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Apendix
14 APPENDIX
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14 Apendix
APPENDIX 1
ATM
A short description of ATM follows that will give better
understanding on the ATM network. ATM can be traced back to
the early 1980s when operators were investigating the use of
Broadband ISDN for the transport of voice and data.
ITU-T (International Telecommunications Union-Telephony),
former CCITT, received a proposal from British Telecom,
France Telecom, Deutsche Telecom and AT&T for a new
transport mechanism, which was studied over the next four
years. The ATM standards were issued in 1989.
It became clear to a number of companies that ATM could
equally well be applied to the LAN environment. The ITU-T
was seen as an unsuitable vehicle for the development of ATM
technology. Thus, in 1991 the ATM Forum was formed. Nortel,
Sprint, Adaptive/NET and Cisco were involved in the formation
of the ATM Forum. Today over 1,000 interested companies and
organizations are involved in the implementation of ATM.
The ATM Forum generates recommendations and is considered
by many to be the de facto standards body for ATM.
ATM can be considered to be a connection-oriented way of
transporting different service classes of information, in fixed
length packages.
Error control of the header
53 bytes
LCN
Payload
Header
48 bytes
5 bytes
LCN: Logical Channel Number
ATM: Asynchronous Transfer Mode
Figure 14-1 The ATM cell
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The ATM cell is a small packet having a fixed length of 53
octets, five of which comprise the header. The remaining 48
octets make up the information field.
The 48 bytes in the payload were a size compromise between
the transport efficiency for data and the delay requirements for
voice and video traffic.
Having cells with a fixed length result in faster switching as no
additional software is required at the receiving end to determine
the cell length.
The function of ATM is to act as a transport mechanism for a
variety of services. One of the advantages of ATM is that it can
support many applications with high transmission speeds. ATM
transmission can be broken down into three main stages:
Constant
bit rate
Data
bursts
Variable
bit rate
Segmentation
Addressing
Multiplexing
Figure 14-2 ATM basics
Segmentation:
The incoming bit stream is firstly broken down into a fixed size
package of 48 bytes. This process is known as segmentation.
Addressing:
A 5-byte header is then added on to each chunk of 48 bytes. The
5 byte header contains the Logical Channel Number (LCN)
which is used to route the cell through the network.
Multiplexing:
Multiplexing is the final stage in ATM transmission where the
ATM cells are transmitted out on the physical line.
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14 Apendix
Different services require different transmission capabilities and
the ATM network will satisfy the specific characteristics and
needs of each service, either it is data or speech connection.
This is done with the aid of different classes.
Here the classes AAL1, AAL2 and AAL5 will be named and
shortly explained.
ATM PROTOCOL LAYERS
The information in the ATM network is transmitted with the aid
of ATM protocol stack, in order to take care of different types
of services. It consists of the following three layers:
•
The ATM adaptation Layer, AAL
•
The ATM layer
•
The Physical layer
Figure 14-3 below illustrates the three layers:
User data
Data packet
Segmented data packets
(length of segment: 48 octets)
AAL
Layer
ATM cells
(Payload+Header)
ATM
Layer
ATM cells in
an SDH frame
Physical
Layer
Figure 14-3 Protocol layers in ATM
•
The ATM Adaptation Layer, AAL.
The incoming information in to ATM network is chopped.
The bit stream is divided into 48-byte pieces in this layer.
This is also the layer responsible for specifying the class of
service.
•
The ATM layer.
Here the header is added or deleted to enable the cell to be
routed through the network based on the LCN.
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•
The physical layer.
It takes care of the mapping of the bits out to the physical
medium. Error checks on the cell header are also performed
on this layer.
The ATM Adaptation Layer
A number of AALs are required to cater for different services
such as voice and data, each of which has different
characteristics and hence places different bandwidth
requirements on the network. In addition to this, each of these
services will have a different quality of service associated with
them, which also must be catered for.
