atm-intro gen meir 0509
TRANSCRIPT
2 Confidential
N E T W O R K SSeminar Contents
Introduction to ATM
Adaptation Layers
Traffic Management
ATM Signaling
OAM
3 Confidential
N E T W O R K S
ATM Fundamental Concept
VoiceEnergy
Pause Pause Listening
Speaking Speaking
All communications are bursty
TimeTherefore, a high performance packet
switching network can carry allcommunications
4 Confidential
N E T W O R K S
ATM Vision: The Ultimate Integrated Services Network
ATMNetwork
Voice
Data Video
Video
Video
Voice
Voice
Data
Data
ATM network moves (fixed length packets) with low delay and low delay variation at high speedsDevices at ends translate (e.g., segment and reassemble) between cells and original traffic
5 Confidential
N E T W O R K STDM
TDM - Time Division Multiplexing A circuit switching technology Each channel has a fixed Time Slot (basic unit 64 kbit/s)
( for example: 30 TDM channels on one E1 trunk) Suitable for Circuit Switching technology
A circuit is established between the talks for the entire
duration of the call Fixed bit rate for any service
6 Confidential
N E T W O R K SATM
ATM - Asynchronous Transfer Mode A fastfast packet switching technology (cell = small packet, 48 bytes) Statistical multiplexing of several connections on the same link ATM Switch routes the user data (cells) to the next switch
using the VP, VC in the cell header Connection oriented
7 Confidential
N E T W O R K S
ATM Cell Structure(it all started with a single cell)
Header Payload
4 1 48 bytes
VCI
VCI
VPI
VPI
VCI PTI
HEC
CL
P
GFC
VPI - Virtual Path IdentifierVCI - Virtual Channel IdentifierGFC - Generic Flow Control
PTI - Payload Type IdentifierCLP - Cell Loss PriorityHEC - Header Error Check
NNI UNI
VCI
VCI
VPI
VPI
VCI PTI
HEC
CL
P
8 Confidential
N E T W O R K SATM Basic Features
Connection oriented mode
No control flow or error protection for connections
Limited functionality of cell header
Small and fixed payload size
9 Confidential
N E T W O R K S
Combinations of reserved VPI, VCI and PTI values
A - 0 or 1 depending on the specific function, C - Transmitted as 0, may be changed to 1 by the network
10 Confidential
N E T W O R K S
ATM Connection Identifiers
VC1
VC2VP1
VC1
VC2VP2
VC1
VC2VP1
VC1
VC2VP2
Link 1
VC1
VC2VP1
VC1
VC2VP2
VC1
VC2VP1
VC1
VC2VP2
A
BC
D
E
F
G
H
I
Network and SwitchesLink 1
Link 2 Link 2
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N E T W O R K S
Examples of VP and VCI Operations
ATMSwitch
VPI=20VCI=33 VPI=2
VCI=14
VPI=8VCI=56
ATMSwitch
VPI=5VCI=13
VPI=9VCI=27
VPI=4VCI=10
12 Confidential
N E T W O R K S
VP and VC Switching
VC1
VC2
VC1
VC2
VC4
VC3
VC1
VC2
VP Switch
VC Switch
VPI 4
VPI 11
VCI3
VCI2
VCI1
VCI4
VPI3’
VPI 5
VPI 3
VPI 2’
VPI 1’
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N E T W O R K S
Reserved VCIs at a UNI
VPI=0
VCI=35
VCI=45
Example of two VC services on VPI=0Only VCIs 35 and 45 are used for user data
}Reserved VCIs:VCI=5 for signaling, VCI=16 for ILMIVCI=3 and VCI=4 for F4 OAM
VPI=20
ActiveVCIs
unknown
Example of VP serviceNetwork knows nothing of whichVCIs are used for user data
} Standard VCIs that come with a VPIVCI=3 and VCI=4 for F4 OAM
VCIs 0-15 reserved for ITU-TVCIs 16-31 reserved for ATM Forum
15 Confidential
N E T W O R K S
V P L
Virtual Path and Channel Connections
VCL VCL VCL
ATM NE ATM NE
VCLsVCI = Virtual Channel IdentifierVCL = Virtual Channel LinkVCC = Virtual Channel Connection
VPI = Virtual Path IdentifierVPL = Virtual Path LinkVPC = Virtual Path Connection
V P L V P L V P L
VCCs ATM NE ATM NE
Virtual Channel Connections
Virtual Path Connections
17 Confidential
N E T W O R K SB-ISDN Reference Model
TC - Transmission Convergence SSCS - Service Specific Sub LayerPM - Physical Medium CPS - Common Part SublayerSAR - Segmentation And Reassembly
Convergence Layer
SAR LayerAAL
ATMCELL VPI/VCI translationCELL multiplex/demultiplexCELL HDR generation/extraction
CELL rate decoupling (idle cells)Cell delineationHDR HEC sequence (generation/recovery)
PMBIT TimingPhysical Medium
TC PhysicalLayer
SSCS
CPS
18 Confidential
N E T W O R K S
B-ISCN/ATM Layer and Sublayer Model
Layer name Functions performed
Higher layers Higher layer functions
AAL
ATM
LAYER
MANAGEMENT
ConvergenceSublayer (CS)
SAR Sublayer
Service Specific Sub Layer (SSCS)
Common Part Sublayer (CPS)
