Ora000008 Atm Principle (Bss) Issue3.0

7/27/2019 Ora000008 Atm Principle (Bss) Issue3.0

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Wireless Curriculum Development Section

ISSUE 3.0

ORA000008 ATM Principle

(BSS)


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Objectives

ATM theory & concepts

ATM cell format

Protocol stack of ATM especially AAL2 and AAL5 processing

Application of ATM in a CDMA2000 System

At the end of this course, you will be familiar with:


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Course Outline

Chapter 1 Overview

Chapter 2 Basic Concepts of ATM

Chapter 3 ATM Protocol & Service Type

Chapter 4 Basic Concepts of IPOA

Chapter 5 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?

ATM for Telecommunications is Async hrono us Transfer Mode, (not

Automatic Teller Machine!).

ATM is a technology that has transport, swi tching, 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 Overview

53byte fixed length cell= 5Bytes cell

header+48Bytes payload.

ATM must set up virtual connection before

communication.

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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ATM can provides both CBR and VBR transport


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Connectionless & 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 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 Characteristic

Any users cell will not be send periodically, and

bandwidth will be shared and statistically

multiplexed.

Many types of service can be transferred in the

same time and Quality of Service is supported in

an ATM network.

Fixed length cell, so switch can be controlled by

hardware and high-speed switching is easy to berealized.


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ATMs Advantage

Integration of various services such as voice, image, video, dataand multimedia.

Standardization of network structures and components. This

results in cost savings for network providers.

Transmission that is independent of the medium used PDH, SDH,

SONET and other media can be used to transport ATM cells.

ATM is scaleable, i.e. the bandwidth can be adapted extremely

flexibly to meet user requirements.

Guaranteed transmission quality to match the service required by

the user (quality of service, QoS).


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ATMs Application

In Switching:

Traditional Exchange is evolving into Broadband

Exchange by ATMs application

In Transmission: ATM virtual path exchange node and ATM

Add/Drop Multiplexer

In Internet: ATM router applied in IP Switching, Multi-Protocol

Label Switching


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Course Outline

Chapter 1 Overview






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ATM Network Model

UNI

UNI

UNI

PNNI

PNNI

NNI

NNI NNI

NNI

NNI

NNI

NNI

ICI Other

Network

NNINetwork Node InterfaceUNIUser Node InterfaceICIInter-carrier InterfacePNNIPrivate Network Node Interface


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ATM Cell


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ATM Cell

GFC ( Generic Flow Control): It is intended for control of a possible bus

system 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 VC

Why two fields?

think VPI as a bundle of virtual

channels. (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 51

Port 2

Port 1ATM 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 Connections


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ATM Virtual Connection

UNI cell

VPI =1

VCI =1

UNI cell

VPI =20

VCI =30

NNI cell

VPI =26

VCI =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 44

2 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 calledVirtual Connection.


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Permanent Virtual Channel (PVC):The connections are analogous to leased lines that are switched between

certain users. A change can only be made by the network provider. This

type of ATM network often forms the initial stage in the introduction of this

technology.

Switch Virtual Channel (SVC):Users connected to this type of network can set up a connection to the

user of their own choice by means of signaling procedures. This can becompared with the process of dialing a telephone number.

Signaling In ATM


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Types of ATM Virtual Connection

According to the switching mode, ATMVirtual 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 VCC

ATM terminal A C

ATM network node G UNI cell

NNI cell NNI cellVC

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,

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

E F

VP

switching

VC

switching


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Course Outline

Chapter 1 Overview






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Cells

Voice

Data

Video

Connection oriented

Fast packet switching

Statistical multiplexer

Supports voice, data and video service

Provides QoS

Features of ATM


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ATM Protocol Structure Model

USER

SAAL

ATM Layer

Physical Layer

AAL

USERService and signaling

of user

Information of user

and cell conversion

Cell exchange and

multiplexing or

demultiplexing

Frame structure

physical medium

Impartiblemanagement

of all layer

Independent

management

of every layer

Call connection

and Control

User informationFlowControl and Error Recovery

Interface Management

Layer Management

Control interface User interface


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Three Communications Planes

The user planetransports the user data for an application. It

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

The con trol planetakes care of establishing, maintaining and

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

here is signaling.

The management planeincludes 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 Model

ATM Protocol Stack ModelOSI Reference Model

User

PMD

TC

PHY

ATM

AALCS

SAR

Interfacemanage

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 Overview

Function of ATM AAL:

Provide a high-speed,

low delay multiplexingand 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 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 DBit 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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Logic Structure of AAL Layer

CS sublayer

Provide service to upper layer

at AAL-SAP.

The concrete function is

depending on the service type.

CS can be further divided into

SSCS and CPCS.

SAR sublayer:Chop CCS-PDU into ATM

payload with size of 48 bytes or

assemble ATM payload into

CPCS-PDU.

SSCS

CPCS

SAR

SSCS-PDU

CPCS-PDU

SAR-PDU

AAL-PDU

CPCS-SDU

SAR-SDU

ATM-SDU

AALlay

er

AAL-SAP

ATM-SAP

ATM layer


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AAL2 Structure

AAL2 contains two sub-layer, CPS

and SSCS.

