Computer networks ethernet technologies

Computer networks, ethernet technologies, mạng máy tính, công nghệ ethernet

Ethernet Technologies

Outline

10-Mbps and 100-Mbps Ethernet

10-Mbps Ethernet 10BASE5

10BASE2 10BASE-T

10BASE-T wiring and architecture

100-Mbps Ethernet 100BASE-TX

100BASE-FX Fast Ethernet architecture

Gigabit and 10-Gigabit Ethernet

2008/7/19

1000-Mbps Ethernet 1000BASE-T

7.1 10-Mbps and 100-Mbps Ethernet

2008/7/19

Slot Time 512 bit times Interframe Spacing 96 bits * Collision Attempt Limit 16 Collision Backoff Limit 10 Collision Jam Size 32 bits Maximum Untagged Frame Size 1518 octets Minimum Frame Size 512 bits (64 octets)

10-Mbps Ethernet (cont )

The four common features of Legacy Ethernet (cont.) :

The same transmission process

SQE (signal quality error), it is always used in half-duplex SQE can be used in full-duplex operation but is not required

Manchester line encoding

Falling edge > bit 0 Raising edge > bit 1

The same basic design rule

The timing limits

Cable length and its propagation delay Delay of repeaters

Delay of transceivers

Interframe gap shrinkage (1§)

Delays within the station

5-4-3 rule

No more than 5 segments

No more than 4 repeators

No more than 3 populated segments between any two

distant stations.( 8 = segments n[‡š4ïglj )

10BASES5

A single thick coaxial cable bus

10BASE5 is the first medium used for Ethernet

Manchester encoding The primary benefit of 1OBASE5 was length Each of the maximum five segments of thick

coax may be up to 500 m (1640.4 ft) in length The cable is large, heavy, and difficult to

install

2008/7/19

10BASE2

Manchester encoding The cable is smaller, lighter, and easier to install than 10BASE5

BNC connectors / T-shaped connector

Termination of each end of the coax should be 50 Ohms

Minimum distance between taps is 0.5 meters

Each station must connect within four centimeters of the thin coax

Maxiumum segment lenth is 185 meters

Link segments between repeaters should have a total of only two attachments, the

1OBASE-T

Manchester encoding Category 3 / Category 5e HJ-45

Pin Number Signal

TD+ (Transmit Data, positive-going differential signal) TD- (Transmit Data, negative-going differential signal) RD+ (Receive Data, positive-going differential signal) Unused

Unused RD- (Receive Data, negative-going differential signal) Unused

Unused

1OBASE-T wiring and architecture

1 UTP Link Segment cable length is 1 to 100 meters normal between the section

and the hub, and between the hubs

2 Each hub is a multi-port repeater, so links between hubs count toward the

Bit Time 10 nsec Slot Time 512 bit times Interframe Spacing 96 bits

Collision Attempt Limit 16

Collision Backoff Limit 10

Maximum Untagged Frame Size 1518 octets Minimum Frame Size 512 bits (64 octets)

100BASE-IX

100BASE-TX uses 4B/5B encoding, which is then scrambled and converted to multi-level transmit-3 levels or MLT-3

Rising or falling edges indicate 1s

Any noticeable horizontal line in the signal indicates a 0

100BASE-FX

100BASE-FX uses 4B/5B encoding

| 1 _Tx (LED and laser transmitters)

E Rx (high-speed photodiode detectors) One Bit Period

Fast Ethernet Architecture

(half or full duplex) One Class |

Fast Ethernet Architecture (Cont )

m@ Class | repeater may introduce up to 140 bit-times

latency

Class | repeater changes between one Ethernet

implementation and another

m@ Class II repeater is restricted to smaller timing

delays, 92 bit times

m@ Class Il repeater immediately repeats the incoming

signal to all other ports without a translation process

Class II repeaters can only connect to segment types that use the same signaling technique

