Questions tagged [computer-networks]

Questions about problems that arise when you connect multiple computers to form a network.

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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 ...
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Migrate from win server 2008 r2 to 2016 server [on hold]

I inherited a small customer with a Dell T110 server with Windows server 2008 r2 foundation that has programs that came preinstalled as a package. It is currently configured with RAID 1. This server ...
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43 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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24 views

Computing effective transfer speed [Effective Transmission rate?]

A) Given 10 Mb/s network through three store-and-forward switches with frame size of 5000 bits and length of ACK frames of ...
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37 views

Construction of Omega Network

I understand that we could draw N * N Omega Network, But can we draw an Omega Network to connect 6 CPUs to 4 memories? (The number of CPUs does not equal the number of memories)
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26 views

Confused between bandwidth and frequency

I am new to Computer Science and started learning about computer networking very recently. I know that bandwidth means how many bits can be sent through the channel in 1 second. However, recently I ...
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14 views

Why should a potential drawback of layering be that functionality at one layer may need information that is present only in another layer?

Protocol layering has conceptual and structural advantages [RFC 3439]. As we have seen, layering provides a structured way to discuss system components. Modularity makes it easier to update system ...
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7 views

maximal number of time slots until a successful transmission in adaptive tree walking protocol

i have a problem understanding some vital points in adaptive tree walking protocol: for simplicity sake, only two stations want to broadcast in the given network: A and C. what is the maximal number ...
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1answer
22 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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35 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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9 views

minimal broadcasting frame length in a CSMA/CD protocol

i'm unsure about the following question, would appreciate your assistance with it: in a CSMA/CD network with a cable length of L, and propagation speed T, with no need of repeaters(the signal is not ...
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8 views

theoretical question about difference between transmitting stations in Bit-Map Protocol

i am wondering about the difference between the transmitting station in a bit map protocol. for instance, if we have 8 broadcasting stations numbered 0-7, and the racing (contenting) time is $t_0$ ...
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24 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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18 views

go back n protocol scenario consequences

i am not sure with tihs question. i will post it here along with my attempt: the following scenario is regarding go back protocol n, with 3 bits for sequential numbering, assuming that the following ...
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54 views

finding the overhead and distance of an unknown code based on message making algorithm

for an information word M with m bits that is coded as following: M is coded into a word A using an unknown code that allows detection of not more than one error. the code word is the word obtained ...
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18 views

Calculating p-persistent CSMA Network probability

Let's say that, in a p-persistant CSMA network one station, X, is ready to transmit data. All other stations are idle for 5 time slots after X has become ready. What is the probability that X ...
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15 views

Finding current levels when encoding information in a channel

I am stuck with the following question: In a noised channel with a bandwidth of 4 kHz that has the signal-noise ratio of 30 decibels, if it is known that the maximal broadcasting speed is 16000 bps,...
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14 views

Maximal number of parallel cellular calls with no adjacent cells in a hexagonal setting

Is it possible to find an optimization to the following theoretical case? Given is a cellular (phone) system with hexagonal cells, where the volume of transmission and the size of the cells are ...
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22 views

A file is sent from host A to client B, the packet passes through router R on its way to B. Calculate the total delay for the file to reach B

This is a question from an old exam that ive been trying to work out: The 40000 bit file is split into 10 packets with a 400 bit header added to each packet The link from A to R is 500 km long and ...
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1answer
63 views

Network throughput with random delay selected from uniform distribution

Background: I am working with IoT devices which broadcast status messages over a wireless channel periodically and at a rather high rate (500-5000 Hz). Receiving every message is not crucial but the ...
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10 views

Networks-on-Chip : separable allocator VS wavefront allocator

How is separable allocator different from wavefront allocator ? See page 86 and 87 of On-Chip Networks, Second Edition Synthesis Lectures on Computer Architecture
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Application deployement and network models [closed]

I am a self-taught in computer science. I am interested on have a robust test book on which study the nut and bolt of application deployment. I mean all the processes involved in getting new software ...
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1answer
13 views

Maximum number of nodes connected when the link has a large buffer

A link of capacity 100 Mbps is carrying traffic from a number of sources. Each source generates an on-off traffic stream;when the source is on, the rate of traffic is 10 Mbps, and when the source is ...
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23 views

What is the name of the domain or theoretical problem of transmitting game states in an online game

For example, in chess (or any online game), you broadcast the game state to other players at certain times (every n-milliseconds or after a move is made). Thereupon, a player's game client renders the ...
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15 views

transmit delay end to end

If PC1 divided the original packet (1.5 MB) to three equal packets (each packet is the length of 512 KB), then how much time is needed to transmit the 3 packets back-to-back. how can i solve this ...
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93 views

Efficiency of UDP protocol

When 54 bytes of data is transferred using the UDP protocol, the efficiency is? (In per cent) IN UDP, the maximum datagram size can be $2^{16}-1 \, bytes$ Now to this, 8 Bytes of UDP header is ...
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27 views

Why does packet delivery time only count transmission time once?

