1. What is the difference between bandwidth and broadband?
Bandwidth is a quantifier that refers to the size of the network speed, for example, 1Mbps means one megabit per second, and this value refers to the bandwidth.
Broadband is a noun that indicates that the transmission rate of the network is very high. Broadband standards vary, but it was initially thought that bandwidth above 128kbps was wideband, while below narrowband was considered.
However, domestic carriers generally provide broadband services with a bandwidth of at least 512kbps. In other words, bandwidth is a specific value, and broadband is a transmission standard (service) that satisfies a certain bandwidth value.
That is, broadband is a kind of service, and bandwidth is the transmission speed.
- Broadband: In digital communication, it usually refers to the bandwidth of a signal above 64 kbit/s.
- Narrowband: In digital communication, it usually refers to the bandwidth of a signal below 64 kbit/s.
1. Broadband
In fact, this means whether your home has broadband, in other words, it is a noun, first with the word broadband, and then you can say how much bandwidth you have, and broadband is not directly related to the speed of Internet access.
2. Bandwidth
When we want to apply for broadband, we need to register with some service providers, at this time, depending on the package, you may have 10Mb/s, 20Mb/s, etc., and you can calculate your bandwidth size by converting computer bytes
Like what:
1B=8b //1字节=8位
1KB=1024B
1MB=1024KB
1GB=1024MB The bandwidth we applied for is 10Mb/s, and the b in this unit is lowercase, and the 1B (bytes) = 8b (bits) we just said here is exactly 8 times the relationship, that is, the download speed: 10Mb/8 = 1.25MB
Some people will ask, why divide by 8?
In a computer, the download speed is measured in bytes (B), while the provider says it is measured in bits (b).
For example, if you download a piece of software on the Internet, it will be measured in B (bytes), and if you open a web page, there may be pictures, text, videos and other content in this web page, which is essentially downloaded to your computer and then you can see it.
We can calculate our own download speed with bandwidth:
Calculation method: bandwidth size / 8
| bandwidth | Download speed | official |
| The bandwidth is 2Mb | The download speed is 256KB/s | 2 / 8 = 0.25 |
| The bandwidth is 4Mb | The download speed is 512KB/s | 4 / 8 = 0.5 |
| The bandwidth is 8Mb | 下载速度为1.00MB/s | 8 / 8= 1.0 |
| The bandwidth is 10Mb | 下载速度为1.25MB/s | 10 / 8 = 1.25 |
| The bandwidth is 20Mb | 下载速度为2.50MB/s | 20 / 8 = 2.50 |
| The bandwidth is 100Mb | 下载速度为12.5MB/s | 100 / 8 = 12.50 |
Sometimes, when using some software to test the network speed, we find that there is a little gap with our calculated results, which is a normal phenomenon, which is caused by objective reasons such as the wear and tear of some physical lines.
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Sometimes, when you download software in the middle of the night, you will find that the download speed exceeds the value we have calculated theoretically, and this situation also exists
We can understand it like this: For example, if your home is in Zone J, then the bus line from the provider to Zone J is 100Mb/s, and your home is 10M, because the restrictions are set from the router, this is related to the settings of the router.
The second situation is that the server where you download the software is relatively idle, so the speed is also relatively fast
The third situation is that when we download the software, we may use the software in this area, because there are more people who download this software, then his speed is also relatively fast.
In layman's terms:
Bandwidth is like the size of your faucet, and the speed of your internet is like how fast the water flows out of the faucet.
The above is all about the download speed, so how is the upload speed calculated, in fact, the upload speed is different from the region, and the general upload speed is limited by the provider, which is not accurate.
3. Flow rate
Traffic is the sum of the size of the outgoing data and the received data packets, and the unit is in 1024 base system, and the units are B, KB, MB (M), GB (G)
1G=1024MB
1M=1024KB
1KB=1024字节(B） Generally, our mobile phones have 5 yuan 30MB, 10 yuan 70MB data package, when we open a web page, how much traffic do we need?
Suppose there are 100 Chinese characters and a 100KB image on a web page, and one Chinese character = 2 bytes
That is, the data size of this page is: 100 * 2B / 1024 + 100KB = 0.2KB + 100KB = 100.2KB;
Every time you visit this page, you will generate 100.2KB of traffic, and if it is 70MB of traffic, then you will almost run out of several web pages, let alone watch videos.
2. The relationship between bandwidth, network speed, and traffic
Usually: we say
我家的带宽10M
现在网速网速：200KB/s
看一张图片使用了8M的流量 So what is the relationship between bandwidth, network speed, and traffic, and what do they represent?
