Signal leaves the NIC and enters the cable on the Orange pair. White- Orange is +ve, solid Orange is negative. Signal leaves the cable and enters the NIC on the SPLIT Green pair. White- Green is +ve, solid Green is negative. 568 B 7.1.4 10BASE-T
However, other aspects of the MAC sublayer, physical layer, and medium have changed.
802.2 Fast Ethernet 7.1 10-Mbps and 100-Mbps Ethernet 100
7.1.6 100-Mbps Ethernet The only difference between Ethernet and Fast Ethernet is the Bit Time The two technologies that have become important are 100BASE-TX, which is a copper UTP medium and 100BASE-FX, which is a multimode optical fiber medium.
7.1.6 100-Mbps Ethernet The 100-Mbps frame format is the same as the 10-Mbps frame.
These higher frequency signals are more susceptible to noise.
In response to these issues, two separate encoding steps are used by 100-Mbps Ethernet.
The first part of the encoding uses a technique called 4B/5B
The second part of the encoding is the actual line encoding specific to copper or fiber.
The data byte to be sent is first broken into two nibbles.
If the byte is 0E, the first nibble is 0 and the second nibble is E.
Next each nibble is remapped according to the 4B5B table.
Hex 0 is remapped to the 4B5B code 11110.
Hex E is remapped to the 4B5B code 11100.
In 100BASE-FX and 100BASE-TX, the 4B5B replacement happens at the Physical Coding Sub-layer (PCS)
Information is then further encoded for transmission using
MLT-3 in 100BASE-TX at the Physical Medium Dependent (PMD) sub-layer
NRZI in 100BASE-FX at the Physical Media Attachment (PMA) sub-layer
There will always be at least one ‘1’ in each byte, eliminating long strings of zeros. MULTI-LEVEL TRANSMIT 11101 1111 F 11100 1110 E 11011 1101 D ... ... ... 10100 0010 2 01001 0001 1 11110 0000 0 4B5B Code (Binary) Data (Hex) 4B5B Encoding Table
7.1.7 100BASE-TX multi-level transmit-3 levels 100BASE-TX (like 100BASE-FX) uses 4B/5B encoding which is then scrambled and converted to multi-level transmit-3 levels or MLT-3. Any Transition = binary 1. No transition = binary 0. Long strings of zeros would give a ‘DC’ component but because of the 4B/5B encoding this can never happen.
100BASE-TX can be either full-duplex or half-duplex
An Ethernet network using separate transmit and receive wire pairs (full-duplex) and a switched topology prevents collisions on the physical bus.
7.1.8 100BASE-FX 100BASE-FX (like 100BASE-TX) uses 4B/5B encoding which is then scrambled and converted to Non Return to Zero, Inverted . Non Return to Zero, Inverted Any Transition = binary 1. No transition = binary 0. Long strings of zeros would give a ‘DC’ component but because of the 4B/5B encoding this can never happen. Fiber cannot use the 3 level MLT3 because the light source has only two levels, ON and OFF.
7.1.8 100BASE-FX 200 Mbps transmission is possible because of the separate Transmit and Receive paths in 100BASE-FX optical fiber.
The main application for which 100BASE-FX was designed was inter-building backbone connectivity
100BASE-FX was never adopted successfully. This was due to the timely introduction of Gigabit Ethernet copper and fiber standards.
Gigabit Ethernet standards are now the dominant technology for backbone installations, high-speed cross-connects, and general infrastructure needs .
The introduction of switches has made this distance limitation less important.
If workstations are located within 100 m of a switch, the 100 m distance starts over at the switch.
Since most Fast Ethernet is switched, these are the practical limits between devices.
A Class I repeater may introduce up to 140 bit-times of latency. Any repeater that changes between one Ethernet implementation and another is a Class I repeater. A Class II repeater may only introduce a maximum of 92 bit-times latency.
Every ten bit code group must fit into one of the following three possibilities:
Six ones and four zeros
Five ones and five zeros
Four ones and six zeros
This helps limit the number of consecutive ones and zeros between any two code groups.
flip 110000 0101 001111 1010 101 11100 D28.5 same 001110 1010 001110 1010 101 11100 D28.5 flip 001010 1001 110101 1001 001 00100 D4.1 same 100010 1011 011101 0100 000 00001 D1.0 Effect on RD after Sending RD+ Encoding Value RD- Encoding Value Actual Byte Being Encoded Code Group Name
10GBASE-SR – Intended for short distances over already-installed multimode fiber, supports a range between 26 m to 82 m
10GBASE-LX4 – Uses wavelength division multiplexing (WDM), supports 240 m to 300 m over already-installed multimode fiber and 10 km over single-mode fiber
10GBASE-LR and 10GBASE-ER – Support 10 km and 40 km over single-mode fiber
10GBASE-SW, 10GBASE-LW, and 10GBASE-EW – Known collectively as 10GBASE-W are intended to work with OC-192 synchronous transport module (STM) SONET/SDH WAN equipment.
Physical Media Dependent Each transceiver has four 3.125-Gbit/s DFB lasers that are optically multiplexed to provide a 10-Gbit/s data throughput. 10GBASE-LX4 uses Wide Wavelength Division Multiplex (WWDM) to multiplex four bit simultaneous bit streams as four wavelengths of light launched into the fiber at one time. Physical Media Attachment