tailieunhanh - Ethernet Networking- P3

Ethernet Networking- P3:One of the biggest problems when discussing networking is knowing where to start. The subject of computer networks is one of those areas for which you have to "know everything to do anything." Usually, the easiest way to ease into the topic is to begin with some basic networking terminology and then look at exactly what it means when we use the word Ethernet. | 48 Fast and Gigabit Ethernet Media and Standards attenuation. Fiber optic media can therefore be used in situations where wire media pose problems such as on factory floors. It is much harder for someone to tap than wire media. It is much less susceptible to attenuation than wire media. It has much higher bandwidth than most wire media. The same fiber optic media can carry Ethernet signals at any standard speed. On the other hand fiber optic cabling is more difficult to work with than wire. It cannot be spliced and taped with electrical tape like wire but instead requires special connectors that precisely line up the ends of two segments of cable with one another. In addition fiber optic equipment is more expensive than equipment for wire media. Nonetheless in environments where many devices share network media in particular linking servers or where severe electrical interference is a factor fiber optic cabling is a viable choice. For example in graphics and video design firms where large files move between workstations fiber optic cabling can significantly speed up workflow by providing additional bandwidth. Single versus Multimode Fiber Optics There are two types of fiber optic cabling single mode and multimode. Single mode which can transmit a single wavelength of light long distances is used primarily for WAN connections. Multimode can transmit multiple signals at one tim but is more limited in length and typically used in LANs. When light is introduced into an optical fiber it can either go straight down the middle of the optical tube or it can travel at an angle reflecting off the side of the tube as it travels. Each signal traveling down the tube at a time is known as a mode. The diameter of the core of a single-mode fiber is very small for example 9 microns . A single ray of light is transmitted down the core and it travels without reflection straight to its destination. In theory one single-mode fiber link can be as long as 10 kilometers. Fiber Optic .