[SOLVED] Basic Question about Ethernet cable

[TheGreatPicazo]

Let´s say I have 4 PC's, and 3 of them are wireless conected to the internet, and the last one is not , so ,if I plug an ethernet cable into the 4th PC , how would the ethernet cable make my latency, download speed work? I mean, I know there's gonna be an improvement on the 4th PC but would the cable worsen the download speed, etc . on the other wireless conected PC's?

 

[bill001g]

Not directly because the wifi and ethernet have nothing to do with each other.

BUT for most people they still share the same internet bandwidth. This has nothing to do with ethernet vs wifi. All devices no matter how they are connected will compete for the internet. Depending on how large your internet connection is they may or may not have much impact on each other.

 

[TheGreatPicazo]

Not directly because the wifi and ethernet have nothing to do with each other.

BUT for most people they still share the same internet bandwidth. This has nothing to do with ethernet vs wifi. All devices no matter how they are connected will compete for the internet. Depending on how large your internet connection is they may or may not have much impact on each other.

But like, why are online games more playable through ethernet than wifi if all devices (no matter how they are connected ) are sharing the same bandwith?

 

[bill001g]

Mostly because in addition to sharing the internet bandwidth wifi is subject to interference from devices inside and outside the house. Wifi unlike ethernet attempts to do data recovery on damaged packetswhich causes delays.

Ethernet gets almost no packet corruption to start with and if it does it just discards the data which tends to work better for games than delays.

Still if someone is running huge downloads on a wifi connection and you have a small internet connection they will cause issues for a ethernet connected game.

 

[SamirD]

But like, why are online games more playable through ethernet than wifi if all devices (no matter how they are connected ) are sharing the same bandwith?

Two words--ping time.

Ping time is how fast a packet can get from your system to the destination and back to you. Wired local etherent will have ping times of less than 1 millisecond. Wired Internet will have ping times from a few milliseconds (really fast and high quality connections) to up to 100 milliseconds.

Wifi has longer ping times due to the correction of damaged packets, and even on the fastest of connections will still have a higher ping time than wired. Not only that, wifi doesn't scale well, so more traffic immediately makes the ping times increase substantially versus a comparable wired connection. Couple this with the up to 100 milliseconds pinging out to the Internet and a loaded wifi connection can have ping times of a couple of hundred milliseconds.

Now, the ping time is important for throughput because data is only received when it arrives properly. If it is damaged and has to be re-sent, that reduces throughput even though the bandwidth is there.

 

[beers]

Wifi unlike ethernet attempts to do data recovery on damaged packetswhich causes delays.

Incorrect, you're probably thinking about the CSMA/CA random backoff timer. 802.11 itself doesn't offer anything different than 802.3 as you still retain CRC and checksum data. At layer 2 the switch will simply drop a corrupted frame, it's up to a higher layer protocol like TCP to retransmit data. If wifi automatically retransmitted in the lower layer, it would be a terrible atrocity for any sort of real time UDP flows.

But like, why are online games more playable through ethernet than wifi if all devices (no matter how they are connected ) are sharing the same bandwith?

Wireless is a shared medium, and given the nature of RF, no two clients can broadcast on the same frequency at the exact same time (interference). Wi-Fi uses a collision avoidance mechanism where if the NIC sees something else broadcasting on that frequency, it will wait a random amount of time before trying again.

This is the primary contributor to wireless latency. It gets worse with more clients, and also other wifi and non-wifi interference. So if you have a bunch of consoles, IoT devices, tablets/phones and similar on the same frequency, your gaming packet may be waiting a while to be sent from the PC or sent from the router.

In a wired scenario they are packet switched, so everyone can talk at the same time and they don't have the same collision domain. You could recreate this in concept by using an old hub (not switch), as they have a shared collision domain. With a lot of wired clients your performance tanks similarly.

 

[bill001g]

Incorrect, you're probably thinking about the CSMA/CA random backoff timer. 802.11 itself doesn't offer anything different than 802.3 as you still retain CRC and checksum data. At layer 2 the switch will simply drop a corrupted frame, it's up to a higher layer protocol like TCP to retransmit data. If wifi automatically retransmitted in the lower layer, it would be a terrible atrocity for any sort of real time UDP flows.

You must not have every obtain any wifi certifications or you would know the details. The random backoff timer does make the problem worse but it is not the primary cause. Frames could be damaged by a baby monitor from the neighbors house that is not even running 802.11

It really doesn't matter why the checksums are bad the frame is still discarded. Both 802.3 and 802.11 discard the packet on the receiving end but the KEY difference is 802.11 REQUIRES frames be acknowledged. The sender when it does not receive a acknowledgment frame will re transmit the data some number of times until it does get acknowledged. What makes this even more complex is it could be the acknowledgement packet that is being damaged and discarded.

This is all done in the wifi radio chips with little to no ability to even detect it is being done. Very few wifi chipset even allow access to things like number of frames that had crc errors.

It is a "terrible atrocity" for UDP data streams and is why games are so greatly affected.