querierd | little background on IP
kandi X-RAY | querierd Summary
kandi X-RAY | querierd Summary
To explain the problem we need a little background on IP multicasting and IGMP snooping. Multicasting was designed for delivering high-bandwidth data streams, TV in other words, across a network without overloading the network. If an internet TV station had to send its video stream to each subscriber individually, the outgoing network link from the station would have to carry many, many identical data streams. There is no way that they could possibly get enough bandwidth. And anyway it is silly to send many copies of the same stream. Multicasting avoids this problem by providing a way for a single stream to be delivered to many subscribers. The outgoing stream is directed to a single multicast address belonging to a "multicast group". When a router receives the packets of such a stream on an upstream port, it sends a copy to each of its downstream ports provided that some downstream node on that port has joined the multicast group. How does it know whether any downstream nodes belong to the group? That job is handled by the IGMP protocol. But the bandwidth problem is not limited to routers. It also occurs with swithes on a local area network, especially when wireless is involved. If one person on your LAN is watching TV on their iPad, connected to a wireless access point which is connected to one port of your DNS or cable router, then your router needs to deliver the stream to the WAP. But the WAP is most likely behaving as a switch, not a router. So it is not supposed to be interpreting packets, just forwarding them to the devices connected to it. If this rule were followed strictly, it would mean that any device connected to that WAP would receive the video stream, even if it is not watching TV. And that video stream uses a substantial portion of the bandwidth available on the wireless link. So innocent devices who are not watching TV would experience a significant slowdown. To deal with this problem, switches use IGMP snooping. See the wikipedia article. The idea of IGMP snooping is that a switch will watch the IGMP traffic generated by the devices it serves in order to decide which multicast groups each device wants to belong to. The switch then notifies its upstream router that it wants to subscribe to all groups which have at least one member among the nodes served by the switch. If no device on a switch port wants to belong to a certain group, then the switch will not forward any multicast packets for that group. A key point is this: while IGMP v2 provides a way for a device to leave a group, the switch cannot count on a device sending a leave request. First of all, the leave requests did not exist in IGMP v1, which the device may be using. Secondly, the device might crash. Therefore, a switch which does IGMP snooping will set an "IGMP membership timeout." When a device subscribes to a multicast group it must renew its membership before the timeout expires; otherwise the switch will mark it as not belonging to the group and stop sending it packets for that group. But, you ask, what does this have to do with avahi or bonjour? Well, it turns out that those protocols also use multicasting. There is a multicast group for mDNS (the address is 224.0.0.251). All of the communication related to avahi or bonjour uses multicast packets sent to this multicast group. So now we see the problem. The avahi or bonjour daemon on your device joins the mDNS multicast group when it starts up. But it is not the job of the avahi-daemon to ensure that your device remains a member of the mDNS group. That job is supposed to be handled automatically by the switches and routers on your network, using IGMP. The reason your device disappears after a while is that a switch, probably your WAP, does not hear any subsequent IGMP join requests from your device. So, after a while, the switch stops forwarding any mDNS packets, and the device "disappears".
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Top functions reviewed by kandi - BETA
- Start querier
- Returns the elapsed time in seconds
- Listen for incoming packets
- Converts an address into an integer
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Trending Discussions on Utilities
QUESTION
I've been upgrading my CRA project to TailwindCSS 3, but now CSS nesting no longer works. Upon starting the server, the console spits out:
...ANSWER
Answered 2022-Feb-03 at 18:38This is mostly just bad news.
Create React App's Tailwind support means that they will detect tailwind.config.js in the project and add tailwindcss to their existing postcss configuration. Source in CRA
The guide that Tailwind offers on their site creates a dummy postcss.config.js - Making changes in this file does not change the actual postcss configuration. (misleading if anything)
This is a known issue currently - Github discussion on Tailwind support PR between Adam Wathan (Tailwind founder) and Ian Sutherland (CRA maintainer). But it does not seem like there is an intention to be fixed soon.
If you want to use nesting (or any PostCSS plugin really) is to eject from CRA using:
QUESTION
I'm attempting to create an apollo client plugin for a Nuxt 3 application. It's currently throwing an error regarding a package called ts-invariant:
ANSWER
Answered 2022-Jan-07 at 01:52Solved by including @apollo/client and ts-invariant/process into the nuxt build transpile like so:
QUESTION
Very first try on Nuxt3 via Nuxt3 Starter
I wonder how can I use tailwindcss in Nuxt3 Starter manually.
