Ori000008 Atm Principle (Bss)Issue4.2

8/8/2019 Ori000008 Atm Principle (Bss)Issue4.2

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Wireless Curriculum Development SectionWireless Curriculum Development SectionWireless Curriculum Development SectionWireless Curriculum Development Section

ISSUEISSUE

ORI000008 ATM PrincipleORI000008 ATM PrincipleORI000008 ATM PrincipleORI000008 ATM Principle

4.24.2


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Confidential Information of Huawei.

No Spreading without Permission.Security Level: Internal

Course OutlineCourse Outline

Overview

Basic Concepts of ATM

ATM Protocol & Service Type

Basic Concepts of IPOA

ATM in CDMA2000 BSS


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To provide a high-speed, low delay

multiplexing and switching network to any type of

user traffic, such as voice support, data,or video

applications.

Why do we need a new technology?


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What is ATM?What is ATM?

ATM for Telecommunications is Asynchronous Transfer Mode, (not

Automatic Teller Machine!).

ATM is a technology that has transport, switching, network

management, and customer services built into it right from the start.

In general, ATM means that traffic is carried in small, fixed-length

packets called cells.

A technology that integrates advantages ofcircuit switch and packet

switch.

ATM can support any type of user services, such as voice, data, or

video service.


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ATM OverviewATM Overview

53byte fixed length cell= 5Bytes cell

header+48Bytes payload.

ATM must set up virtual connection beforecommunication.

ATM network will confer with terminal onparameter of QoS before the connection is

set up.

Contract

5-Bytes

Header

48-Bytes

Payload


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Connectionless & Connection-orientedConnectionless & Connection-oriented

Connectionless: Every packet is

transferred from different routes, so

the receiving order of packets

doesnt possibly depend on the

sending order.

Connection-oriented : All packetsare transferred from the same

route , so the receiving order of

packets depends on the sending

order. Time delay is fixed.


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Traditional Switch Models CharacteristicTraditional Switch Models Characteristic

Circuit Switching Data is sent from the same route, so time delay is fixed

High-speed switching Fixed rate

Packet Switching

Support multi-rate switching

Take full advantage of bandwidth/waste of bandwidth

Time delay is not fixed


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ATM Switch Models CharacteristicATM Switch Models Characteristic

Bandwidth will be shared and statistically

multiplexed, any users cell will not be send

periodically.

Many types of service can be transferred in the

same time with high QoS.

Fixed length cell, so switch can be controlled by

hardware and high-speed switching is easy to be

realized.


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Overview




ATM in CDMA2000 BSS


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ATM CellATM Cell


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ATM CellATM Cell

GFC ( Generic Flow Control): It is intended for control of a possible bussystem at the user interface and is not used at the moment.

VPI ( Virtual Path Identifier): The VPI contains the second part of the

addressing instructions and is of higher priority than the VCI.

VCI ( Virtual Channel Identifier): VCI in each case indicates a path section

between switching centers or between the switching center and the subscriber.

PTI ( Payload Type Identifier): Indicates the type of data in the information

field.

CLP ( Cell Loss Priority): Determines whether a cell can be preferentially

deleted or not in the case of a transmission bottleneck.

HEC ( Header Error Control): Provided in order to control and, to some

extent, correct errors in the header data that may occur. The HEC is used to

synchronize the receiver to the start of the cell.


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VP and VCVP and VC

Why two fields?

Consider VPI as a bundle of virtualchannels. (256 VPI on one link)

The individual virtual channels have

unique VCIs. The VCI values may

be reused in each virtual path.


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Port 1VPI=2 VCI=37

VPI=3 VCI=39

NNI

UNI

UNI

ATM Cell Switching

ATM Switch

Port VPI VCI

1 2 37

2 1 51Port 2

Port 1 ATM Switch

Port VPI VCI

1 1 51

2 3 39

Port 2

ATM TerminalUser B

User A

ATM Network Node

Cell and users

data change

each other

VPI=1 VCI=51

ATM Network Node

ATM Terminal

Cell and users

data change

each other


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ATM ConnectionsATM Connections


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ATM Virtual ConnectionATM Virtual Connection

UNI cell

VPI =1

VCI =1

UNI cell

VPI =20

VCI =30

NNI cell

VPI =26VCI =44

NNI cell

VPI =6

VCI =44NNI cell

VPI =2

VCI =44

1

2

3

1

2

3

1

3 2

2

31

ATM Virtual Connection

Port VPI VCI

1 26 442 2 44

Port VPI VCI

1 2 44

2 6 44

Port VPI VCI

2 6 44

3 20 30

Port VPI VCI

1 1 1

2 26 44A B

In order to exchange cells between A and B, several tables must be set up in

network node where the cells passed. After these tables have been set up, all the

cells will be transferred along this route. This route is calledV

irtual Connection.