ATM Adaptation Layer 1, AAL1
AAL1 is used in the transport of connection oriented
synchronous services requiring a constant bit rate.
AAL1 is for example suitable for the transport of services such
as telephony and uncompressed video signals.
ATM adaptation layer 2, AAL2
AAL2 defines the transport of VBR real time traffic such as
compressed audio and video.
However, the development of UMTS has resulted in an
increased interest in AAL2 for the transport of real time traffic.
ATM adaptation layer 5, AAL5
AAL 5 is used in the transport of both connection oriented and
connectionless services. It is used for transmission of data (not
speech)
VIRTUAL PATH AND VIRTUAL CHANNEL
The ATM header contains the address field. Two of the main
components in the address field are the virtual path, VP, and the
virtual channel, VC. The ATM switch uses both of these
components to route the cell through the network.
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14 Apendix
48
VPI: Virtual Path Identifier
VCI: Virtual Channel Identifier
5
LCN
VCI
VPI
Virtual Channels
Virtual path
Physical link
Virtual path
Figure 10-4 Virtual Path and Virtual Channel
The Logical Channel Number (LCN) in the header contains the
VPI / VCI values. The VPI and VCI values together, indicate a
specific connection for one unique call on a specific physical
interface between two nodes in an ATM network.
Switching via the ATM transport network is done with the aid
of VP and VC.
The SVC (Switched Virtual Connection) is a connection
established by signaling initiated by the end user.
A routing table is used to control the switching process in the
network. The routing table itself is updated by means of
signaling.
An ATM switch is essentially a simple hardware device with a
lookup table and an output queue for each port. The header of
the incoming cell contains the VPI and VCI values. The switch
looks up the values in the table and routes the cell to the
appropriate cell queue on a physical port where it is allocated a
VPI and VCI value for the outgoing connection.
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APPENDIX 2
ABBREVIATIONS
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AAL
ACC
ACC
ACS
ADP
ADM
AHT
AIP
ALI
AMI
AMR
AMU
ANSI
AON
APS
ASC
AUC
APG
AP/SP
APM
AM
APSI
AST
ATM
ATM Adaptation Layer
Automated Collected Call or
Account card calling
Adjunct computer subsystem
Alphanumeric Device Protocol
Add/Drop Multiplexor
Average Hold Times
Advanced IP
ATM Link Interface
Alternate Mark Inversion
Adaptive Multi Rate
Automatic Maintenance Unit
American National Standards Institute
Automatic identification Of calling subscriber Number
Automatic Protection Switching
Access screening
Authentication Centre
Adjunct Processor Group
Adjunct or Support Processor
Adjunct Processor Module
Application Modularity
Application Platform Service Interface
Announcement Services Terminal
Asynchronous Transfer Mode
BN
BSC
BYB 202
BYB 501
B8ZS
Block Number
Base Station Controller
AXE Building Practice
AXE Building Practice
Binary Eight Zeros Substitution
CAS
CAT
CATV
CBC
CCD
CCS
CDB
CDM
CGB
CHSS
CIS
CL
CLM
CMI
Channel-Associated Signaling
Code Answer and Tone Sender
Cable TV
Central Building Clock
Conference Call Device
Common Channel Signaling Subsystem
Clock Distribution Board
Clock Distribution Magazine
Clock Generation Board
Charging Service Subsystem
Clock Interrupt Signal
Clock
Clock Module
Code Mark Inversion
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14 Apendix
COMRM
COMS
CONRM
COSS
CP
CPS
CR
CRC
CSFSKD
CSKD
CSR
CT
Communication RM
Communication Subsystem
Connection RM
Connection Service Subsystem
Central Processor
Central processor subsystem
Clock Reference
Cyclic Redundancy Check
Code Sender FSK Device, FSK meaning Frequency Shift Keying
Code Sender Key-set Device
Code Sender and Receiver
Control type
D-AMPS
DCME
DCS
DIP
DL
DL2
DL3
DL5
DL34
DL5
DLEB
DLHB
DLNB
DM
DS
DSA
DTI
DTMF
Digital advanced mobile phone system
Digital Circuit Multiplication Equipment
Data communications subsystem
Digital Path
Digital Link
Digital Link #2 (a link carrying 32 multiple positions)
Digital Link # 3 (a multiplexed link carrying 16 DL2s =512 Time Slots)
Digital Link # 5 (a multiplexed link carrying 512 DL2s)
Digital Link # 34 (a multiplexed link carrying from 4 to 84 DL2s that means
128 – 2096 Time Slots)
Digital Link # 5, that means, a multiplexed link carrying 8k Time Slots.
