01 Ethernet Principle 20090724 A

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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

thernet !rinciple


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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. !age2

"#$ectives

%pon completion o& this course, you will #e a#le to'

(now the technical #ac)ground o& the thernet and its

#asic concepts

*escri#e the common thernet e+uipment and theirwor)ing principle

%nderstand the &unction o& LA-


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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. !age

Contents

1. Ethernet Concept

2. thernet !ort Technology

. LA- /asis


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0000000

1

1011101

1

0011101

0

1011101

0

1011111

0

1010100

0

t means this is a multicast

address.

thernet 3AC Address

00.e0.&c.4.50. 3AC address includes 5 #its and it is shown as 12 dotted

headecimal notations

3AC address is eclusive glo#ally which is allotted and

managed #y . very 3AC address is composed o& twoparts. The 7rst 2 #its part is the vendor code and the other

2 #its part is serial num#er

& 5 #its are all 819, it means the address is used &or

#roadcast

& the 5th #it is 819, it means the address is used &or multicast


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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. !age:

Ethernet_II

DMAC SMAC Length/T

DATA/PAD FCS

Length/Type Mean

Length;T 1:00

Type o& the &rame

Length o& the &rame802.3

6???1:00 #ytes

6???1:15 #ytes

thernet @rame tructure


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thernet !rinciple???C3A;C*

C' carrier sense ense #e&ore sending data to ensure the ca#le is idle and reduce

collision.

3A' multiple access

The data &rom every station can #e received #y other multiple

stations.

C*' collision detection

*etect collision while sending data and stop it when the station

7nd collision then continue to send a&ter waiting &or a random

time.


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1 2 :

-

"%T "%T"%T"%T

H%/ only changes the physical topology o& thernet,

t is hal& duple.

or)ing !rinciple o& H%/


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!"

LA#

LA#

LA#

LA#

LA#

H%/ only repeats all the signals coming &rom connected LA- and

all the physical e+uipment construct a collision domain.

Collision *omain


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*e&ects o& Traditional thernet

The transmission eDciency is low in case o& manyhosts connected

A lot o& collisions

/roadcast storm

-o security

%se H%/s to construct the LA- as a sharing thernet


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!hysical

layer

*ata lin)

layer

E/F*G;thernet switch;L2 e+uipmentE/F*G;thernet switch;L2 e+uipment

wor) modewor) mode

L2 or) 3ode

Application layer

!resentation layer

Conversation layer

Transport layer

-etwor) layer

*ata lin) layer

!hysical layer!hysical

layer

L2 $%&tch

*ata lin)

layer

Application layer

!resentation layer

Conversation layer

Transport layer

-etwor) layer

*ata lin) layer

!hysical layer


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L2 or) !rinciple ECont.

@orwarding #ased on destination address

!ort 1

!ort 2

L2 S%&tch

MACD MACA '''

MACA MACD '''

MAC ADD. port

3AC A 1

3AC / 1

3AC C 2

3AC * 2


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L2 witch !rinciple

Feceive all the data &rames &rom the networ) segment ave the source 3AC addresses o& the received &rames to

esta#lish 3AC address ta#leE sel&?learning #ased on source

address and maintain the address ta#le #y aging mechanism

Chec) the 3AC address ta#le to 7nd out the port corresponding

to the destination address. & it is the receiving port, it will ta)e

the &rameI i& it is not the receiving port, the data will #e

#roadcasted to all the other ports Eecept the source port

@orward #roadcast and multicast &rames to all other ports

Eecept the source port


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Three witch3odes

Cut?Through witch &orward the &rame immediately a&ter it receive destination address

hort time delay

witch donJt chec) the error

tore?and?@orward

witch &orward the &rame a&ter it receive the whole &rame

Long time delay

witch chec) the error so no error &rame will #e &orwarded

@ragment?&ree

witch &orward the &rame a&ter it receive 6 #ytesE the shortest &ramelength

ntegrate the advantage o& the cut?through and store?and?&orward mode


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L2 will &orward the received &rames according to the 3ACaddress so collision domain is limited to one port. /ut it

can not limit the #roadcast domain.

/roadcast *omain

S(ITC

LAN

LAN

LAN

LAN

LAN

/roadcastdomain

collision domain

collision domaincollision domain

collision domain collision domain


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Contents

1. thernet Concept

2. Ethernet Port Techno)ogy

. LA- /asis


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Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. !age1B

thernet ConnectionFe+uirements

thernet connection must ensure the per&ormance o&the networ)

/andwidth

*elay

Two methods to increase #andwidth &or users'

ncrease the overall networ) #andwidth

/uild switching thernet, and use #andwidth eclusively.

ncrease lin) rate' 103??1003??10003

*ecrease the num#er o& e+uipment attached to the same

shared medium


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Techn&ca)

Stan*ar*Type$ o+ Ca,)e

Tran$-&$$&o

n D&$tance

100/aseTK 2 pairs A;TA Type : E%T! %nshielded Twisted !air 100m

100/aseT

pairs A;TA Type , and : E%T! %nshielded Twisted

!air 100m

100/ase@K 3ulti?3ode @i#er E33@ ca#le ::0m?2)m

1000/aseCK Copper shielded twisted?pair 2:m

1000/aseT

Copper A;TA Category : E%T! %nshielded twisted?pair,

pair 100m

1000/aseK 3ulti?mode 7#er, :0;62.:um 7#er, use 5:0nm laser ::0m;2B:m

A' lectronics ndustries Association

TA' Telecommunications ndustries Association

Transmission *istance o& @astthernet


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& there is no auto?negotiation mechanism, the&ollowing pro#lems will arise'

Cannot realie the auto dual?rate con7guration &unction

o& the port Esuch as 103#it;s and 1003#it;s

Cannot con7rm the operation mode o& duple

Cannot con7rm whether itMs in need o& the Now?control

&unction or not

& #oth o& the e+uipment provide auto?negotiationthen, it is the #est choice.

thernet Technology???Auto?-egotiation


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@ast lin) pulse includes a series o&cloc);digital se+uence comprised o& lin)

integration test pulse.

