CCNA1_M7_Ethernet_Technologies (1130701)

Просмтор этого файла доступен только зарегистрированным пользователям. Но у нас супер быстрая регистрация: достаточно только электронной почты!

Текст из файла

CCNA – Semester1Module 7Ethernet TechnologiesObjectives• Ethernet relevant issues• 10 Mbps and 100 Mbps• 1000 Mbps and Gigabit Ethernet10-Mbps and 100-MbpsEthernetType of Ethernet• All version of Ethernet have the same:– MAC addressing– CSMA/CD– Frame format• However, other aspect of MAC sublayer, physical layerand medium have changed.Parameters for 10Mbps EthernetLine Encoding• All 10 Mbps forms of Ethernet take octetsreceived from the MAC sublayer and perform aprocess called line encoding.• Line encoding describes how the bits areactually signaled on the wire.• The form of encoding used in 10 Mbps systemsis called “Manchester”.Manchester Encoding10BASE-T Wiring and Architecture• 10BASE-T links generally consist of a connectionbetween the station and a hub or switch.• The most important aspect to consider for 10BASET architecture is minimizing the delay betweendistant stations100-Mbps Ethernet•••100 Mbps Ethernet is also known as Fast Ethernet.The two technologies that became important are 100BASE-TX,which is copper UTP based, and 100BASE-FX, which ismultimode optical fiber based.Three characteristics common to 100BASE-TX and 100BASEFX are:– timing parameters– the frame format– parts of the transmission process.100Mbps Ethernet Encoding• The higher frequencysignals are moresusceptible to noise.• Two encoding steps for100-Mbps Ethernet.– 4B/5B– actual line encoding specificto copper or fiber.100BASE-TX• 100BASE-TX can be either full-duplex or half-duplex• Ethernet network use separate transmit and receive wirepairs (full-duplex) and a switched topology preventscollisions on the physical bus.• 100BASE-TX uses 4B/5B encoding, which is thenscrambled and converted to multilevel transmit-3 levelsor MLT-3.100BASE-FX• A fiber version desired for backbone connections aswell as those between floors and buildings wherecopper is less desirable, and also in high noiseenvironments• Gigabit Ethernet standards are now the dominanttechnology for backbone installations, high-speedcross-connects, and general infrastructure needs.NRZI Encoding• 100BASE-FX uses 4B/5B encoding, which isthen scrambled and converted to nonreturn-zero-inverse or NRZI.Class of Repeater• A Class I repeater may introduce up to 140 bittimes of latency.

Any repeater that changesbetween one Ethernet implementation andanother is a Class I repeater.• A Class II repeater may only introduce amaximum of 92 bit-times latency. Because of thereduced latency it is possible to have two ClassII repeaters in series, but only if the cablebetween them is very short.Gigabit and 10-Gigabit Ethernet1000 Mbps Ethernet• The 1000 Mbps Ethernet or Gigabit Ethernetstandards represent transmission using bothfiber and copper media.• The 1000BASE-X standard (IEEE 802.3z)specifies a 1-Gbps full duplex over opticalfiber.• The 1000BASE-T standard (IEEE 802.3ab)uses a media of Category 5e or higher UTP.• 1000BASE-TX, 1000BASE-SX, and1000BASE-LX use the same timingparameters.Gigabit Ethernet Encoding• The shorter duration bit times require GigabitEthernet to use two separate encoding steps.• At the physical layer, the bit patterns from theMAC layer are converted into symbols.• Fiber-based Gigabit Ethernet (1000BASE-X)uses 8B/10B, followed by the simple Non-Returnto Zero (NRZ) line encoding of light on opticalfiber.Actual 1000BaseT Signal Transmission• Cat 5e cable can reliably carryup to 125 Mbps of traffic.1000BASE-T uses all four pairsof wires.• The circuitry has to divideframes at the transmitter andreassemble them at the receiver.• For 1000BASE-T 4D-PAM5 lineencoding is used on Cat 5e orbetter UTP.

The actualtransmitted signal in eachdirection on each wire pair is a 5level {+2, +1, 0, -1, -2} pulse1000BASE-SX and LX• 1000BASE-X uses 8B/10B encoding converted to nonreturn to zero (NRZ) line encodingMedia Access Control• The Media Access Control method treats the link aspoint-to-point. Since separate fibers are used fortransmitting (Tx) and receiving (Rx) the connection isinherently full duplex.• Gigabit Ethernet permits only a single repeater betweentwo stations.1000Mbps Ethernet• 1000BASE-SX use short-wavelength by 850 nm laseror LED source in multimode optical fiber.• 1000BASE-LX use long-wavelength by 1310 nm lasersource uses either single-mode or multimode opticalfiberGigabit Ethernet Architecture• Daisy-chaining, star, and extended startopologies are all allowed.• The bandwidth of fiber is inherently verylarge.

It has been limited by:– emitter technology– fiber manufacturing processes– detector technology10 Gigabit Ethernet• IEEE 802.3ae was adapted to include 10-Gbps fullduplex transmission over fiber-optic cable.• With single-mode fiber, the maximum transmissiondistance is 40 kilometers makes 10GbE a viable MANtechnology .• Compatibility with SONET/SDH networks operatingup to OC-192 speeds (9.584640 Gbps) make 10GbE aviable WAN technology.• Some discussions between IEEE members havebegun that suggest the possibility of standards for40-, 80-, and even 100-Gbps Ethernet.Parameters for 10GbE Operation802.3ae June 2002 10GbE family.• 10GBASE-SR –short distances, multimode fiber, rangebetween 26 m to 82 m• 10GBASE-LX4 – wavelength division multiplexing(WDM), supports 240 m to 300 m over multimode fiberand 10 km over single-mode fiber• 10GBASE-LR and 10GBASE-ER – support 10 km and 40km over single-mode fiber• 10GBASE-SW, 10GBASE-LW, and 10GBASE-EW –workwith OC-192 synchronous transport module (STM)SONET/SDH WAN equipment.Future of Ethernet• Ethernet has gone through an evolution from Legacy→ Fast → Gigabit → MultiGigabit technologies.• The future of networking media is three-fold:– Copper (up to 1000 Mbps, perhaps more)– Wireless (approaching 100 Mbps, perhaps more)– Optical fiber (currently at 10,000 Mbps and soon to be more)Summary• 10Base2, 10Base5, 10BaseT• Line encoding: Manchester, MTL3, NRZI…• Characteristics and varieties of 100-MbpsEthernet• Characteristics and varieties of 1000-MbpsEthernet• Basic architectural considerations of Gigabitand 10-Gigabit Ethernet.

Характеристики

Тип файла PDF

PDF-формат наиболее широко используется для просмотра любого типа файлов на любом устройстве. В него можно сохранить документ, таблицы, презентацию, текст, чертежи, вычисления, графики и всё остальное, что можно показать на экране любого устройства. Именно его лучше всего использовать для печати.

Например, если Вам нужно распечатать чертёж из автокада, Вы сохраните чертёж на флешку, но будет ли автокад в пункте печати? А если будет, то нужная версия с нужными библиотеками? Именно для этого и нужен формат PDF - в нём точно будет показано верно вне зависимости от того, в какой программе создали PDF-файл и есть ли нужная программа для его просмотра.

Список файлов учебной работы