Digital Link Multiplexer for existing equipment board
Digital Link Multiplexer half-size board
Digital Link Multiplexer for NNRP board
Data Module
Data Store
Dynamic Size Alteration
Data Transmission Interworking unit
Dual Tone Multi Frequency Signaling
EC
ECP
E-DB
EFR
EMC
EMB
EMG
EMRPI
EPSB
ESF
ESS-R
ET
ETC
ETSI
Echo Canceller
Echo Cancellers in pool
External database
Enhanced Full Rate
Electro-Magnetic Compatibility
Extension Module Bus
Extension Module Group
Extension Module Regional Processor Integrated
Ethernet Packet Switch Board
Extended Super Frame
Extended Switching Subsystem
Exchange Terminals
Exchange Terminal Circuit
European Telecommunication Standards Institute
FH
FID
FPH
FR
Frame Handler
Forlopp identity
Freephone
Full Rate
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FOS
FMI
FTP
FMS
Formatting and Output Subsystem
File Management Interface
File Transfer Protocol
File management subsystem
GCME
GDM
GEM
GLR
GMSC
GS
GS16M
GSS
GSC
GSS
GSM
GSM Circuit Mulitiplexing Equipment
General Device Magazine
Generic Ericsson Magazine
Gateway Location Register
Gateway MSC
Group Switch
Group Switch 16K magazine
Group Switching Subsystem
GPS System Clock
Group Switching Subsystem
Global System Mobile
HW
HLR
HR
HWI
Hardware
Home Location Register
Half Rate
HighWay Interface
IAS
IETF
IFC
ILR
I/O
IOG
IP
IPAR
IPC
IPN
IPU
IRB
ISDN
ISP
ISP
ITU-T
IVPN
IVR
IWU
Internet Access Server
Internet Engineering Task Force
Incoming Clock Function
Inter-working Location Register
Input/Output
Input/Output Group
Intelligent peripheral
Individual Parameter Setting
Inter Processor Communication
Inter Platform Network
Instruction processor unit
Incoming Reference Board
Integrated Services Digital Networks
Internet Service Provider or
Improved in-Service Performance
International Telecommunication Union – Telecommunications
Standardization Sector
International Virtual Private Network
Interactive Voice Response
Interworking Unit
JTP
Job Transfer Protocol
KRD
Key-set Receiver Device
LAPD
LED
LRB
LM
Link Access Protocol Digital
Light Emitting Diode
Local Reference Board
Logic Module
MAI
Maintenance Unit Interface
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MAS
MAU
MCS
M-AST
MCC
MF
MFP
MGC
MGW
MS
MSP
MTAP
MUP
MV
MVPN
Maintenance subsystem
Maintenance unit
Man-machine communications subsystem
Modula AST(Announcement Service Terminal)
Mobile Crosstalk Control
Multi Frequency
Multi Frequency Pulse
Media Gateway Controller
Media Gateway
Multiplex Section
Multiplexor Section Protection MSC
Mobile Switching Center
Message protocol to Adjunct Processor
Multiple Position
Majority Vote
Cellular virtual private network
NAPRM
NE
NICC
NNRP
NMT
NP
NS
Network Access Products RM
Network Element
Network intelligence call centre
Network Node Renewal Process
Nordic Mobile Telephony
Number portability
Network Synchronization
OCS
OC-3
OH
OMRM
OMS-R
ONG
OPS
Open Communication Subsystem
Optical Container level 3
Over Head
Operation and Maintenance RM
Operation and Maintenance Subsystem
Open Network Gateway
Operator Subsystem
PCD-G
PCU
PDC
PDSPL
PDH
PDRM
PLMN
PN
POP
PPS
PRA
PRM
PS
PSTN
POWC
Pulse Code Device – Generic
Packet Control Unit
Personal Digital Cellular
Pooled Digital Signaling Platform - Loadable
Plesiochronous Digital Hierarchy
Pooled Devices RM
Public Land Mobile Network
Personal number
Point-of-Presence.
