Ethernet Physical Layer PDF

Ethernet Physical Layer  Ethernet (IEEE 802.3)  Ethernet is a family of computer networking technologies for local area (LAN) and larger networks.  It was commercially introduced in 1980 while it was first standardized in 1983 as IEEE 802.3, and has since been refined to suppo...

Ethernet Physical Layer  Ethernet (IEEE 802.3)  Ethernet is a family of computer networking technologies for local area (LAN) and larger networks.  It was commercially introduced in 1980 while it was first standardized in 1983 as IEEE 802.3, and has since been refined to support higher bit rates and longer link distances.  Over time, Ethernet has largely replaced competing wired LAN technologies such as token ring, FDDI, and ARCNET.  The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet.  The original 10BASE5 Ethernet used coaxial cable as a shared medium.  Later the coaxial cables were replaced with twisted pair and fiber optic links in conjunction with hubs or switches.  Various standard defined for IEEE802.3 (Old Ethernet)  10Base5 -- thickwire coaxial  10Base2 -- thinwire coaxial or cheapernet  10BaseT -- twisted pair  10BaseF -- fiber optics  Fast Ethernet  100BaseTX and 100BaseF  Old Ethernet: CSMA/CD, Shared Media, and Half Duplex Links  Fast Ethernet: No CSMA/CD, Dedicated Media, and Full Duplex Links  Data rates have been incrementally increased from the original 10 megabits per second to 100 gigabits per second over its history.  Systems communicating over Ethernet divide a stream of data into shorter pieces called frames. Each frame contains source and destination addresses and error-checking data so that damaged data can be detected and re-transmitted.  As per the OSI model, Ethernet provides services up to and including the data link layer.  Evolution:  Shared media  Repeaters and hubs  Bridging and switching  Advanced networking  Varieties of Ethernet: Ethernet physical layer:   The Ethernet physical layer is the physical layer component of the Ethernet family of computer network standards.  The Ethernet physical layer evolved over a considerable time span and encompasses coaxial, twisted pair and fiber optic physical media interfaces and speeds from 10 Mbit to 100 Gbit.  The most common forms used are 10BASE-T, 100BASE-TX, and 1000BASE-T. They run at 10 Mbit/s, 100 Mbit/s, and 1 Gbit/s, respectively.  Fiber optic variants of Ethernet offer high performance, electrical isolation and distance (tens of kilometers with some versions).  Ethernet over twisted pair:  Ethernet over twisted pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network.  Early Ethernet cabling had generally been based on various grades of coaxial cable, but in 1984, StarLAN showed the potential of simple unshielded twisted pair by using Cat3 cable—the same simple cable used for telephone systems. This led to the development of 10BASE-T and its successors 100BASE-TX and 1000BASE-T, supporting speeds of 10, 100 and 1000 Mbit/s respectively.  Ethernet Media Standards and Distances: Details  There are single-mode optical fiber (SMF), laser optimized multi-mode optical fiber (MMF)  Multi-mode fibers are described using a system of classification determined by the ISO 11801 standard — OM1, OM2, and OM3. OM4 (defined in TIA-492-AAAD) was finalized in August 2009, and was published by the end of 2009 by the Telecommunications Industry Association (TIA). The letters "OM" stand for optical multi-mode.  The main difference between multi-mode and single-mode optical fiber is that the former has much larger core diameter, typically 50–100 micrometers.  Multi-mode fibers are described by their core and cladding diameters. Thus, 62.5/125 µm multi-mode fiber has a core size of 62.5 micrometres (µm) and a cladding diameter of 125 µm.  62.5/125 µm (OM1) and conventional 50/125 µm multi-mode fiber (OM2) were widely deployed in premises applications. These fibers easily support applications ranging from Ethernet (10 Mbit/s) to gigabit Ethernet (1 Gbit/s).  