Questions tagged [computer-networks]
Questions about problems that arise when you connect multiple computers to form a network.
268
questions
2
votes
0answers
17 views
Finding the timestamps of processes implementing Lamport's clocks
I have been asked this question, but don't know how to go about answering it.
Three process, which are implementing Lamport's clocks, are running and a lot of events are taking, place including some ...
0
votes
1answer
22 views
Manually Performing ECB & CBC
I am learning about block ciphers and while I understand the concept of Electronic Codeblock mode and cipher block chaining, I could not find any relevant practical examples online. Can someone ...
0
votes
1answer
30 views
assigning addresses in ipv4 forwarding
Keeping in mind this diagram, I had to assign ip addresses to the eth0 / eth1 interfaces for all the routers (r1 etc). I don't understand how to do so. Perhaps it has to do with the IP ranges.
For ...
0
votes
1answer
11 views
Proper network address
Which of the following are proper network (not host) addresses?
192.168.23.0/24
193.205.16.132/26
172.16.4.0/20
10.57.13.64/28
How can I tell? What is a proper network address?
Is a proper network ...
1
vote
1answer
21 views
binary representation of ip prefixes
How does an ip prefix
90.0.0.0/4
translate to
0101∗
in binary
and
10.0.0.0/2
to ...
1
vote
1answer
14 views
What is the the relation between the amount of data transmitted and line distance?
I am wondering what is the relation between line distance and the amount of data transmitted on that line. I know the basic of computer science only. let's say I want to calculate the time it takes ...
0
votes
1answer
21 views
RPI cluster performance related to network performance
I'm writing my thesis and i have built a RPI cluster, containing 10 nodes which consists of RPI model 3b. I've them connected to two gigabit switches. I don't know the CAT of the cables. They are not ...
1
vote
2answers
20 views
encrypt with permutation ciphers
I came across this question:
You are given a permutation cipher defined by the bijection t: N -> N where,
...
0
votes
1answer
18 views
0
votes
1answer
34 views
network address translation
I'm having some difficulty understanding ip addresses. Let's say:
Question Info:
private subnet 192.168.0.0/24
IP addresses 212.201.49.1-5
Now, a host 192.168.0.2:1234 retrieves a web page from ...
0
votes
1answer
75 views
ip/tcp packet decoding without wireshark
How can we manually read and interpret packets properly without using wireshark?
Let's say I have this data (IEEE 802.3 link):
Now from the Ethernet header I know that the Destination MAC Address ...
-1
votes
1answer
20 views
Why do we need to connect the computers to a LAN cable when we can use the internet [closed]
why don't we put a network card or usb adapter to connect to wifi and connect all the computer to the internet without LAN and WAN cables
i may act stupid so please explain it to me my friend
1
vote
2answers
57 views
Decryption of RSA
How can we decrypt an RSA message if we only have the public key?
For example,
Message:
21556870,12228498
Public Key: ...
0
votes
1answer
32 views
Duplicating ACKs and Window Sizes
After reading an answer at this link:
https://serverfault.com/questions/503345/three-duplicate-acknowledgementss
I am confused. Do ACK values repeat when a packet is lost or when an out of sequence ...
0
votes
1answer
20 views
data carried during TCP control flow
I am learning about TCP control flow and came across a question about how much data is carried by the 4th segment. The answer is supposed to be 1200 (2230 - 1030) but I don't quite understand why.
...
0
votes
1answer
23 views
Urgent Flag of TCP, Computer Networks
The Urgent Flag(URG) is set whenever the sender's Application Layer wants to send some urgent data to the receiver. In this case, the Transport Layer does not wait for enough data to achieve maximum ...
1
vote
1answer
18 views
About P2P networking
In P2P(peer-to-peer) networking, it is possible for the server program(software) and the client program(software) to be running on the same computer.
So the two must have the same IP address.
I am ...
1
vote
2answers
48 views
What happens when there are two same IP addresses?
