Maison > Article > base de données > 当前各种接入网技术(Access Network technologies)
1. Dial-Up Back in the 1990s, almost all residential users accessed the Internet over ordinary analog telephone lines using a dial-up modem. The term dial-up is employed because the user's software actually dials an ISP's phone number and
1. Dial-Up
Back in the 1990s, almost all residential users accessed the Internet over ordinary analog telephone lines using a dial-up modem.
The term "dial-up" is employed because the user's software actually dials an ISP's phone number and makes a traditional phone connection with the ISP. As shown in following picture.
Dial-Up Internet access
2. DSL
Today the two most prevalent types of broadband residential access are digital subscriber line(DSL) and cable.
DSL Internet Access
3. Cable
Many residences in the North America and elsewhere receive hundreds of broadcast television channels over coaxial cable networks.
Cable Internet access makes use the cable television company's existing cable television infrastructure. A residence obtains cable Internet access from the same company that provides it cable television. as the following Figure.
A hybrid fiber-coaxial access network
4. Fiber-To-The-Home(FTTH)
Fiber optics can offer significantly higher transmission rates than twisted-pair copper wire or coaxial cable.
Some local telcos(in many different countries), having recently laid optical fiber from their COs to homes, now
provide high-speed Internet access as well as traditional phone and television services over the optical fibers.
The following figure shows FTTH using the PON distribution architecture. Each home has an optical network terminator(ONT),
which is connected by dedicated optical fiber to a neighborhood splitter, the splitter combines a number of homes ont o a single,
shared optical fiber, whichi connects to an optical line terminator(OLT) in the telco's CO. The OLT, providing conversion between
optical and electrical signals, connects to the Internet via a telco router.
In the home, users connect a home router(typically a wireless routor) to the ONT and access the Internet via this home router.
In the PON architecture, all packets sent from OLT to the splitter are replicated at the splitter(similar to a cable head end).
FTTH Internal Access
Ethernet Internal Access
来自“Computer Networking:A top to down approach”