(Not via @nuxtjs/tailwindcss , because it's for Nuxt2, and not work with Nuxt3.)
I created a blank Nuxt3 project by
...ANSWER
Answered 2021-Oct-04 at 04:17Maybe your problem is because you need a tailwindcss.config.js.
For this, simply type in the console:
QUESTION
In a fresh Laravel 9 installation, the URL processing from Laravel Mix does not work anymore.
npm outputs the following:
...ANSWER
Answered 2022-Feb-22 at 10:55Actually moving the css imports into resources/js/app.js solves this problem. However, this results in the imported css to be included in the public/js/app.js, not the public/css/app.css.
QUESTION
I'm trying the create a 3D subscene with objects being labelled using Label objects in a 2D overlay. I've seen similar questions to mine on this subject, and they all point to using the Node.localToScene method on the node to be labelled in the 3D space. But this doesn't seem to work for my case. I've taken example code from the FXyz FloatingLabels example here:
The Label objects need to have their positions updated as the 3D scene in modified, which I've done but when I print out the coordinates returned by the Node.localToScene method, they're much too large to be within the application scene, and so the labels are never visible in the scene. I've written an example program that illustrates the issue, set up very similarly to the FXyz sample code but I've created an extra SubScene object to hold the 2D and 3D SubScene objects in order to plant them into a larger application window with slider controls. The 3D scene uses a perspective camera and shows a large sphere with coloured spheres along the x/y/z axes, and some extra little nubs on the surface for reference:
...ANSWER
Answered 2022-Feb-02 at 12:28If you follow what has been done in the link you have posted you'll make it work.
For starters, there is one subScene, not two.
So I've removed these lines:
QUESTION
I am new to angular and was following the documentation to build a basic app.
Node - v14.7.3
npm - 7.22.0
Angular CLI: 12.2.4
OS: win32 x64
@angular-devkit/architect 0.1202.4
@angular-devkit/build-angular 12.2.4
@angular-devkit/core 12.2.4
@angular-devkit/schematics 12.2.4
@schematics/angular 12.2.4
rxjs 6.6.7
typescript 4.3.5
So far all I have done is
npm install @angular/cli
followed by ng new firstApp
and ng serve
Following is the error that I am receiving,
...ANSWER
Answered 2021-Sep-10 at 07:17Try to install those modules separately npm install:
QUESTION
I've installed tailwind using npm install tailwindcss
I then create my src/style.css file and include
ANSWER
Answered 2021-Dec-25 at 20:47You need to add a config js file for the tailwind engine, inside the config file use content attribute to define where is your HTML or JS files, the new engine automatically looks inside these files and compiles only the classes that you used.
Check this video for more information:https://youtu.be/mSC6GwizOag?t=22
QUESTION
I am testing a library like follows:
...ANSWER
Answered 2022-Jan-20 at 14:01Here's the equivalent C++20 code to your first version of FromDateTime:
QUESTION
I'm looking for ways to count the number of trailing newlines from possibly binary data either:
- read from standard input
- or already in a shell variable (then of course the "binary" excludes at least 0x0) using POSIX or coreutils utilities or maybe Perl.
This should work without temporary files or FIFOs.
When the input is in a shell variable, I already have the following (possibly ugly but) working solution:
...ANSWER
Answered 2022-Jan-18 at 13:29Using GNU awk for RT and without reading all of the input into memory at once:
QUESTION
I want to create dark mode for a web site which use bootstrap. I have to add new root class which includes all boostrap colors. Here is my colors.scss:
...ANSWER
Answered 2021-Aug-07 at 20:32As explained here, there's no way to attach a class to :root. However, you don't need this to achieve what you want.
Simply make a dark class then you can add that as desired to the html or body tag.
Make all the needed theme color changes inside .dark{}, and then @import "bootstrap". When .dark doesn't exist on the body, the theme colors will return to Bootstrap defaults.
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Install querierd
There are two steps to installing QuerierD. First you need to install a python package named querier, as well as the package netifaces, which QuerierD uses. If you have python setuptools installed, then the command. should install both packages, as needed. (Note, however, that installing netifaces may require a C compiler.) If you don't have setuptools you will need to install netifaces separately. Step 1 may or may not require superuser permissions, depending on how your python installation is configured.
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