Common network transmission media has the following four types:
(1) Twisted pair (2) Coaxial cable (3) Optical cable (optical fiber) (4) Wireless communication (microwave / satellite communication) WAN has the following: 1, public telephone network (PSTN -PUBLIC SWITHED Televhone Network) Speed 9600bps ~ 28.8kbps, required
To be asynchronous MODEM and telephone line, less investment, installation and commissioning is easy, often used as a dial-up access method. Usually, we visited i
NTERNET uses this approach.
2, the basic interface of the ISDN-ITEGRATED Service Digital Network 128kbps
, Use ordinary telephone lines but require telecommunications to provide ISDN services, digital transmission, caller ID, short time short (3S), fees
It is 4 times that of ordinary calls. There are still not many cities that are currently ISDN.
3, DDN Line: Speed is 64kbps ~ 2.048Mbps (E1 standard), you need to match synchronous modem,
There are two standards of EIA / TIA 232 (V.24) and V.35; point-to-point connection, the structure is not flexible enough. 4,
