Sự khác nhau giữa FastEthernet 100BaseTX và 100BaseT4?

[tuaninbox]

Các anh có thể cho em biết sự khác nhau giữa fastethernet 100BaseTX và 100BaseT4. Thực tế bên ngoài mình sử dụng loại nào? Có yêu cầu gì đặc biệt về cable khi sử dụng không?

Thanks

[Neo]

Hi, nội dung này anh có thể tìm đọc trong quyển Cisco LAN Switching - Kennedy Clark

Cheers,

[Neo]

Sau đây là một trích đoạn:

100BaseTX

Many existing 10 Mbps twisted-pair systems use a cabling infrastructure based upon Category 5 (unshielded twisted-pair) UTP and (shielded twisted-pair) STP. The devices use two pairs of the cable: one pair on pins 1 and 2 for transmit and one pair on pins 3 and 6 for receive and collision detection. 100BaseTX also uses this infrastructure. Your existing Category 5 cabling for 10BaseT should support 100BaseTX, which also implies that 100BaseTX works up to 100 meters, the
same as 10BaseT. 100BaseTX uses an encoding scheme like Fiber Distributed Data Interface (FDDI) of 4B/5B. This encoding scheme adds a fifth bit for every four bits of user data. That means there is a 25 percent overhead in the transmission to support the encoding. Although 100BaseTX carries 100 Mbps of
user data, it actually operates at 125 Megabaud. (We try not to tell this to marketing folks so that they do not put on their data sheets 125 Mbps throughput!)

100BaseT4

Not all building infrastructures use Category 5 cable. Some use Category 3. Category 3 cable was installed in many locations to support voice transmission and is frequently referred to as voice grade cable. It is tested for voice and low speed data applications up to 16 MHz. Category 5 cable, on the other hand, is intended for data applications and is tested at 100 MHz. Because Category 3 cable exists in so many installations, and because many 10BaseT installations are on Category 3 cable, the IEEE 802.3u committee included this as an option. As with 10BaseT,
100BaseT4 links work up to 100 meters. To support the higher data rates, though, 100BaseT4 uses more cable pairs. Three pairs support transmission and one pair supports collision detection. Another technology aspect to support the high data rates over a lower bandwidth cable comes from the encoding technique used for 100BaseT4. 100BaseT4 uses an encoding method of 8B/6T (8 bits/6 ternary signals) which significantly lowers the signaling frequency, making it suitable for voice-grade wire.

[nguyenhungvuong]

Oh,

tai lieu nay hay qua,

cam on pac Neo nhieu.

theo ly thuyet cua tai lieu, thi cap CAT5e tro len co the tuong thich nguoc cho tat ca cac ung dung truoc do.

cho minh hoi tham ban tuaninbox, ung dung 100Base-T4 do ban su dung cho ung dung gi, va thiet bi no ra sao?

ve phan cap chuan cho Ethernet 10Base-T, 100 Base-TX, 1000Base-T, 1000 Base-TX thi minh ranh, chu 100Base-T4 thi minh chua tung duoc so mo gi ca,

cheer.

nguyenhungvuong.