Segmentation and Reassembly
Generic flow controlCall header generation/extractionCell VCI/VPI translationCell multiplexingCell rate decoupling (unassigned Cells)
PHYS ICAL
TransmissionConvergence (TC)Sublayer
Physical mediumDependent (PMD)
Cell rate decoupling (idle cells)Cell delineationTransmission frame adaptationTransmission frame generation/ recovery
Bit timingPhysical medium
20 Confidential
N E T W O R K S
B-ISDN Protocol Reference Model
Signaling CO CLOther VBRServices
CBRServices
ATM
PHY
Convergence Sublayer (CS)
Segmentation and ReasssemblySublayer (SAR)
PlaneManagement
LayerManagement
Management Plane
AAL
ControlPlane
VBR Services
UserPlane
21 Confidential
N E T W O R K S
ATM Application Program Interfaces
F4, F5OAM
Q.2931
Q.2130
Q.2120
AAL5 AAL2 AAL1
ATM
PHY
MIBs
Planemanagement
Layer management
Overallmanagement
data
ATMOAMdata
Signalingcontrol
AAL message modestream mode,ILMI access
AAL CBRmode
ATMcell
accessATMAPI
AAL CBR/VBRmode
22 Confidential
N E T W O R K S
User plane higher-layer protocolsfor voice, video and WAN data
CircuitEmulation
Service(CES)
Voice &telephony
overATM
(VTOA)
Videoon
demand(VOD)
Framerelay
networkinterworking
Framerelay
serviceinterworking
ATMDXI and
FUNI
ATMaccess
toSMDS
AAL1 AAL2 AAL3/4AAL5
FR-SSCS
ATM layer
Physical layers
23 Confidential
N E T W O R K S
ATM Protocol Support for Voice and Video
CircuitEmulation
Serviceaf-vtoa-0078
Voice &telephony
overATM
af-vtoa-0089
VoiceTrunking over
ATM using AAL2af-vtoa-113.000
AAL1I.363.1
AAL2I.363.2
AAL5I.363.5
I. 366.2
ATM layerI.361
Physical layersG.804, I.432, UNI 3.1, T1.646
ResidentialBroadband
(RBB)
Video onDemand(VOD)
Other principle standardsUNI Signaling : Q.2931, UNI 3.1, UNI 4.0 (af-sig-0061.000)Signaling AAL: Q.2110, Q2130Traffic Management: I.371, af-tm-0056.000OAM: I.610NE Management: GR-CORE-1248
24 Confidential
N E T W O R K SRelationship of User and Network Layers
User User
ULP ULP
AALAAL
ATM ATM
PhysicalPhysical PhysicalPhysical
ATM
PhysicalPhysical
ATM
PhysicalPhysical
ATM
PhysicalPhysical
UNI NNI NNI UNI
ATM Network
25 Confidential
N E T W O R K S
Functional division of WAN ATM PDH
access system within ATM switch
SWITCHCORE
Addresstranslate
Policing& UPC
Trafficshaping
OAM
ATM
CELL
MUX
&
DEMUX
ATMcell
delin.+
HECgen.ITU
I.432
TXConv.ITU
G.804
OFF-THE-SHELFE1 FRAMERS
OFF-THE-SHELFT1 FRAMERS
OFF-THE-SHELFT3/E3 FRAMERS
SWITCHING ATM LAYER PMD LAYER
Dynamicswitching
Traffic handlingand signaling
Trafficdistribution
Mapping Transmission
Vendor specific:Shared memoryBus switchBanyan, input OR output buffered
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N E T W O R K S
State diagram for cell synchronization(“Direct HEC”)
SYNCPRE
SYNC
nconsecutive
incorrect HEC
mconsecutivecorrect HEC
Cell bycell
Incorrect HEC
Correct HEC
Bit by bit
HUNT
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N E T W O R K S
Automatic HEC model for ATM switching equipment
No bit error - No action
Single bit error- Error correction
Noerror- No
action
Multiple bit error- Cell is deleted
Errordetected- Cell isdeleted
Correctionmode
Detectionmode
30 Confidential
N E T W O R K S
ATM Multiplexing Function - the “Chopper”and the “Postman”
Data
VP1=0, VCI=51
H 48 B48 B48 B48 B
Voice
VP1=0, VCI=52
H 48 B48 B48 B48 B
Video
VP1=0, VCI=53
H 48 B48 B48 B48 B
PostmanChopper
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N E T W O R K S
ATM Multiplexing FunctionCell Scheduling by a “Gatekeeper” at the UNI
DataVC1=51
VoiceVC1=52
VideoVC1=53
Gatekeeper
Lowest priority
Highest priority
Next highest priority
32 Confidential
N E T W O R K S
Illustration of Virtual Channels SupportingMultimedia Application
H P H P H P H P H PVideo
H P H P H PVoice
H P H P H P H PData
Virtual Channel VPI=0, Vci=53 (Video)
Virtual Channel VPI=0, Vci=52 (Voice)
Virtual Channel VPI=0, Vci=51 (Data)
ATMMultiplexing
Function
Non real time variable bit rate (nrt-VBR)
Constant bit rate (CBR)
Real time variable bit rate (VBR)
User = Network Interface (UNI)
33 Confidential
N E T W O R K SIUB ATM
Active
VCs
Stand by
VCs
VP1
VC45
VC43
VC33
VC44
AAL5
AAL5
AAL5
AAL5
Q.2630
NBAP-Common
Mub-B
VC41 AAL0 Sync-B
NBAP-Dedicated
VC 39
VC38
VC36
VC32
VC34
VC37
AAL2
AAL5
AAL5
AAL5
AAL0
AAL5
User Plane
DCH, PCH, RACH, FACH
Q.2630
NBAP-Common
Mub-A
Synch-A
NBAP-Dedicated