I. What is the Difference Between Bandwidth and Broadband?
- Bandwidth is a quantifier referring to the size of the internet speed. For example, 1Mbps means one megabit per second, which is the value indicating bandwidth.
- Broadband is a noun describing a network with high transmission rates. The standards for broadband vary. Initially, anything above 128kbps was considered broadband, while anything below was considered narrowband.
- Currently, domestic operators typically provide broadband services with at least 512kbps bandwidth. In other words, bandwidth is a specific numerical value, while broadband is a transmission standard (service) that meets a certain bandwidth value.
Broadband: In digital communication, it usually refers to a bandwidth above 64kbit/s.
Narrowband: In digital communication, it usually refers to a bandwidth below 64kbit/s.
1. Broadband
When someone asks if you can access the internet at home, they are essentially asking if you have broadband. Broadband is a noun; the term "bandwidth" comes after "broadband" and is not directly related to the speed of internet access.
2. Bandwidth
When applying for broadband, you need to register with service providers, who offer different packages with options like 10Mb/s, 20Mb/s, etc. You can calculate your bandwidth using the byte conversion ratio:
- 1B = 8b (1 byte = 8 bits)
- 1KB = 1024B
- 1MB = 1024KB
- 1GB = 1024MB
For example, if you apply for a 10Mb/s bandwidth, the "b" in the unit is lowercase. Since 1B (byte) = 8b (bits), the download speed is: 10Mb / 8 = 1.25MB.
Why divide by 8?
In computers, download speed is measured in bytes (B), while service providers quote speeds in bits (b).
For instance, when downloading a software online, the size is given in bytes (B). Similarly, when opening a webpage with images, text, and videos, these contents are essentially downloaded to your computer before you can view them.
You can calculate your download speed using bandwidth:
| Bandwidth | Download Speed | Formula |
|---|---|---|
| 2Mb | 256KB/s | 2 / 8 = 0.25 |
| 4Mb | 512KB/s | 4 / 8 = 0.5 |
| 8Mb | 1.00MB/s | 8 / 8 = 1.0 |
| 10Mb | 1.25MB/s | 10 / 8 = 1.25 |
| 20Mb | 2.50MB/s | 20 / 8 = 2.50 |
| 100Mb | 12.5MB/s | 100 / 8 = 12.50 |
Sometimes, software tests may show slightly different speeds due to physical line wear and other objective factors.
3. Traffic
Traffic refers to the total size of data sent and received, measured in 1024-based units: B, KB, MB (M), GB (G).
- 1G = 1024MB
- 1M = 1024KB
- 1KB = 1024 bytes (B)
For example, a mobile data plan might offer 5 yuan for 30MB or 10 yuan for 70MB. Opening a webpage with 100 Chinese characters and a 100KB image would consume:
- 100 * 2B / 1024 + 100KB = 0.2KB + 100KB = 100.2KB
Visiting this page once generates 100.2KB of traffic. With a 70MB plan, browsing a few pages quickly depletes the data, let alone watching videos.
II. Relationship Between Bandwidth, Internet Speed, and Traffic
For example:
- My home bandwidth is 10M.
- Current internet speed: 200KB/s.
- Viewing an image uses 8M of traffic.
1. Bandwidth Unit: bits per second (bps): 10M = 10Mbps
2. Internet Speed Unit: bytes per second (B/s, KB/s, MB/s)
3. Traffic Unit: bytes (Byte)
Conversion: Bandwidth size / 8
- 10M bandwidth (10Mb/s) = 1.25MB/s internet speed
- 1M bandwidth (1Mb/s) = 0.125MB/s = 128KB/s
- 10Mbps = 101024Kbps = 1010241024bps = 101024*1024/8 Byte/s = 10/8 MB/s = 1.25 MB/s
III. What are Upstream and Downstream Bandwidth? What are their Functions?
Upstream and downstream bandwidth, or upstream and downstream speed, refer to:
When accessing the internet, there are two actions: uploading data and downloading data. Upstream broadband (speed) refers to the upload speed, while downstream broadband (speed) refers to the download speed.
Upstream Bandwidth (Upstream Rate):
Generally refers to the upload speed from your computer, the rate at which others communicate with your computer. For example, uploading photos to QQ Space.
Downstream Bandwidth (Downstream Rate):
Generally refers to the download speed from the internet to your computer, such as downloading files or opening web pages.
Upstream and downstream speeds are usually asymmetric, with downstream speed being greater than upstream speed.
IV. Understanding Server Upstream and Downstream Bandwidth
For servers, client downloads consume the server's upstream traffic, and client uploads consume the server's downstream traffic.
Server Upstream Bandwidth:
Used for local users requesting resources from the server (maximum data transfer per second from the server to the client).
Server Downstream Bandwidth:
Used for local users uploading files to the server. Downstream bandwidth for servers is usually unlimited, depending on the client's network conditions.
V. Differences Between Intranet IP and Public IP
Intranet IP:
Assigned by the router within a local network, unique within the local network but not outside.
Public IP:
Assigned by the internet service provider, unique globally.
Key Points:
- Public IPs are globally unique, while intranet IPs are unique only within the local network.
- All computers in a local network share the same public IP.
- Each computer in a local network can assign its own IP, valid only within the local network.
- Public IP addresses are managed by IANA.
- There are also secondary NET technologies, meaning your campus gateway might also be a local network.
Practical Tips:
- Most ADSL bandwidths before upgrading to large bandwidths are dynamic public IPs. Upgrading to 100M fiber usually results in a private IP.
- Most proxy network operators provide private IPs.
- Most fiber internet connections provide private IPs.
Visual Method:
The following IP ranges are private IPs:
- 10.0.0.0 to 10.255.255.255
- 172.16.0.0 to 172.31.255.255
- 192.168.0.0 to 192.168.255.255