Why is packet delivery time equal to transmission time + propagation delay, and not equal to 2*(transmission time) + propagation delay? At the end of packet delivery time, doesn't that mean that ...
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2answers
55 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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25 views

Stop and Wait Efficiency

A sender uses Stop and Wait protocol for transmission of 8000K bits size frames on a 1Gbps satellite channel with a propagation delay of $400ms$.What will be the link utilization(in percent),if ...
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39 views

Computer Networks, bandwidth calculation

I don't know if this is the right place to ask this kind of questions, but I'm a little desperate and I can't find the answer to this Computer Networks exam question. "A point to point 1000 km ...
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37 views

Understanding acknowledgement mechanism in sliding window protocol

I came across following problem: Node A sends packets to B through router R. The link A-R is instantaneous , but the R->B link transmits only 1 packet each second , one at a time . Assume A sends ...
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What are the things one can do with the internet without the World Wide Web? [closed]

If the question above makes any sense!
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148 views

Exercise: Sliding window protocol: Bits for sequence number

This is a task in a lecture on computer networks: "Suppose you are designing a sliding window protocol for a 1-Mbps point-to-point link to the moon, which has a one-way latency of 1.25 seconds. ...
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1answer
81 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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Wifi throughput calculation

I have a problem which i don't know how to calculate or more specifically what am I missing. The subject is about 802.11 (wifi) The selected PHY rate is 54Mbit/s, that is whenever DATA is being sent ...
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38 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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304 views

What exactly is transmission time?

Seems very trivial but I'm confused which one of these correctly define transmission time. Time taken by a message to reach receiver. Time taken to push message on the link by the sender. Which ...
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1answer
82 views

Stop and Wait retransmission of packets?

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 I ...
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257 views

The min number of distinct sequence numbers required to ensure correct operation of the ARQ scheme is

In a sliding window ARQ scheme, the transmitter's window size is N and the receiver's window size is M. The minimum number of distinct sequence numbers required to ensure correct operation of the ARQ ...
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1answer
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Anonymous Visibility Check in P2P networks

I'm working on a problem for a P2P network for games. The problem is the following: Consider two opponents on a grid, each stores it's own position. Player 1 wants to know if it sees player 2. In ...
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41 views

why not just one header in TCP/IP?

I was reading through the computer network fundamentals. I noticed that there are headers added at each layer in the OSI model. However, can we not have just one header above the App layer that ...
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2answers
28 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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63 views

Paxos Consensus

how does Paxos Consensus algorithm behave in an asynchronous environment? Because as far as I know Paxos only work in synchronous environment. Correct me if I am wrong :) Sorry for the noob question,...
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1answer
56 views

How can average queuing delay exceed 1 if the $La/R \leq 1$?

Consider a router with a packet arrival rate of $a$ where each packet has $L$ bits, and a transmission rate (in bits/s) of $R$. My textbook describes the traffic intensity as $\frac{La}{R}$ and states ...
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126 views

What will happen if congestion window size touches to zero in congestion control mechanisms in TCP?

Folowing is the Congestion Control Window graph of TCP. What will happen if Congestion Window reaches to zero when timeout occurs ?
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18 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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Local to global algorithms in gossip based P2P networks

Suppose we have a peer to peer network of, say, $n$ peers. Peers communicate by an asynchronous randomized gossip protocol (Push, Pull, Push/Pull doesn't really matter here). The task is for any local ...
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2answers
391 views

Does UDP always deliver packets inorder to the application layer

I was reading about UDP and TCP. TCP is a stream-oriented, connection-oriented protocol and always delivers the segments in order to the application layer. But UDP being connectionless, does it also ...
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94 views

IP Address CIDR Bitmask Conversion

In looking for a programming function to validate an IP address within a subnet, I had to calculate the subnet mask from a given CIDR bitmask value ie. 192.168.0.0/24, the value 24 in this example. ...
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1answer
59 views

How to distinguish between bits?

I read a post about differences between synchronous and asynchronous transmission modes. That post has a picture about how bits flows from terminal to computer in async mode. But how computer can ...