IPv4 addresses run out few years ago. But everywhere I can see mine or someone elses IP address it's in IPv4, not IPv6. I understand that world switched to IPv6? So why we can see address in older ...
1
vote
1answer
38 views
Understanding connection between length of codeword and hamming distance in Hamming code
I came across following in Huffman coding:
Minimum Hamming distance to correct up to s errors is $2s + 1$ because that way the legal codewords are so far apart that even with $s$ changes the ...
2
votes
1answer
72 views
Why does $x^{15}+x^{14}+1$ detect all errors at most 32768 bits apart?
Reference Question from Forouzon Book Computer Network.
Find the status of the following generator related to two isolated, single-bit errors.
$$x^{15} + x^{14} + 1$$
Answer given :
This polynomial ...
1
vote
0answers
22 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 ...
1
vote
2answers
84 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 ...
0
votes
0answers
14 views
Good citation/source for size of the internet
I am writing an introduction for a paper and want to cite something for a sentence such as "over the past thirty years, the internet has grown from hundreds of nodes to blah blah blah" (basically ...
0
votes
0answers
15 views
Count to infinity problem (routing) between unsynchronized stations(tricky)
i was wondering, will count to infinity can occur in the following cases? if so, will it necessarily occur or can the routing tables stabilize themselves?
Distances:
From A to B - 3
from B to C - 4
...
1
vote
1answer
28 views
S/Kademlia dynamic crypto puzzle
In S/Kademlia two crypto puzzles is used, one static and dynamic. The static is used to generate a key pair that makes an eclipse attack difficult to achieve, the dynamic to make Sybil attacks harder. ...
0
votes
0answers
19 views
IGMP Multicasting
The definition about IGMP on the internet goes like this-->
The Internet Group Management Protocol (IGMP) is a communications
protocol used by hosts and adjacent routers on IPv4 networks to
...
0
votes
0answers
10 views
distance of a code name in scheme
i wonder: is it true that if we take a information word, call it M(with m bits) for example, and code it by first coding M using a code, that we don't know anything about, except of it a length of k, ...
0
votes
0answers
39 views
Expected number of retransmissions for a packet
In a communication link out of p packets one packet will be lost. If stop and wait protocol is used then expected number of retransmissions for a packet?
(A) P/(1-P)
(B) P
(C) 1/(1-P)
(D) 1/P
...
0
votes
1answer
53 views
Probability of detecting errors in codewords
I have been struggling with the below question for quite some time, and I don't have a pointer to move forward.
A certain Error Control Coding scheme using block codes takes an input block (...
0
votes
0answers
33 views
Stop and Wait protocol in a half duplex scheme
glad i found this site. would appreciate help with this: in picture i uploaded there's a state diagram of a "stop and wait" protocol in a half duplex channel. we assume current status is (10A).
...
0
votes
0answers
25 views
P2p versus Client Server Architecture: Performance
I want to understand the difference between P2P and Client server Architecture in the context of Performance. Book has drawn a graph. The link of the book is:
Computer Networking: A top-down ...
0
votes
0answers
29 views
TCP congestion control problem
Suppose that the maximum transmit window size for a TCP connection is 12000 bytes. Each packet consists of 2000 bytes. At some point in time, the connection is in slow-start phase with a current ...
0
votes
0answers
17 views
fragmentation in ipv4 is done at source or routers or at both
fragmentation in ipv4 is done at source or routers? according to what i read, fragmentation can be avoided at source, by doing segmentation at transport layer wisely to match MTU of source network... ...
2
votes
3answers
154 views
Is the constant pi (not Raspberry) ever used in general computer science?
Is the constant pi (not Raspberry) ever used in general computer science? If so, how so or when is it applicable?
0
votes
0answers
75 views
Are acknowledgements used in CSMA/CD?
To provide context, I have read that CSMA/CD does not rely on acknowledgements and relies on collision signals to check for successful or unsuccessful transmissions (from what was explained in the ...
