在网线长度小于100米时,
Gigabit Ethernet 用cat5e与cat6区别不大。如果只在独立屋内布网,Gigabit switch/rouyer放地下室, 那么每根线的长度不会大于100米。
正如sip说的,cat5,cat5e,cat6,cat6a,cat7,cat7a网线都只用4根线。
Category 5 cable - Wikipedia, the free encyclopedia
Category 6 cable - Wikipedia, the free encyclopedia
Category 7 cable - Wikipedia, the free encyclopedia
8P8C - Wikipedia, the free encyclopedia
The
8 Position 8 Contact (
8P8C, also
backronymed as
8 position 8 conductor; it is often incorrectly called
RJ45)
[1] plugs and sockets are most regularly used as an
Ethernet connector.
[2] 8P8C connectors are typically used to
terminate twisted pair cable.
8P8C are commonly used in computer networking, where the plug on each end is an 8P8C modular plug wired according to a TIA/EIA standard. These cables are typically used to connect
Ethernet or
Token Ring network interfaces. Most network communications today are carried over
Category 5e or
Category 6 cable with an 8P8C modular plug crimped on each end.
The 8P8C modular connector is also used for
RS-232 serial interfaces according to the
EIA/TIA-561 standard
[1]. This application is commonly used as a console interface on network equipment such as
switches and
routers. Other applications include other
networking services such as
ISDN and
T1.
In floodwired
[3] environments the center (blue) pair is often used to carry
telephony signals. Where so wired, the physical layout of the 8P8C modular jack allows for the insertion of an
RJ11 plug in the center of the socket, provided the RJ11 plug is wired in true compliance with the U.S. telephony standards (RJ11) using the center pair. The formal approach to connect telephony equipment is the insertion of a type-approved converter.
The remaining (brown) pair is increasingly used for
Power over Ethernet (PoE). Legacy equipment may use just this pair; this conflicts with other equipment as manufacturers used to
short circuit unused pairs to reduce signal
crosstalk. Some routers/bridges/switches can be powered by the unused 4 lines — blues (+) and browns (−) — to carry current to the unit. There is now a standardized scheme for
Power over Ethernet.
Different manufacturers of 8P8C modular jacks arrange for the pins of the 8P8C modular connector socket to be linked to wire connectors (often IDC type terminals) that are in a different physical arrangement from that of other manufacturers: Thus, for example, if a technician is in the habit of connecting the white/orange wire to the "bottom right hand" IDC terminal, which links it to 8P8C modular connector pin 1, in jacks made by other manufacturers this terminal may instead connect to 8P8C modular connector pin 2 (or any other pin).