1. The bandwidth unit is: bits per second (bps): 10Mbit/s=10Mbps
2、网速是数据传输的速度，单位是：字节/秒 (B/s， KB/s， MB/s)
1MB/s=1024KB/s
1KB/s=1024B/s 3. Traffic is the sum of the amount of data sent and received by the user on the Internet, and the unit is: byte;
A bit is the smallest unit of information: 1 byte = 8 bits, which is 1B = 8 bits or 1B = 8b
1 byte/sec=8 bits/sec (1B/s=8bps)
1 bit (1b or 1 bit) is the smallest unit of storage in information technology, and one bit represents a "1" or "0";
1B (1 byte) is a relatively small storage unit: in general, one English letter occupies one byte, and one Chinese character occupies two bytes.
4. Conversion between them: bandwidth size / 8
10M带宽(10Mb/s)=1.25MB/s网速
1M带宽(1Mb/s)=0.125MB/s=128KB/s
10Mbps = 10*1024Kbps =10*1024*1024bps =10*1024*1024/8 Byte/s =10/8 MB/s =1.25 MB/s 3. What do upstream bandwidth and downstream bandwidth mean, and what are their functions?
What do you mean by upstream bandwidth and downstream bandwidth, or upstream speed and downstream speed?
When setting the speed limit of the router, or configuring some other software, you will encounter the configuration of the uplink speed and downlink speed, many users do not know what these two represent, and the following will explain these two in detail:
There are two behaviors when accessing the internet: one is to upload data and the other is to download data. Uplink bandwidth (speed) refers to the speed at which the data is uploaded, while downlink bandwidth (speed) refers to the number of degrees at which data is downloaded.
In detail, it can be understood as:
The uplink bandwidth is the uplink rate
Generally refers to the speed at which it is uploaded from your computer, and the rate at which others communicate with your computer. For example, if you upload your photos to QQ space, the speed of uploading photos at this time is the uplink speed, and other examples, when you upload files to some cloud disks, the speed at this time is also the uplink rate, and we may find that under normal circumstances, the speed of uploading files is much slower than the network speed we usually use.
Downlink bandwidth is the downlink rate
Generally it is the speed at which you download from the host on the network, such as the speed at which you download files, the speed at which you open web pages, this speed is the downlink rate, and the downlink rate is usually what we usually call the network speed, for example, your bandwidth is 8M for telecommunications, 20M for optical fiber, etc., this speed is actually the downlink rate of the network.
The uplink broadband (speed) and downlink broadband (speed) are asymmetrical.
Generally, the downward speed is greater than the upward speed. The amount of bandwidth we usually use refers to the downlink broadband, because we mainly download data from the Internet, and the amount of data uploaded is much less.
Why is it that in the process of using broadband, I find that the download speed of the computer does not meet the standard of my own broadband, such as 10Mb/s broadband, and the download speed is only about 1MB/s, why is this?
The unit of the downlink speed of the bandwidth of a broadband operator is different from that of a Windows computer, the unit of a Windows computer is KBbs/s, while the unit of broadband operation is Kbbs/s, 1B = 8b (1 byte = 8 bits).
Suppose you have 10M broadband, 10Mbps = 10240Kbps/8 = 1280KBps, so the maximum download speed on your computer is only 1280KBps, which is about 1.25MB/s. So don't say that the broadband company cheats people and handles the broadband deduction, which is just caused by the different units of calculation.
In addition to the broadband bandwidth, the download rate of broadband is related to the computer configuration, the download software used, the size of the download, the speed of the download website, etc., and the broadband download rate (such as Thunderbolt) that can be viewed by the general download software.
Ideally: the downlink bandwidth of 100M fiber broadband is between 10M/s and 11M/s; uplink broadband refers to the speed of uploading to the Internet; the broadband you want to open is the same or not the uplink and downlink; if you don't know, you can consult your operator; if it is equivalent, your uplink broadband is also between 10M/s and 11M/s; if it is not equivalent, the general uplink broadband is only 400kbs/s-500Kbs/s.
Note: Generally, the uplink and downlink bandwidth of the enterprise is the same, and the household is not the same, and generally only the downlink bandwidth is managed, and the uplink is not concerned.
4. Understanding of the server's upstream and downstream bandwidth
For the server, the client downloads resources and consumes the server's upstream traffic, and the client uploads resources to consume the server's downstream traffic.
For servers that are usually bought, such as Alibaba Cloud, the bandwidth generally purchased refers to the uplink bandwidth, and the downlink is usually unlimited. And the calculation of the flow rate is generally calculated from the upper line.
Therefore, when the client uploads resources, it basically has no impact on the bandwidth of the server, because the downlink of the server is basically unlimited, which has an impact on the bandwidth of the client's own network.
The client downloads resources, in addition to the bandwidth of the server, and the network bandwidth of the client itself.
The upstream bandwidth of the server
The uplink bandwidth of the server is mainly used for local users to request resources on the server (the maximum amount of data transmitted by the server to the client per second, the bandwidth outgoing from the server) (i.e., local download, server upload)', if the files on the server are downloaded on other machines, the uplink bandwidth of the server is mainly used.
