802.3 Ethernet

802.3 802.3z 802.3u比较

IEEE 802.3 Ethernet IEEE 802.3u Fast Ethernet IEEE 802.3z Gigabit Ethernet ANSI X3T9 Fibre Channel

802.3 802.3z 802.3u比较

Ethernet– Table of Contents

Part 1: IEEE 802.3 Ethernet

Part 2: IEEE 802.3u Fast Ethernet

Floor 4

Ethernet/ Fast Ethernet Switch

Part 3: IEEE 802.3z Gigabit EthernetFloor 3 Hub Stack

Fast Ethernet Switch

Bridge/ Router Floor 1

WAN

Broadband Network Technologies

IEEE 802.3 Ethernet2

802.3 802.3z 802.3u比较

Ethernet– History

Developed by Xerox Palo Alto Research Centre First published by Digital Equipment, Intel, and Xerox as DIX (DEC, Intel, Xerox) standard Strongly changed and standardised by IEEE in the IEEE 802.3 Therefore, two different versions are existing:– Ethernet version 2 (DIX)– IEEE 802.3– differences are mainly in the Media Access frame Topology of an Ethernet is logically (mostly physically, too) a bus

Broadband Network Technologies

IEEE 802.3 Ethernet3

802.3 802.3z 802.3u比较

Ethernet– Technological Overview A lot of standards exist for different Ethernet versions:– 1Base5 (Starlan), 10Base5 (Ethernet), 10Base2 (Cheapernet)– 10BaseT, 10BaseF, 10Broad36– 100BaseTX, 100BaseFX, 100BaseT2, 100BaseT4– 1000Base-LX, 1000Base-SX, 1000Base-CX, 1000Base-T– 100BaseVG, 100VG-AnyLAN First number identifies transfer rate (1=1MBit/s, 10=10MBit/s, ...) Base= baseband transmission, Broad= broadband transmission Last digit, number, or character identifies characteristics of the transmission medium:– T= twisted pair, FX/LX/SX= fibre optics, CX= shielded balanced copper, T4= 4 pair twisted pair, T2= 2 pair twisted pair– length of a segment - 2=185m, 5=500mIEEE 802.3 Ethernet4

Broadband Network Technologies

802.3 802.3z 802.3u比较

Part 1: Survey

Part 1: IEEE 802.3 Ethernet– Physical Layer– Medium Access– Configuration Rules

Part 2: IEEE 802.3u Fast Ethernet

Part 3: IEEE 802.3z Gigabit Ethernet

thick coax segment (500m max)

MAU15-pin AUI connector

coax tap (MDI)

transceiver AUI cable (50m max)

Ethernet interface with external MAU

male"N" connector 50 Ohm terminator

Broadband Network Technologies

IEEE 802.3 Ethernet5

802.3 802.3z 802.3u比较

IEEE 802.3 Ethernet– IntroductionApplications

Management

CSMA/CD MAC

AUI Interface

10Base5 (Thick Coax)

10Base2 (Thin Coax)

10Base-T (UTP cat 3,4,5)

10Base-F (Fibre)

Ethernet Physical Layer (PHY) OptionsBroadband Network Technologies IEEE 802.3 Ethernet6

802.3 802.3z 802.3u比较

Physical Layer Tasks of the physical layer defined as:– send and receive bit streams– collision detection– encoding and decoding of signals– generation of the preamble– generation of clocks for synchronisation– testing of the transmission of data from the station up to the Medium Access Unit (MAU)

Broadband Network Technologies

IEEE 802.3 Ethernet7

802.3 802.3z 802.3u比较

Physical Layer (cont.)– Architectural ModelHigher Protocol Layer Logical Link Control (LLC) Medium Access Control (MAC) PLS Physical Layer

MDI

transmission mediumPLS AUI PMA Physical Signalling Sub-layer Attachment Unit Interface Physi

cal Medium Attachment MDI MAU Medium Dependent Interface Medium Attachment Interface

Broadband Network Technologies

MAU

PMA

AUI

standardised in IEEE 802.3

IEEE 802.3 Ethernet8

802.3 802.3z 802.3u比较

Medium Access– CSMA/CD

Shared medium access is realised with Carrier Sense Multiple Access with Collision Detection (CSMA/CD)– each station is listening to the carrier (carrier sense)– if no transmission takes place, stations can send data to any other station (multiple access)– if two or more stations send data at the same time, each station has to stop further transmission (collision detection)– after a certain time (random for each station), stations can try to send data again CSMA/CD needs– multiple stations connected to a segment (multiple access)– sense of the carrier before data is sent (carrier sense)– sense of the carrier during data transmission (collision detection)

Broadband Network Technologies

IEEE 802.3 Ethernet9

802.3 802.3z 802.3u比较

Medium Access (cont.)– Domains

Router Ethernet

Bridge/ Switch Ethernet

Repeater/ Hub Ethernet

Ethernet

Collision Domain

Broadcast Domain

Broadband Network Technologies

IEEE 802.3 Ethernet1

802.3 802.3z 802.3u比较

Medium Access (cont.)– IEEE 802.3 FramesIEEE 802.3 Ethernet MAC frames

PA 7

SFD 1

DA 6

SA 6

LEN 2

LLC 3/4

Data

PAD variable

FCS 4

PA DA SA SFD

preamble destination address source address start frame delimiter

LLC PAD FCS LEN

logical link control padding frame check sequence (CRC-32) lengthIEEE 802.3 Ethernet1