The #asic mechanism o& the auto?negotiation&unction is to encapsulate the negotiation message

into the lin) integration test pulse.

1-$

very pulse includes 16 digital se+uence

OO

@ast lin) pulse

thernet Technology???Auto?-egotiation ECont.


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Auto?-egotiation

& one device can not support auto?negotiation, the otherdevice that can support auto?negotiation will wor) at the

de&ault wor) method.

a)+Dp)e F))Dp)e

10M upport upport

100M upport upport

1000M upport

10 upport


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Auto?-egotiation on "ptical@i#er

@or the optical 7#er thernet, the conclusion is' The operation modes at two ends o& the lin) must #e

manually con7gured Espeed, duple modes, Now?

control and etc.

The auto?negotiation o& Giga#it thernet has #een

realied


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@low Control

The &unction o& Now control is to prevent &rames &rom#eing lost in case o& congestion

%nder hal& duple mode, the Now control is achieved

#y #ac)pressure technology %nder &ull duple mode, the Now control generally

a#ides #y standard 502.


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Hal& *uple @low Control

,acpre$$re

!retend that there iscollision, then you willnot constantly

trans&erP


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!A% @rame

*ATA @rame

@ull *uple @low Control

502. standard de7nes a new method named!A% &rame, to realie the Now control in the &ull

duple environment.

!A% &rame uses a reserved multicast addresswhich wouldnMt #e repeated #y #ridge or switch

top Congestion


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Contents

1. thernet Concept

2. thernet !ort Technology

3. 4LA# "a$&$


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"roa*ca$t 5oo*&ng &$ the -a&n *&$a*6antage o+L2 $%&tch

*isadvantage o& @ull *uple andL2 witch

@ull duple and L2 ma)e thernet progress, resolvethe conNict pro#lem and improve the thernet

per&ormance. @urthermore the security is enhanced

to some etent. /ut the &ollowing disadvantages are

still in the thernet'

/roadcast Nooding

ecurity canJt #e guaranteed completely


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Cause o& LA- Generation???/roadcast torm

,roa*ca$t


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/roadcast domain1LA- 10

/roadcast domain2LA- 20

/roadcast domainLA- 0

ngineering *epartment

@inancial *epartment3ar)eting *epartment

Pre6ent "roa*ca$t Stor-6&a 4LA#

!revent /roadcast torm


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MAC 4LA#

3AC A :3AC / 10

3AC C :

3AC * 10

MAC A MAC " MAC C MAC D

S%&tch

Port 4LA#

!ort 1 :!ort 10

!ort B :

!ort 10 10

PC A PC " PC C PC D

S%&tch

Port 1

Port 3Port 7

Port 10

LA- /ased on 3AC or !ort


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Protoco) 4LA#

!K :%*! 10

! 2

OOO. 11

IP IP !DP IP

S%&tch

IP 4LA#

1.1.1.1;2 :1.1.2.1;2 10

1.1..1;2 2

OOO. 11

1.1.1.1/29 1.1.2.1/291.1.3.1/292.1.1.1/29

S%&tch

LA- /ased on !rotocol oru#net


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@rame @ormat o& LA-

*A A Type *ata CFC

tandard thernet @rame

*A A Type *ata CFCtag

T!* !riority C@ LA- *

TC

Ethernet Fra-e %&th IEEE802.I: F)ag


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LA- 2 LA- 1

LA- 1 LA- 2

thernet &ramewith LA- tag 1

thernet &ramewith LA- tag 2

thernet &ramewithout LA-

Nag

@rame Changes in -etwor)Communication


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thernet Card !ort Tag 3ode

Pacet$

Port

Tag 5ag !ntag 5ag

Tag aware En Transmit transparently *rop

Tag aware

E"utTransmit transparently

Access En *ropAttach a Tag Nag Ede&ault

LA- *

Access E"utFemove the Tag Nag Ede&ault

LA- *

Hy#rid En Transmit transparentlyAttach a Tag Nag Ede&ault

LA- *

Hy#rid E"ut

& LA- * is the same,

remove the Tag Nag,

otherwise transmit

transparently


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Advantage and *isadvantage o&LA-

LA- technology resolves the #roadcast pro#lemand enhances the communication security.

*isadvantage o& LA-'

mprove the #andwidth utiliation rate #y dividing aphysically interconnected networ) into several small

logic networ)s. /ut what should we do i& diQerent

LA-s need to communicate with each otherR


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Suestions

!lease descri#e the wor)ing mechanism o& L2witchR

hat is the advantage o& LA-R


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01 Ethernet Principle 20090724 A

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