Here we must distinguish between the upstream bandwidth and the downstream bandwidth, and the download speed of the personal PC depends on the downstream bandwidth of the server and the upstream bandwidth of the server
The personal PC (A) is connected to the server (B), and the maximum uplink bandwidth (uplink speed) of server B determines the maximum download speed of the PC.
The downstream bandwidth of the server
The downlink bandwidth is mainly used for local users to upload files to the server (the customer uploads data to the server), for the server, the downlink bandwidth is unlimited, and the network factor depends on the current network situation of the client
5. Differences between intranet IP and extranet IPs
distinguish
As shown in the figure, suppose our computer is device one and wants to access Baidu.
If you want to use the campus network, you first need to convert our internal IP address to the external IP address of the campus network through the router of the campus network.
Then through this external network IP, first connect to the gateway of Hunan Telecom, and finally connect to the gateway of Baidu.
Baidu sends the information you requested back to your campus network gateway, which in turn sends the information to you (the entire network has a mesh structure, and it will automatically find a path to Baidu - based on depth-first search or breadth-first search).
This process is similar to Taobao shopping.
Suppose you order a book at school, Taobao receives your order and prepares the items and starts shipping them to you.
He found that your delivery address was in Hunan, so it may have started from Hangzhou, first went to the transfer station in Fujian, and then to the transfer station in Jiangxi, and suddenly found that the transfer station from Jiangxi to Hunan was not passable, so it could only go around to the transfer station in Guangdong, and finally to the transfer station in Hunan. These transit stations are equivalent to gateways on the public network.
When you arrive at the Hunan transit station, the courier brother will deliver the package to your school gate (this is the last level of gateway).
At this time, the courier brother left, and the administrator at the school gate took the package to you according to your dormitory information. (Information exchange within the LAN is handled by the gateway of the campus network)
This is a little difficult for people who are new to the Internet to understand the difference between intranet IP and public IP, so let's take an example
We compare the 201 room of the hotel to the intranet IP, then any hotel may have 201 rooms, if you are hungry will say to the waiter: "I am in room 201, please send some food". And if you order takeout, you only say to the store to send room 201 (intranet IP), it is impossible for people outside to know, then you have to say to the store that a certain hotel in a certain district of a certain city (public IP) plus a 201 room can find you.
- The public IP address assigned by the operator (a hotel in a certain district of a certain city) is the hotel where it stays, and room 201 (intranet IP) is assigned by the hotel housekeeper (router). So a hotel can have a lot of rooms (intranet IP), but when a friend outside asks you where you live, you will definitely not say that you live in room 201 (intranet IP), but will say that you live in a certain hotel (public IP) in a certain district of such and such a city.
This is the essential difference between private IP addresses and public IP addresses. One internal, one external
Attention
1. The public IP is unique in the world, while the private IP is only unique within the LAN
2. The intranet IPs of all computers in a LAN are different from each other, but they share an external IP.
Just like the hotel example: your school has only one name in the world, but classroom 3 on the 3rd floor of Building A in your school is only unique within your campus. Other schools also have classroom No. 3 on the 3rd floor of Building A. You can only say to the courier brother please help me deliver the package to xx university, but you can't say please help me deliver the package to classroom 3 on the 3rd floor of Building A.
3. In the LAN, each computer can assign its own IP, but this IP is only valid in the LAN. And if you connect your computer to the Internet, your network provider's server will assign you an IP address, which is your IP address on the Internet. Two IPs exist at the same time, one internally and one externally.
4. The IP address on the Internet (i.e., the Internet IP) address is managed by an organization called "ANA". Due to the unreasonable allocation and the limitations of the IPv4 protocol itself, the IP address resources of the Internet are becoming more and more strained. IANA reserves a portion of Class A, B, and C IP addresses for use on a local area network. The details are as follows
IP address space:
a类网
10.0.0.0 ~ 10.255.255.255
b类网
172.16.0.0 ~ 172.31.255.255
c类网
192.168.0. 0~ 192.168.255.255 In other words, if the IP address you find is within the range of the above A, B, and C IP addresses, it must be the IP address of the local area network, otherwise it is the address of the public network.
5. In real life, there are not only first-level NET technology, but also second-level NET technology. That is, it is possible that your campus gateway is only a local area network. More addresses can be obtained through multi-level conversion.
1. Empirical method
1. Generally, the ADSL bandwidth of telecom is a (dynamic) public IP before the large bandwidth is upgraded. If it costs very little money to upgrade you to 100M fiber optic Internet access, 99.99% is an intranet IP, then 0.01% is a case that I have not found yet.
2. 99.99% of proxy network operators are intranet IPs, such as Great Wall Bandwidth, Juyou E-home, etc.
3. 99.99% of optical fiber Internet access is intranet IP.
2. Intuitive method
The addresses in the following CIDR blocks are private IP addresses
10.0.0.0 到 10.255.255.255172.16.0.0 到172.31.255.255192.168.0.0 到192.168.255.255 ---END---