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Types of ATM Virtual ConnectionTypes of ATM Virtual Connection

According to the switching mode, ATM

Virtual Connection can be classified :

VPC (Virtual Path Connection)

VCC (Virtual Channel Connection)

According to connection establishment,

ATM Virtual Connection can be classified: SVC(Switching Virtual Connection)

PVC(Permanent Virtual Connection)


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UNI cell

VPC and VCCVPC and VCC

ATM terminal AC

ATM network node G UNI cell

NNI cell NNI cell

VC

switching

VCC

VPC

VCC

UNI cell UNI cell

B D

For example: When E receives cells from A or B, which would betransferred to C or D, the VPI of these cells would be set to

uniform value in E. These cells would be received by G and

switched to F by VP switching. Then the cells will be delivered to

C or D at F. It means that VPC has been set up between E and F,

while VCC has been set up among A, B , C and D.

E F

VP

switching

VC

switching


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Overview




ATM in CDMA2000 BSS


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ATM Protocol Structure ModelATM Protocol Structure Model

USER

SAAL

ATM Layer

Physical Layer

AAL

USERService and signaling

of user

Information of user

and cell conversion

Cell exchange andmultiplexing or

demultiplexing

Frame structure

physical medium

Impartiblemanagement

of all layer

Independentmanagement

of every layer

Call connection

and Control

User informationFlow

Control and Error Recovery

Interface Management

Layer Management

Control interface User interface


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Three Communications PlanesThree Communications Planes

The user plane transports the user data for an application. It

uses the physical,ATM andATM adaptation layers to do this.

The control plane takes care of establishing, maintaining and

clearing down user connections in the user plane. The key word

here is signaling.

The management plane includes layer management and plane

management. Layer management monitors and coordinates the

individual layer tasks. Plane management handles monitoring

and coordination tasks in the network.


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ATM Sublayer ModelATM Sublayer Model

ATM Protocol Stack Model OSI Reference Model

User

PMD

TC

PHY

ATM

AALCS

SARInterface

manage

ment

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data link

1 Physical


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Two sublayers:

Transmission Convergence Sublayer (TC)

transmission frame generation/recovery Processing HEC

cell delimiting

transmission frame adaptation

Physical Medium Dependent Sublayer(PMD)

Link coding

Network physical medium

Function of ATM Physical Layer

AAL

ATM

PHY


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Cell switch

Quality of Service

Processing the cell header

Types of payload

Multiplexing /Demultiplexing of

different connection cell

Function of ATM Layer

AAL

ATM

PHY


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Support services for user

Segment and reassemble

Complete the change between

User-PDU and ATM payload

Function of AAL layer

AAL

ATM

PHY


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Function of ATM AAL OverviewFunction of ATM AAL Overview

Function of ATM AAL:

Provide a high-speed,

low delay multiplexing

and switching network

to support any type of

user service, such as

voice, data,or video

applications.

ATM Payload

Constant

Bit Rate

Data

Bursts

Variable

Bit Rate

ATM Cell

Multiplexing

AAL SDU


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Types of AALTypes of AAL

In order to support different types of user services, there are

five types of AAL.

In Huaweis BSS, voice is transferred over AAL2 and rest

signals are transferred over AAL5.

Service type A B C D

Bit rate constant variable variable variable

Real time YES YES NO NO

Connection mode Connection oriented connectionless

AAL AAL1 AAL2 AAL3/4 AAL5


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Service Types of ATM layerService Types of ATM layer

CBR (Constant bit rate)

VBR-RT (Variable bit rate-real time)

VBR-NRT (VBR-non real time)

UBR (Unspecified bit rate)

ABR (Available bit rate)


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Service type in CDMA2000 BSS SystemService type in CDMA2000 BSS System

Variable bit rate real time(VBR-RT), such as voice

service in CDMA2000 BSS System. It is realized by

AAL2.

Variable bit rate non real time (VBR-NRT), such as

signaling and other service in CDMA2000 BSS System.

It is realized by AAL5.


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Confidential Information of Huawei.No Spreading without Permission.

Security Level: Internal


Overview




ATM in CDMA2000 BSS


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IPOA Protocal StackIPOA Protocal Stack

ATM network Physical layer

IP address is mapped to PVC

or SVC

User application

ATM

AAL

IP

TCP/UDP

ATM

AAL

IP

TCP/UDP

IP packet is transferred to

ATM Payload

User application


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TCP/IPProcessTCP/IPProcess

App DataTCP Header

TCP header App DataIP Header

IP Header TCP Header App DataLLC

SAR-SDU#1 SAR-SDU#2 SAR-SDU#3 SAR-PDU#4 SAR-PDU#5

TCP

IP

SNAP/LLC

AAL5

CS

SAR

ATM

PHY

Cell header will be added to SAR-PDU, whose VPI and VCI depends onthe map table of IP address to PVC/SVC. Then, the cells will be sent to

Physical Layer.

