Do you use ADSL? Learn about the real speed of ADSL
1,512k ADSL mean?
512K = 512kbps = 512k bits / s = 64K bytes / s
I think this will have no problem.
What does 2,64k bytes / s mean?
The true meaning of this 64K is "the biggest download bandwidth that individual users can enjoy"
So what does this mean? I don't know if there is anyone who has noticed the application form for Telecom ADSL installation. The above bandwidth project writes "no higher than 512K", "no higher than 8m", etc., that is, Say that we can have up to 64k-have-bandwidth in normal cases.
Note that it is "not higher than", then it means many times our proprietary bandwidth may be less than 64K, is it why?
In fact, China Telecom's ADSL is running on the ATM, and the ATM to the chinanet edge router bandwidth is 155m, and each edge router can connect to 3000 users. If these users are simultaneously online, then each user is only 50k bit / s bandwidth, That is, 7k bytes / s, plus the router attenuation, then eventually only the speed of ordinary Modem.
Of course, the above is only imaginary. After all, 3,000 people are almost impossible over one edge router. Telecom does not make the router full-load connection and make the speed fall so.
However, 64K is the highest proprietary bandwidth is unquestionable.
3, why can my 512K ADSL often reach the speed of 100k or even 200K?
We figured out that 64K is the largest exertion wide, but not equal to the maximum bandwidth. In fact, the actual approximately 8Mbps is already allocated at the ADSL dial, which is 1M Bytes / S download bandwidth, but telecommunications limits our proprietary The bandwidth is up to 64K, then when the router is connected to the user, we can get a part of the shared bandwidth that exceeds the proprietary bandwidth (obviously telecom is not necessary to idle these bandwidth), of course, the 512K rate ADSL will never achieve shared bandwidth The download speed of 1m / s, because there is always a lot of people in the same time after all, and Telecom has some balanced load mechanism.
4, the impact of ADSL upload speed on download
TCP / IP regulations, each package requires the backhabilization of the ACKNOWLEDGE message, that is, the information transmitted, you need to have a message reply that receives the information, in order to determine whether the back transfer speed and decide whether to re-transfer data.
A part of the uplink is used to transmit these Acknowledge (confirm) information. When the uplink load is too large, it will affect the speed of the ACKNOWLEDGE data, and then affect the download speed. This is especially obvious that the asymmetric digital loop is also the connection of the ADSL's uplink bandwidth far less than the download bandwidth.
There is a test prove that when the upload is fully loaded, the download speed is changed to 40% of the ideal speed, which can explain why many friends
A slightly speed limit can be obtained with BT download.
In this case, we can't ask all people to be unmarried, because this is very unrealistic for ADSL users, and is not scientific. The appropriate speed limit is correct.
5, the speed of ADSL gradually decreases as the connection time is extended.
The highest theoretical 8Mbps download bandwidth will be established when I say ADSL and then dial, this bandwidth will never change! However, due to the noise detection mechanism of ADSL If the line situation is not good, the connection established is clearly impossible to achieve the theoretical value, it may eventually be 5Mbps, this bandwidth will not change.
So why said the speed of ADSL is getting slower and slower?
This is because even if the user does not close the power supply of the modem, sometimes the ADSL link will be interrupted at any time. For example, in the case where the communication status is deteriorated due to the increase in noise, there is frequent errors. After the link is interrupted, you will immediately re-debug and re-determine the link. However, if the noise of the link interrupt still exists at this time, (this is generally a relatively large) re-linking speed will be lower than the original. Since the link speed determined in debug is also fixed, even after the noise disappears, the link speed will not increase. The longer the ADSL modem usage time, the higher the possibility of this situation, so the connection speed is getting slower. At this time, if the user restarts the modem, the link will reiterate and the speed may result in an increase. This common sense can be used as a process countermeasure after the link speed is reduced.
Of course, these situations are only discussed according to the ADSL connection itself, and the actual situation also includes Internet conditions, the response of the website itself, etc.
Understand the above knowledge, you may suddenly be clear. It turns out that 512K is not 512KB, only 64kb, 呜 ~~~ You can't reach 512KB download speed per second.