Optical fiber manufacturers have greatly refined their manufacturing process to offer higher bandwidths (data rates). Hence, newer deployments often use laser-optimized 50/125 µm multi-mode fiber (OM3) and 50/125 µm multi-mode fiber (OM4, higher bandwidth). These fibers easily support applications ranging from 10 gigabit Ethernet to 100 gigabit Ethernet.  100-gigabit Ethernet (100GbE) and 40-gigabit Ethernet (40GbE) are groups of computer networking technologies for transmitting Ethernet frames at rates of 100 and 40  gigabits per second (100 to 40 Gbit/s), respectively. The technology was first defined by the IEEE 802.3ba-2010 standard.  The industry has widely adopted the terms short reach, long reach and extended reach to match 10GBASE-SR, 10GBASE-LR, and 10GBASE-ER respectively. From an IEEE standards perspective, the “S” represents the 850 nm Short wavelength, the “L” stands for the 1310 nm Long wavelength, and the “E” stands for the 1550 nm Extra long wavelength. 100G Port Types:  100GBASE-CR10: 100GBASE-CR10 ("copper", 10m) is a port type for twin-ax copper cable. It uses ten lanes of twin-ax cable delivering serialized data at a rate of 10.3125 Gbit/s per lane.  100GBASE-CR4: 100GBASE-CR4 ("copper", 10m) is a port type for twin-ax copper cable. It uses four lanes of twin-ax cable delivering serialized data at a rate of 25.78125 Gbit/s per lane.  100GBASE-SR10: 100GBASE-SR10 ("short range", OM3 MMF cable: 100m, OM4 MMF cable: 150m) is a port type for multi-mode fiber and uses 850 nm lasers. It uses ten lanes of multi-mode fiber delivering serialized data at a rate of 10.3125 Gbit/s per lane.  100GBASE-SR4: 100GBASE-SR4 ("short range", OM3 MMF cable: 100m, OM4 MMF cable: 150m) is a port type for multi-mode fiber and uses 850 nm lasers. It uses four lanes of multi-mode fiber delivering serialized data at a rate of 25.78125 Gbit/s per lane.  100GBASE-LR4: 100GBASE-LR4 ("long range", 10 km) is a port type for single-mode fiber and uses four lasers using four wavelengths around 1310 nm. Each wavelength carries data at a rate of 25.78125 Gbit/s.  100GBASE-ER4: 100GBASE-ER4 ("extended range", 40km) is a port type for single- mode fiber and uses four lasers using four wavelengths around 1550 nm. Each wavelength carries data at a rate of 25.78125 Gbit/s. 40G Port Types  40GBASE-CR4: 40GBASE-CR4 ("copper", 10m) is a port type for twin-ax copper cable. It uses four lanes of twin-ax cable delivering serialized data at a rate of 10.3125 Gbit/s per lane.  40GBASE-SR4: 40GBASE-SR4 ("short range", OM3 MMF cable: 100m, OM4 MMF cable: 150m) is a port type for multi-mode fiber and uses 850 nm lasers. It uses four lanes of multi-mode fiber delivering serialized data at a rate of 10.3125 Gbit/s per lane.  40GBASE-LR4: 40GBASE-LR4 ("long range", 10 km) is a port type for single-mode fiber and uses 1310 nm lasers. It uses four wavelengths delivering serialized data at a rate of 10.3125 Gbit/s per wavelength.  40GBASE-ER4: 40GBASE-ER4 ("extended range", 40km) is a port type for single-mode fiber being defined in P802.3bm and uses 1550 nm lasers. It uses four wavelengths delivering serialized data at a rate of 10.3125 Gbit/s per wavelength.  40GBASE-FR: 40GBASE-FR is a port type for single-mode fiber (10km). It uses 1550 nm optics, has a reach of 10 km and is capable of receiving 1550 nm and 1310 nm wavelengths of light. 1550 nm was chosen as the wavelength transmission to make it compatible with existing test equipment and infrastructure.  40GBASE-T: 40GBASE-T (100m) is a port type for 4-pair balanced twisted-pair Cat.8 copper cabling being defined in P802.3bq.