Ccna1 M7 Ethernet Technologies

CCNA – Semester1

Module 7 Ethernet Technologies

Objectives

• Ethernet relevant issues • 10 Mbps and 100 Mbps • 1000 Mbps and Gigabit Ethernet

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 layer and medium have changed.

Parameters for 10Mbps Ethernet

Line Encoding • All 10 Mbps forms of Ethernet take octets received from the MAC sublayer and perform a process called line encoding. • Line encoding describes how the bits are actually signaled on the wire. • The form of encoding used in 10 Mbps systems is called “Manchester”.

Manchester Encoding

10BASE-T Wiring and Architecture • 10BASE-T links generally consist of a connection between the station and a hub or switch. • The most important aspect to consider for 10BASET architecture is minimizing the delay between distant stations

100-Mbps Ethernet • •

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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 100BASEFX are: – timing parameters – the frame format – parts of the transmission process.

100Mbps Ethernet Encoding • The higher frequency signals are more susceptible to noise. • Two encoding steps for 100-Mbps Ethernet. – 4B/5B – actual line encoding specific to copper or fiber.

100BASE-TX • 100BASE-TX can be either full-duplex or half-duplex • Ethernet network use separate transmit and receive wire pairs (full-duplex) and a switched topology prevents collisions on the physical bus. • 100BASE-TX uses 4B/5B encoding, which is then scrambled and converted to multilevel transmit-3 levels or MLT-3.

100BASE-FX • A fiber version desired for backbone connections as well as those between floors and buildings where copper is less desirable, and also in high noise environments • Gigabit Ethernet standards are now the dominant technology for backbone installations, high-speed cross-connects, and general infrastructure needs.

NRZI Encoding

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

Gigabit and 10-Gigabit Ethernet

1000 Mbps Ethernet • The 1000 Mbps Ethernet or Gigabit Ethernet standards 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 of Category 5e or higher UTP. • 1000BASE-TX, 1000BASE-SX, and 1000BASE-LX use the same timing parameters.

Gigabit Ethernet Encoding • The shorter duration bit times require Gigabit Ethernet 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 carry up to 125 Mbps of traffic. 1000BASE-T uses all four pairs of wires. • The circuitry has to divide frames at the transmitter and reassemble them at the receiver. • For 1000BASE-T 4D-PAM5 line encoding is used on Cat 5e or better UTP. The actual transmitted signal in each direction on each wire pair is a 5level {+2, +1, 0, -1, -2} pulse

1000BASE-SX and LX • 1000BASE-X uses 8B/10B encoding converted to nonreturn to zero (NRZ) line encoding

Media Access Control • The Media Access Control method treats the link as point-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 between two stations.

1000Mbps Ethernet

• 1000BASE-SX use short-wavelength by 850 nm laser or LED source in multimode optical fiber. • 1000BASE-LX use long-wavelength by 1310 nm laser source uses either single-mode or multimode optical fiber

Gigabit Ethernet Architecture • Daisy-chaining, star, and extended star topologies are all allowed. • The bandwidth of fiber is inherently very large. It has been limited by: – emitter technology – fiber manufacturing processes – detector technology

10 Gigabit Ethernet • IEEE 802.3ae was adapted to include 10-Gbps fullduplex transmission over fiber-optic cable. • With single-mode fiber, the maximum transmission distance is 40 kilometers makes 10GbE a viable MAN technology . • Compatibility with SONET/SDH networks operating up to OC-192 speeds (9.584640 Gbps) make 10GbE a viable WAN technology. • Some discussions between IEEE members have begun that suggest the possibility of standards for 40-, 80-, and even 100-Gbps Ethernet.

Parameters for 10GbE Operation

802.3ae June 2002 10GbE family. • 10GBASE-SR –short distances, multimode fiber, range between 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 40 km over single-mode fiber • 10GBASE-SW, 10GBASE-LW, and 10GBASE-EW –work with 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-Mbps Ethernet • Characteristics and varieties of 1000-Mbps Ethernet • Basic architectural considerations of Gigabit and 10-Gigabit Ethernet