7.2 Gigabit and 10-Gigabit Ethernet

1000-Mbps Ethernet

—— This high-speed

transmission requires SE ————

medium bandwidth Collision Backoff Limit 10

limitations Collision Jam Size 32 bits

(1000BASE-X) uses 8B/10B #S'“” —

the 4B/5B concept HHA HLH

1000BASE-T

Cat 5e cable can reliably carry up to 125 Mbps of traffic

250 Mbps per pair 4D-PAM5 line encoding The information travels simultaneously across the four paths, the circuitry has to divide frames at the transmitter and reassemble them at the receiver

There are 17 voltage levels found on the cable

¢ encoded, transmitted and

detected in parallel,

and then reassembled into one received bit

stream

«Figure represents the simultaneous full duplex on four-wire

* No grounding potential problems

* Excellent distance characteristics

* Many 1000BASE-X device options

* Can be used to connect widely dispersed Fast Ethernet segments

Full Duplex and/or Half Duplex

1000BASE-LX Gigabit Media Independent

1000BASE-LX} |1000BASE-SX} '1000BASE-CX 1000BASE-T

25m 50m 250m 500m 2500m 5000m

10-Gigabit Ethernet

Collision Attempt Limit not applicable * Collision Backoff Limit not applicable * Collision Jam Size not applicable * Maximum Untagged Frame Size 1518 octets Minimum Frame Size 512 bits (64 octets) Burst Limit not applicable * Interframe Spacing Stretch Ratio 104 bits ***

* 10-Gbps Ethernet does not permit half duplex operation, so parameters related to slot timing and collision handling do not apply

** The value listed is the official interframe spacing

*** The Interframe Spacing Stretch Ratio applies exclusively to 1OGBASE-W definitions

10-Gigabit Ethernet (cont.)

To summarize, how does 10GbE compare to other varieties of Ethernet?

2008/7/19

Frame format is the same, allowing interoperability between all

varieties of legacy, fast, gigabit, and 10 Gigabit, with no reframing or protocol conversions

Bit time is now 0.1 nanoseconds All other time variables scale accordingly

Since only full-duplex fiber connections are used, CSMA/CD Is not

necessary The IEEE 802.3 sublayers within OSI Layers 1 and 2 are mostly

preserved, with a few additions to accommodate 40 km fiber links and

Interoperability with SONET/SDH technologies

Flexible, efficient, reliable, relatively low cost end-to-end Ethernet networks become possible

TCP/IP can run over LANs, MANs, and WANs with one Layer 2 Transport method

22

10-Gigabit Ethernet (cont.)

As is typical for new technologies, a variety of implementations are

being considered, including:

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 1OGBASE-W are intended to work with OC-192 synchronous transport module (STM) SONET/SDH WAN equipment

some discussions between IEEE members have begun that suggest the possibility of standards for 40, 80, and even 100-Gbps Ethernet

The ratio of their hierarchies reflects exactly the ratio of

their capacity (e.g 4 * STM-1 lines = 1 STM-4 line)

Currently, higher capacity over OC-192 is achieved by wavelength

division multiplexing (WDM) technologies

2008/7/19

10-Gigabit Ethernet architectures

Because of the short

duration of the 10 GbE data bit, it is often difficult to

separate a data bit from

noise

Complex serial bit streams

are used for all versions of

10GbE except for

10GBASE-LX4, which 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

Optical Optical Optical Optical

Transmitter Transmitter Transmitter Transmitter

> WDMultiplexer y

Fiber Optic

Medium

25

Future of Ethernet

Ethernet has gone through

an evolution from Legacy — Fast — Gigabit —

MultiGigabit technologies

The future of networking media is three-fold:

100 Mbps, perhaps more) Optical fiber (currently at 10,000 Mbps and soon to

Significant MAN Implementations

perh aps more) Special WAN Applications;

LAN "Dial Tone" End-to-End Ethernet, TCP/IP

Wireless (approaching

26

» END