This article organizes several terms commonly used in early home Internet access: broadband, narrowband, ADSL, PPPoE, virtual dial-up, modem, and router. Naming conventions vary across eras and service providers, but the relationships among these concepts are generally as follows: ADSL is an access-line technology, PPPoE is an authentication and session protocol, a modem handles line-signal conversion, and a router shares the connection and forwards data.
Ways to Get Online
Common access methods can be divided into the following categories:
- Using a 56K modem to dial up over a telephone line.
- Using an ADSL broadband line, connecting through an external ADSL modem, and then dialing from a computer or router.
- Using a router or local area network to access an existing network.
- Using a wireless network card to connect to a Wi-Fi network.
- Using a mobile phone to get online, including using the phone as a modem for dial-up, accessing mobile data networks such as GPRS, or directly using the phone's own network connection.
Ways for a Laptop to Get Online
Common ways for a laptop computer to access the Internet include:
- Connecting a telephone line to the laptop's built-in modem for traditional telephone dial-up access.
- Connecting a network cable to the laptop and obtaining a network connection through an ADSL modem, optical modem, router, or local area network.
- Accessing the network through a router or local area network.
- Opening wireless network settings and connecting to Wi-Fi.
- Using a mobile phone, data cable, and corresponding drivers to use the phone as a mobile network access device.
ADSL (Broadband)
ADSL stands for Asymmetric Digital Subscriber Line. In Chinese, it is usually translated as “非对称数字用户线路” or “非对称数字用户环路.” It uses ordinary telephone lines to transmit digital data and designs upstream and downstream bandwidth asymmetrically: download speed is usually higher than upload speed.
ADSL itself is an access-line technology. A user typically needs an external ADSL modem at home, which converts the DSL signal on the telephone line into an Ethernet signal that a computer or router can use. The “broadband account” and “broadband password” provided by the carrier are usually not part of the ADSL line itself, but account information used later for PPPoE authentication.
PPPoE (Virtual Dial-up)
PPPoE stands for Point-to-Point Protocol over Ethernet. It is commonly used for broadband access authentication: the user enters the account and password provided by the carrier, the device establishes a session through PPPoE, and after successful authentication it obtains a network connection.
In early Windows systems, this type of connection was often called a “broadband connection” or “virtual dial-up.” It looks like dial-up, but it is not the same as a traditional 56K modem dialing a telephone number. Instead, it establishes a logical connection over an existing Ethernet link.
ADSL Virtual Dial-up
So-called ADSL virtual dial-up means that when using ADSL to access the Internet, the user still needs to enter a username and password, which is similar to earlier modem or ISDN dial-up access. But an ADSL connection does not dial a specific access phone number, such as 16900. Instead, it initiates authentication with the carrier's access server through PPPoE or a similar method, and after successful authentication it obtains an IP address and joins the network.
Two common home network configurations are:
- Computer dial-up: the telephone line connects to the ADSL modem, the modem then connects to the computer with a network cable, and the “broadband connection” on the computer is used to enter the account and password and dial.
- Router dial-up: the telephone line connects to the ADSL modem, the modem connects to the router's WAN port, and the router stores the broadband account and password and dials automatically, allowing multiple devices to share the network through the router.
If the router handles dialing, the computer usually does not need to click “broadband connection” separately. If both the computer and router dial at the same time, the connection may fail or the account may conflict.
56K Modem (Narrowband)
Although broadband later became increasingly common, in suburban areas or small towns where broadband had not yet been enabled, a 56K modem was once still one of the options for getting online.
A 56K modem is a device that connects a computer to another computer or a computer network through a telephone line. Its role is to modulate the computer's digital signals into analog signals that can be transmitted over a telephone line and then passed through the network to another computer or server. For received analog signals, it demodulates them into digital signals so the computer can recognize them.
In addition, some modems also have fax capabilities and can be used to receive and send faxes. Some models also have voice capabilities, enabling functions such as voicemail.
56K refers to the theoretical speed when the modem establishes a network connection with the ISP. In actual use, because telephone line quality, line distance, and network congestion vary, the transmission rate often fails to reach the rated value: under good conditions it may approach 52K, while in remote areas it may be only 14K to 36K. Therefore, a 56K modem is already inadequate for most modern Internet applications.
Suitable users: people who already have a modem, such as a laptop's built-in modem, and only need occasional Internet access. One could also buy a new modem or find a second-hand “cat” to use, with generally low investment.
In the past, when using a 56K modem to get online, in addition to cheap monthly plans, public general-purpose accounts and passwords were also common, such as account 16300 and password 16300. This meant that even when traveling with a laptop, as long as a small hotel had a telephone line, temporary Internet access might be possible for receiving email, checking QQ messages, and so on.
Modem (Cat, Modulator-Demodulator)
Modem is the English name for “调制解调器,” commonly nicknamed “cat” in Chinese. It is a type of hardware device whose main function is to convert between different types of line signals and digital signals that a computer can process.
It is important to note that a traditional telephone modem built into a laptop is generally used for 56K telephone dial-up and cannot directly replace an ADSL modem for ADSL virtual dial-up. When using ADSL, an external ADSL modem is usually required; when using fiber broadband, a similar access conversion task is usually handled by an optical modem.
Router
A router is responsible for forwarding data between different networks. In home broadband, it usually handles several common functions:
- Storing the broadband account and password through PPPoE and automatically completing ADSL virtual dial-up.
- Sharing one carrier broadband connection with multiple computers, phones, or other devices.
- Providing wired LAN ports and wireless Wi-Fi.
- Performing home-network functions such as NAT, DHCP assignment, and basic firewalling.
A typical home network can use a “modem or optical modem + router” structure for access. It is also possible to connect another router behind one router, but in that case attention must be paid to WAN/LAN wiring, whether DHCP is duplicated, whether double NAT is created, and similar issues. For ordinary home use, the simplest approach is usually to let one main router handle dialing and address assignment, while other devices are used as switches or wireless extenders.