Prepaid service
ISDN Primary Rate Access
Premium rate
Program Store
Public Switched Telephone Network
Power Control Unit
RCM
RCM-E
RFI
RLL
RMP
Reference Clock Module
RCM - version E
Ready For Installation
Radio in the Local Loop
Resource Module Platform
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RM
RMS
RPB
RPH
RPx
RP4
practice
RPB-S
RPG-3
RPI
RPP
RPS
RS
Resource Module
Remote Measurement System
Regional Processor Handler
Regional Processor Bus,
Regional Processor.....
Regional Processor # 4, that means, adapted to the BYB 501 equipment
SAAL
SCB
SCP
SCP
SCFAM
SCB-RP
SDH
SDP
SDT
SDXC
SIB
SN
SN
Signaling ATM Adaptation Layer
Support and Connection Board
Service Control Point
Service Control Function
Service control function application module
Support and Connection Board – with an RP
Synchronous Digital Hierarchy
Service data point
System Down Time,
Synchronous Digital Cross Connect
Service Independent Building block
Signal Number or
Service control Node
SMAS
SNT
SONET
SP
SPE
SPM
SPG
SPS
SPU
SSFAM
Service Management Application System (
Switching Network Terminal
Synchronous Optical Network
Support Processor
Synchronous Payload Envelope
Space Switch Module
Support processor group
Support processor subsystem
Signal processor unit
Service switching function application module
SSM
SSCP
SSP
SSF
SG
SGU
SSL
STOC
STM-1
STC-G
STP
STS
STS-3
Synchronization Status Message
Service Switching and Control Point
Service Switching Point
Service Switching
Signaling Gateway
Signaling Gateway Unit
Service Script Logic
Signaling Terminal Open Communication
Synchronous Transport Module – level 1
Signaling Terminal Central – Group Switch connected
Signaling Transfer Point
Statistics and Traffic Measurement Subsystem
Synchronous Transport Signal level 3
Serial Regional Processor Bus
Regional Processor, GS-connected, 3rd generation
Regional Processor Imbedded (also referred to as the micro-RP)
Regional Processor Platform
Regional processor subsystem
Reference Store
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14 Apendix
SW
Software
TDMA
TMN
Time Division Mobile System
Transport Management Network
TACS
TCD
TCS
TCP/IP
TMOS
TRA
TRC
TRH
TRU
TS4B
TS
TSM
TTA
Total Access Communications System
Tone Continuity Device
Traffic Control Subsystem
Transmission Control Protocol/Internet Protocol
Telecommunications Management and Operations Support system
Transcoders
Transcoder Controller
Transaction Record Handler protocol
Tone Receiver Unit
Time Switch Board with 4 TSM functions
Time Slot
Time Switch Module
Test Telephone Access
UAN
UPT
universal access number
Universal Personal Telecommunications
VC
VOT
VoIP
VMSC
VPN
VPSM
VT
Virtual Container
Televoting
Voice over IP,
Visited Mobile Services Switching Center
Virtual Private Network
Virtual Port Service Manager
Virtual Tributary
XDB
XM
XNB
XSS
Switch Distributed Board
Switch Matrix Unit
Switch Board for NNRP
eXisting Source System
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14 Apendix
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