ora000008 atm principle (bss) issue3.0
TRANSCRIPT
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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
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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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
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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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
QoSTraffic parameter
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
QoSTraffic parameter
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
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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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
Chapter 2 Basic Concepts of ATM
Chapter 3 ATM Protocol & Service Type
Chapter 4 Basic Concepts of IPOA
Chapter 5 ATM in CDMA2000 BSS
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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