Broadband Network Technologies

802.3 802.3z 802.3u比较

Configuration Rules

Basically two models exist for the configuration of multi-segment Ethernet networks: 1. A model employing conservative calculations 2. A model employing IEEE standardised configuration aids with two phase calculation (first the correct round trip signal propagation, than the amount of Interframe Gap shrinkage)

System not built with these guidelines can work, but usually not for a long time Especially a growing network (by size or traffic load) should not violate this recommendations (IEEE 802.3)

Broadband Network Technologies

IEEE 802.3 Ethernet1

802.3 802.3z 802.3u比较

Configuration Rules (cont.)– Model 1

R500m

10Base-FL link 500m

R

500m 10Base-5 mixing

10Base-FL link 500m 10Base-5 mixing

DTE 210Base-T link 100m

R

DTE 1185m 10Base-2 mixing

R

DTE 3

RBroadband Network Technologies

Repeater

IEEE 802.3 Ethernet1

802.3 802.3z 802.3u比较

Configuration Rules (cont.)– Model 2

Defines two sets of methods, which have to be performed both First set ensures that the round trip signal propagation is within the limits Second set verifies the amount of Interframe Gap shrinkage A simplified network topology (Generalised Transmission Path Model) is used to for the path delay calculation

DTE 1

MAU

MAU

Repeater

MAU

MAU

Repeater

MAU

MAU

DTE 2

left segment

middle segment

right segment

Broadband Network Technologies

IEEE 802.3 Ethernet1

802.3 802.3z 802.3u比较

Part 2: IEEE 802.3u Fast Ethernet

Part 1: IEEE 802.3 Ethernet

Part 2: IE

EE 802.3u Fast Ethernet– Introduction– 100Base-T Overview– 100Base-TX– 100Base-FX– 100Base-T4

Ethernet/ Fast Ethernet Switch

Ethernet/ Fast Ethernet Switch

Part 3: IEEE 802.3z Gigabit Ethernet

Fast Ethernet Hub

Broadband Network Technologies

IEEE 802.3 Ethernet1

802.3 802.3z 802.3u比较

Fast Ethernet– Technological Overview I

Two different technologies exist for 100MBit/s Ethernet– IEEE 802.3u 100Base-T (100Base-TX, 100Base-FX, 100Base-T4, 100Base-T2)– IEEE 802.12 100VG-AnyLAN 100Base-T– supports the common Ethernet mechanisms (CSMA/CD) 100VG-AnyLAN– creates an entirely new medium access control mechanism– is based on hubs that control access to the medium using a demand priority– further extended to allow to transport token ring frames

Broadband Network Technologies

IEEE 802.3 Ethernet1

802.3 802.3z 802.3u比较

Fast Ethernet– Technological Overview II100 MBit/s Ethernet

100VG-AnyLAN

100Base-T

100Base-T2

100Base-X

100Base-4

100Base-TXBroadband Network Technologies

100Base-FXIEEE 802.3 Ethernet1

802.3 802.3z 802.3u比较

IEEE 802.u Fast Ethernet

Aims of the IEEE 802.3u Fast Ethernet working group– support of CSMA/CD with bit rate of 100 MBit/s– identical MAC frame format– support of twisted pair and fibre optics as physical medium– interoperability between 10Base-T and 100Base-TX components Fast Ethernet Consortium develops technology and is accepted by the IEEE 802.3u working group The Fast Ethernet Consortium was formed in December of 1993 and is one of the consortiums at the University of New Hampshire Inter Operability Lab (IOL). The Consortium was formed through the cooperative agreement of vendors interested in testing Fast Ethernet products.

Broadband Network Technologies

IEEE 802.3 Ethernet1

802.3 802.3z 802.3u比较

IEEE 802.u Fast Ethernet (cont.)– OverviewApplications

Management

CSMA/CD MAC

MII Interface

100Base-FX (Fibre)

100Base-TX (UTP cat 5)

100Base-T4 (UTP cat 3,4,5)

Fast Ethernet Physical Layer (PHY) OptionsBroadband Network Technologies IEEE 802.3 Ethernet1

802.3 802.3z 802.3u比较

Physical Layer– 100Base-XScheme of the 100Base-X standardLLC MACReconciliation

MII PCS Physical Layer PMA PMD MDI PCS PMA PMD

100Base-X repeater PCS PMA PMD MDI MDI

MediumBroadband Network Technologies

MediumIEEE 802.3 Ethernet2

802.3 802.3z 802.3u比较

Physical Layer (cont.)– 100Base-T4Scheme of the 100Base-T4 standard

LLC MACReconciliation

MII PCS PMD MDI

MediumBroadband Network Technologies IEEE 802.3 Ethernet2

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