CCNA1 M7 Ethernet Technologies

8/14/2019 CCNA1 M7 Ethernet Technologies

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CCNA Semester1

Module 7

Et hernet Tec hnolog ies

Objectives

Ethernet relevant issues 10 Mbps and 100 Mbps

1000 Mbps and Gigabit Ethernet


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10-Mbps and 100-Mbps

Ethernet

Type 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.


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Parameters for 10Mbps Ethernet

Line Encoding

All 10 Mbps forms of Ethernet take octetsreceived from the MAC sublayer and perform a

process 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.


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Manchester Encoding

10BASE-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 10BASE-T architecture is minimizing the delay between

distant stations


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100-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 is

multimode optical fiber based.

Three characteristics common to 100BASE-TX and 100BASE-FX are:

timing parameters

the frame format

parts of the transmission process.

100Mbps Ethernet Encoding

The higher frequencysignals are more

susceptible to noise.

Two encoding steps for

100-Mbps Ethernet. 4B/5B

actual line encoding specificto copper or fiber.


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100BASE-TX

100BASE-TX can be eitherfull-duplex orhalf-duplex

Ethernet network use separate transmit and receive wirepairs (full-duplex) and a switched topology prevents

collisions on the physical bus.

100BASE-TX uses 4B/5B encoding, which is thenscrambled and converted to multilevel transmit-3 levels

orMLT-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 noise

environments Gigabit Ethernet standards are now the dominant

technology for backbone installations, high-speedcross-connects, and general infrastructure needs.


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NRZI Encoding

100BASE-FX uses 4B/5B encoding, which is

then scrambled and converted to non-return-zero-inverse or NRZI.

Class of Repeater

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. Because of the

reduced latency it is possible to have two Class

II repeaters in series, but only if the cable

between them is very short.


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Gigabit and 10-Gigabit Ethernet

1000 Mbps Ethernet

The 1000 Mbps Ethernet or Gigabit Ethernetstandards represent transmission using both

fiber and copper media.

The 1000BASE-X standard (IEEE 802.3z)specifies a 1-Gbps full duplex over optical

fiber.

The 1000BASE-T standard (IEEE 802.3ab)uses a media ofCategory 5e or higher UTP.

1000BASE-TX, 1000BASE-SX, and

1000BASE-LX use the same timingparameters.


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Gigabit Ethernet Encoding

The shorter duration bit times require GigabitEthernet to use two separate encoding steps.

At the physical layer, the bit patterns from the

MAC layer are converted into symbols.

Fiber-based Gigabit Ethernet (1000BASE-X)uses 8B/10B, followed by the simple Non-Return

to Zero (NRZ) line encoding of light on optical

fiber.

Actual 1000BaseT Signal Transmission

Cat 5e cable can reliably carryup to 125 Mbps of traffic.

1000BASE-T uses all four pairs

of wires.

The circuitry has to divideframes at the transmitter and

reassemble them at the receiver.

For1000BASE-T 4D-PAM5 lineencoding is used on Cat 5e or

better UTP. The actual

transmitted signal in each

direction on each wire pair is a 5-level {+2, +1, 0, -1, -2} pulse


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1000BASE-SX and LX

1000BASE-X uses 8B/10B encoding converted to non-return to zero (NRZ) line encoding

Media Access Control

The Media Access Control method treats the link aspoint-to-point. Since separate fibers are used for

transmitting (Tx) and receiving (Rx) the connection is

inherently full duplex.

Gigabit Ethernet permits only a single repeater betweentwo stations.


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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 opticalfiber

Gigabit 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 technology


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10 Gigabit Ethernet

IEEE 802.3ae was adapted to include 10-Gbps full-duplex transmission over fiber-optic cable.

With single-mode fiber, the maximum transmissiondistance is 40 kilometers makes 10GbE a viable MAN

technology .

Compatibility with SONET/SDH networks operatingup to OC-192 speeds (9.584640 Gbps) make 10GbE a

viable WAN technology.

Some discussions between IEEE members havebegun that suggest the possibility of standards for

40-, 80-, and even 100-Gbps Ethernet.

Parameters for 10GbE Operation


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802.3ae 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 fiber

and 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)


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Summary

10Base2, 10Base5, 10BaseT

Line encoding: Manchester, MTL3, NRZI

Characteristics and varieties of 100-Mbps

Ethernet

Characteristics and varieties of 1000-MbpsEthernet

Basic architectural considerations of Gigabitand 10-Gigabit Ethernet

Documents

CCNA1 M7 Ethernet Technologies