Perform the transmission of ATM cells via physical media.

LLC IP Header TCP Header App Data PAD CPCS-PDU Tail


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INARP in IPOANetwork ModelSVC

mode

INARP in IPOANetwork ModelSVC

mode

ATM NetworkARP Server

Ethernet

WAN

Router


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INARP in IPOANetwork ModelPVC

mode

INARP in IPOANetwork ModelPVC

mode

ATM Network

Ethernet

WAN

Router


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INARP in IPOAPVC ModeINARP in IPOAPVC Mode

Terminal A IP:192 .168 .1 .1

ATM Network

Terminal B IP:192 .168 .1 .2

PVC

Any IPOA terminal that wants to communicate with other terminal

must know the destination IP address. But how to know the IP address?PVC connecting the source and destination terminals should be set up

first. For example: TerminalA must set up a PVC to B in order to know

the IP address of B.


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ARP in IPOAPVC ModeARP in IPOAPVC Mode

TerminalA will send InvATMARP information to request remote IPOA

client s (such as computer B) IP address. So does computer B.

Computer A IP:192 .168 .1 .1

ATM Network

Computer B IP:192 .168 .1 .2

PVCInvATMARP

InvATMARP

VPI VCI IP Address

1 33 ...

XX YY ...

VPI VCI IP Address

2 33 ...

ZZ YY ...


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Thereby,A and B establish the map table ofIP address to PVC. Similarly, all

the IPs of the computers that answered the InvATMARP will be set to themap table.

Computer A IP:192 .168 .1 .1

ATM Network

Computer B IP:192 .168 .1 .2

PVCACK

ACK

VPI VCI

1 33

XX YY

IP Address

192 .168 .1.2

xxx .xxx .xxx .xxx

VPI VCI

1 33

ZZ YY

IP Address

192 .168 .1.1

xxx .xxx .xxx .xxx


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For example: A will transfer a IP packet to B, and the IP packet

will be changed to AAL-PDUs first. When ATM layer receives AAL-PDU,it can find the PVC by map table and set VPI/VCI of ATM cell.

Thereby, cells could be transferred to B by ATM network.

omputer A IP:192.168.1.1

ATM Network

Computer B IP:192.168.1.2

PVCATM cell stream ATM cell stream

VPI VCI

1 33

XX YY

IP Address

192 .168 .1.2

xxx .xxx .xxx .xxx

VPI VCI

1 33

ZZ YY

IP Address

192 .168 .1.1

xxx .xxx .xxx .xxx


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Overview




ATM in CDMA2000 BSS


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ATM in CDMA WLL SystemATM in CDMA WLL System

several E1

cables

BTS

BTS baseband frame service/ signal-in-bandAAL2

maintenance / signal-out-band

AAL5

Abis interface:

signal-in-band/serviceAAL2signal-out-band /maintenanceAAL5 IPOA

If Abis interface is connected with several E1 cables,

IMA mode will be adopted to transfer ATM cells.

BSC inside

VoiceAAL2signal/data service:AAL5

maintenanceAAL5 IPOA

Connected

to MSC

Resource &Packet

Subrack

IntegratedManagement

Subrack

(BAM)

Connected to

PDSN

RAC

GPS/Glonass

Receiver

several E1

cables or

Optic fiber

Integrated

Processing

Subrack

Ethernet

cable

LAN


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IMA ModeIMA Mode

PHY

IMA Group

PHY

PHY

PHY

IMA Group

PHY

PHY

Physical Link #1

Physical Link #0

Physical Link #2

Virtual ATM Link

If Abis interface is connected with several E1 cables, IMA mode will be

adopted to transfer ATM cells. In this way, cells of high speed ATM linkcould be transferred on several low speed physical links.

ATM Layer ATM Layer


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SummarySummary

ATM Basics ATM switching is cell switching,it has advantage

of circuit switch and packet switch, connection

oriented .

ATM cell:53byte fixed length cell= 5Bytes cellheader+48Bytes payload

ATM switching

ATM switching has two types:VP and VC switch.

As a rule: only VPI has been changed in VPswitch,Both VCI and VPI have been changed in

VC switch. VPI and VCI is only of effect between

the two ATM physical nodes.


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QuestionsQuestions

State ATM application in CDMA2000 BSS

system?

What is the difference between SVC and PVC?What is the difference between VP switch

and VC switch?


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Documents

Ori000008 Atm Principle (Bss)Issue4.2