open some document, only for the document to wind up looking like this:
What on earth does all this mean? What ...
0
votes
0answers
13 views
How to solve Bluetooth intermittent connectivity in multi hop communication?
In a specific area mobile devices are connected with Bluetooth multi-hop connectivity with intermediate mobiles for data communication purpose as per in below figure.
Now in scene 1 from source (MD1) ...
3
votes
1answer
50 views
How private IP address is determined?
Today I presented about IP address during my online class based on Computer Networks by Andrew S. Tanenbaum and during QnA session, I was asked about private IP Address range.
...
2
votes
0answers
15 views
Does RLNC (Random Linear Network Coding) still need interaction from the other side to overcome packet loss reliably?
I'm looking into implementing RLNC as a project, and while I understand the concept of encoding the original data with random linear coefficients, resulting in a number of packets, sending those ...
1
vote
1answer
34 views
Is IP masquerade and Network Address Port Translation(NAPT) the same?
Is IP masquerade and Network Address Port Translation(NAPT) the same? I'm not sure whether it is the same thing or not but I realized the mechanism is almost the same where both IP masquerade and NAPT ...
0
votes
1answer
19 views
What does route aggregation is an automatic process means?
Here is an excerpt from Andrew S. Tanenbaum, Computer Networks, 5th edition, Chapter 5 (The Network layer), page 448:
When aggregation is turned on, it is an automatic process. It depends on
which ...
0
votes
2answers
161 views
Difference between DNS Spoofing and DNS Hijacking?
DNS Spoofing and DNS Hijacking, both of them basically are type of attacks where the request is redirected to some other malicious website or some other web page. But I did not find some concrete ...
0
votes
2answers
58 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 ...
0
votes
1answer
40 views
Why NAT is a disadvantage when TCP source port field is 16 bits?
Here is an excerpt from Andrew S. Tanenbaum, Computer Networks, 5th edition, Chapter 5 (The Network layer), Page 455:
My question is on the second paragraph. From what I understand, basically this ...
0
votes
1answer
18 views
Possible error in Computer Networks, V Edition by Tanenbaum & Wetherall
Under section 5.4 Quality of Service on page 404:
Multimedia applications in particular, often need a minimum throughput and maximum latency to work.
Isn't this statement incorrect? Shouldn't it be :...
0
votes
1answer
15 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 ...
2
votes
1answer
40 views
Why does Slotted Aloha work?
So the way I understand it, if station A and station B, for example, try to transmit a frame at the same slot, a collision occurs, leading to an attempt at the next slot. But wouldn't the algorithm ...
2
votes
1answer
118 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 ...
4
votes
0answers
34 views
What are some advanced background topics I'll need for distributed systems and networks research?
I am a new graduate student in Computer Science who would like to be able to read and understand modern and new distributed systems research papers. My current background / courses and understanding ...