The function of SAR is performed

by CPS, SAR sub-layer is null

For AAL2CPS is changeless nomatter which type of service is. But

it is different for SSCS. Sometimes

SSCS maybe null.

SSCS

CPCS

SSCS-PDU

CPS-PDU

AAL-PDU

CPS-SDU

ATM-SDU

AALl

ayer

AAL-SAP

ATM-SAP

ATM layer


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AALLayer

AAL2 Process

AAL-SAP

SSCS-PDU

Payload

SSCS-PDU Header SSCS-PDU Tail

AAL-SDU

CPS-SDU

CPS-PPCPS-PH

CPS-Packet CPS-Packet

SSCS-PDU 45Bit Max

STF CPS-Packet CCPS-PacketCPS-PacketSTF STF

1# 3#2#

1# 3#2#

CPS-PDUPayload 47 Bit

CPS-PDU

ATM-SDU

ATM-SAP

ATM Payload

SSCS

CPS

SN

876543218765432187654321

CID LI UUI HEC

CPS-PH

ATM

Layer

8 7 6 5 4 3 2 1

OSF P

STF

CPS-Packet

PS-Packet PAD

ATM-Header


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AAL5 Structure

AAL5 contains two sub-layers,

CS and SAR sublayer.

CS sublayer is further divided

into SSCS and CPCS.

In order to enhance the effect

of AAL3/4, CPCS and SAR are

appropriately simplified. AAL5

doesnt support multi-usermultiplexing mode.

SSCS

CPCS

SAR

SSCS-PDU

CPCS-PDU

SAR-PDU

AAL-PDU

CPCS-SDU

SAR-SDU

ATM-SDU

AALlay

er

AAL-SAP

ATM-SAP

ATM layer


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AAL5 Process

AAL

Layer

AAL-SAP

CPCS

ATM

Layer

AAL-SDU

CPS-PDU Payload PAD CPS-PDU Tail

UU CPI Length CRC

8 1 8 1 16 132 1

CPS-PDU N48Bytes

PAD

047Bits

SAR-SDU

ATM-SAP

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

ATM-SDU #1

ATM-SDU #2

ATM-SDU #3

ATM-SDU #4

Cell #1

Cell #2

Cell #3

Cell #4

ATM Payload

:ATM Header (AUU=0)

:ATM Header (AUU=1)

AUU

PTI

3 2 1

SAR


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Service 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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ATM Service Categories


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QoSTraffic parameter

low high

Tolerance

Cell delay and cell delay variationCell loss

PCR

Voice and video

CBR Service


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WAN


low highNo QoS

Tolerance

Cell lose

Cell relay variation

UBR Service


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LAN

Overhead

No cell

overhead Uses

congestionfeedbackinstead

5 Byte

Header

48 Byte

Payload


low highPCR

MCR

Tolerance

Cell lossCell delay variation

ABR Service

ATM Service Categories and their


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ATM Service Categories and their

Parameters

ATM S i C t i d A li ti


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ATM Service Categories and Applications


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Communication Contract

ATM network

Communication ContractService Types

Parameter of Flow

Parameter of QoS

Contract

Contract


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Service 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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Course Outline

Chapter 1 Overview






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IPOA 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/IP Process

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

INARP in IPOANetwork ModelSVC


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mode

ATM NetworkARP Server

Ethernet

WAN

Router

INARP in IPOANetwork ModelPVC


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mode

ATM Network

Ethernet

WAN

Router

INARP i IPOA PVC M d


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INARP 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 upfirst. For example: Terminal A must set up a PVC to B in order to know

the IP address of B.

ARP i IPOA PVC M d


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ARP in IPOAPVC Mode

Terminal A 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 ...

ARP i IPOA PVC M d


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ARP in IPOAPVC Mode

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

the IPs of the computers that answered the InvATMARP will be set to the

map 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

ARP in IPOA PVC Mode


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ARP in IPOAPVC Mode

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

PVC

ATM 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

Course Outline


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Course Outline

Chapter 1 Overview





ATM in CDMA2000 BSS systemLarge


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y g

Capacity Configuration

Resource

Management &

Packet Processing

Subrack (CRPS)

Integrated

Processing

Subrack (CIPS)

Optical fiber or

several E1

cables

BTS

BTS baseband frame

service/ signal-in-band

AAL2 maintenance / signal-out-band AAL5

Abis interface:

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

Data Service

Processing

Subrack (CPMS)

Connected to

PDSN

Optic

fiber

Optic

fiber

Ethernet

cable

cBSC

Switch

Subrack

GPS/Glonass

receiver

Optic

fiber

Integrated

Management

Subrack (BAM)

ATM in CDMA2000 BSS SystemSmall


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Capacity Configuration

several E1cables

BTS

BTS baseband frame

service/ signal-in-band

AAL2 maintenance / signal-out-band AAL5

Abis interface:

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

Integrated

ManagementSubrack

(BAM)

Connected to

PDSN

cBSC

GPS/Glonass

Receiver

several E1

cables or

Optic fiber

Integrated

Processing

Subrack

Ethernet

cable

LAN

IMA Mode


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IMA 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 link could be transferred on several low speed physical links.

ATM Layer ATM Layer

Summary


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Summary

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 cell

header+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.

Questions


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Questions

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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Ora000008 Atm Principle (Bss) Issue3.0

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