0
votes
1answer
28 views
Is there a way to access hard drives while computer sleeps?
Is there any way at all possible or possible with hardware (aside from a NAS) to access hard drives while the computer is in a low power mode such as sleep (aside from WOL)?
For example, can I log ...
0
votes
1answer
45 views
Diffie-Hellman and its disadvantage with large primes
I was reading our university slide on the Diffie-Hellman where it is mentioned that one of the disadvantages of D-H is that For large prime, $p-1$ is an even number so, $\mathbb{Z}^*_p$ will have a ...
0
votes
0answers
13 views
Given two or more nodes in a network, is it possible to determine the one-way link latencies between two nodes that share a bi-directional connection?
We already know that detecting the one-way latency between only two nodes is impossible.
However, if I have a number of nodes in the same subnet that all know about each other, can measure round-trip ...
2
votes
1answer
86 views
Two Generals Problems - What's wrong with my approach?
Some time ago, I've come across the Two Generals Problem and that it cannot be resolved. Now, recently, I've had an idea how to approach it. IMHO, it is a very obvious way to handle it but I haven't ...
0
votes
0answers
59 views
Calculation of total delay for multiple packets and multiple hops
I had this question on my homework for a class and don't understand the solution at all.
Assume there is no direct link between A and B. There exists one router C and two hops: Link A-C and link C-B....
0
votes
0answers
37 views
How TDM(TIme division multiplexing) affects bandwidth of the link and bandwidth of each station?
Sir
I have recently started studying computer networks. I have following doubt. Please clarify.
In TDM(Time division multiplexing), say we have broadcast link and N stations are connected to it. Then ...
0
votes
1answer
23 views
How can I download a streaming file without the file's specific address? [closed]
I want to download a streaming file, but I don't know the real address of that file, only the address where the stream is.
How can I download that file? Is it possible to know the address of the file ...
0
votes
0answers
8 views
What is the average time for a node to transmit on the shared medium for Ethernet? (IEEE 802.3)
Suppose a shared ethernet link L, in which for nodes T1-T4 and a router R are connected:
...
2
votes
2answers
2k views
How do web browsers find out the MAC address?
While reading through my textbook, I discovered that if you want to access a particular web page, your web browser will find out the IP address of the web server that hosts the web page and try and ...
1
vote
0answers
80 views
Bit stuffing in ethernet
I am naive to computer networks. I studied bit stuffing protocol which helps in identifying the end of the frame. If we assume a two systems which use ethernet protocol at data link layer. How the end ...
0
votes
0answers
11 views
Why not use a timer at sender instead of increasing transmision time in CSMA/CD to detect collisions?
In CSMA/CD protocol in order to detect collision Transmission time should be at least equal to two times 2×Tp, that means we have to change the frame size accordingly. Instead of all this why can't ...
0
votes
1answer
169 views
Calculate minimum and maximum Ethernet (IEEE 802.3) frame size from frame format
According the frame format of Ethernet
Minimum Frame Size should be :
7Bytes + 1Bytes + 6Bytes + 6Bytes + 2Bytes + 46Bytes +4Bytes = 72Bytes
Maximum Frame Size ...
0
votes
1answer
102 views
All-zeros subnet and All-ones subnet
It is said that practically all-zeros and all-ones subnets are not used.
Let us consider an a network $200.200.13.13/25$
Here Network ID is represented by using $25$ bits and Host ID using $32-25=7$ ...
0
votes
1answer
126 views
Hamming code distance and error detection
Suppose that data are transmitted in blocks of sizes 1000 bits. What is the maximum
error rate under which error detection and retransmission mechanism (1 parity bit per
block) is better than using ...
0
votes
1answer
28 views
IP addresses and CIDR suffixes
I'm somewhat confused about IP addresses and subnet masks.
Can a same IPv4 address have two different CIDR suffixes ?
for example 95.100.252.115/28 and 95.100.252.115/26 ?
If not, how is the CIDR ...
