09-ATM Pricinple-20090724-A
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Transcript of 09-ATM Pricinple-20090724-A
HUAWEI TECHNOLOGIES CO., LTD.
www.huawei.com
11.Dec,2006
HUAWEI Confidential
Security Level: Internal Use Only
xxxx ATM PrincipleISSUE2.0
HUAWEI TECHNOLOGIES CO., LTD. Page 2HUAWEI Confidential
The Asynchronous Transfer Mode (ATM) principle has dominated the telecom network for a long time as a mainstream datacom technology. Nowadays, the IP technology prevails over the telecom network. It is time for us to unveil the ATM principle thoroughly.
HUAWEI TECHNOLOGIES CO., LTD. Page 3HUAWEI Confidential
Upon the completion of the course, you can:
Describe the ATM cell
Master the VP switching and the VC switching
Master the ATM switching
Master the service type of the ATM
HUAWEI TECHNOLOGIES CO., LTD. Page 4HUAWEI Confidential
Chapter 1Chapter 1 ATM OverviewATM Overview
Chapter 2 ATMChapter 2 ATM ConceptsConcepts
Chapter 3 ATMChapter 3 ATM Protocol StacksProtocol Stacks
Chapter 4 ATMChapter 4 ATM Service and PropertiesService and Properties
HUAWEI TECHNOLOGIES CO., LTD. Page 5HUAWEI Confidential
What Is ATM?
ATM is an asynchronous transfer mode with cell as its unit. Asynchronism indicates that the information or cell flow from any user needs not to be periodical.
ATM integrates the advantages of the circuit switching and the packet switching. It carries various information media and communication services in a single backbone network, guarantees QoS, and meets the needs of the real-time service and non-real time service.
HUAWEI TECHNOLOGIES CO., LTD. Page 6HUAWEI Confidential
Differences Between ATM, Circuit Switching and Packet Switching
Circuit Switching
Connection oriented
Timeslot-oriented switching, line resources monopolization
Packet Switching
Connectionless oriented
Switching packets, sharing line resources
ATM : Asynchronous Transfer Mode
Connection oriented
Packet switching
HUAWEI TECHNOLOGIES CO., LTD. Page 7HUAWEI Confidential
Setup
Setup
Setup
Setup
Connectionless Network and Connection-Oriented ATM Network
Connectionless networkConnectionless, segment-by-segment forwarding The packet is too long and of unfixed length.The QoS of the network cannot be guaranteed.
Connection-oriented ATM network
Connection oriented, forwarding at high speed
The cell has a fixed length about 53 bytes
The QoS of the network can be guaranteed.
HUAWEI TECHNOLOGIES CO., LTD. Page 8HUAWEI Confidential
Organizations for Establishing the ATM Standards
ITU-T
Absorbs itself in standardizing ATM on the public network. Its representative
standards include the Q.2931/Q.2971, BISUP, and I.610.
ATM Forum
Absorbs itself in standardizing ATM on the private network and promoting the
ATM products and usage. Its representative standards include the UNI3.1,
UNI4.0, ILMI, PNNI, MPOA, VTOA, LANE, and TM4.0.
IETF
Absorbs itself in standardizing the IP over ATM and solving the bottleneck of
traditional routers. Its representative standards include the RFC1483,
RFC1577, IP Switch, and MPLS.
HUAWEI TECHNOLOGIES CO., LTD. Page 9HUAWEI Confidential
Chapter 1 ATM OverviewChapter 1 ATM Overview
Chapter 2 ATMChapter 2 ATM ConceptsConcepts
Chapter 3 ATMChapter 3 ATM Protocol StacksProtocol Stacks
Chapter 4 ATMChapter 4 ATM Service and PropertiesService and Properties
HUAWEI TECHNOLOGIES CO., LTD. Page 10HUAWEI Confidential
ATM Cell StructureGFC:Generic flow control (only valid in the UNI interface)VPI/VCI:Virtual path identifier/virtual channel identifierPT:Payload typeCLP:Cell lose priorityHEC:Header error identifier
ATM UNI UNI Cell ATM NNINNI Cell
48-byte load48-byte load
GFC (4)GFC (4)VPI (8)VPI (8)
VCI (16)VCI (16)
PTIPTI CLPCLP
HECHEC
48-byte load48-byte load
VPI (12)VPI (12)
VCI (16)VCI (16)
PTIPTI CLPCLPHECHEC
HUAWEI TECHNOLOGIES CO., LTD. Page 11HUAWEI Confidential
The VPI and the VCI are only locally valid.
ATM Connection
Virtual channel connection
Virtual path connection
VP switching
VCswitching
VC switching
NNI NNI
VPI = 2 VCI = 44
VPI = 1 VCI = 40
VPI = 3 VCI = 44
VPI = 4 VCI = 50
UNIUNI
AB C D
E
HUAWEI TECHNOLOGIES CO., LTD. Page 12HUAWEI Confidential
ATM virtual channel connection (VCC)
A VP contains VCs.A VCC contains VPs.
VC is the logical channel between the ATM nodes.
Virtual Channel (VC)
Virtual channel ( VC)
E3OC-3OC-12
Virtual path (VP)
Virtual path (VP)
The virtual identifier VPI/VCI.
VP and VC
HUAWEI TECHNOLOGIES CO., LTD. Page 13HUAWEI Confidential
VCI 1 VCI 2 VCI 3 VCI 4
VPI 2VPI 2VPI 3VPI 3VPI 1VPI 1
VPI 2VPI 2
VPI 3VPI 3
VPI 5
VPI 1VPI 1
VPI 4
Port 1
Port 2
Port 3
VCI 1VCI 2
VCI 1VCI 2
VP switching
VC switching
VCI 3
VCI 4
VCI 1
VCI 2
VP Switching and VC Switching
HUAWEI TECHNOLOGIES CO., LTD. Page 14HUAWEI Confidential
ATM Switching
ATM switching
PPHHYY
AATTMM
Port 3
PPHHYY
AATTMM
Port 4
PortPort VPIVPI VCIVCI
33 11 5151
44 33 3939
ATM layer
ATM switching
PPHHYY
AATTMM
Port 1
PPHHYY
AATTMM
Port 2
PortPort VPIVPI VCIVCI
11 22 3737
22 11 5151
ATM layer
PPHHYY
AATTMM
AAAALL
PPHHYY
AATTMM
AAAALL
VPI = 2 VCI = 37
VPI = 3 VCI = 39
NNI
UNI
UNI
HUAWEI TECHNOLOGIES CO., LTD. Page 15HUAWEI Confidential
ATM Connection Modes
PVC (permanent virtual channel): The NMS sets up
PVCs. Whether any service passes or any
terminal device is accessed, the PVCs are
always enabled till they are released by NMS.
PVCs are just like lease lines in the telephony
network.
SVC (switching virtual channel) : SVCs are set up and released by signaling. They are just like subscriber lines in the telephony network.
HUAWEI TECHNOLOGIES CO., LTD. Page 16HUAWEI Confidential
Chapter 1 ATM OverviewChapter 1 ATM Overview
Chapter 2 ATMChapter 2 ATM ConceptsConcepts
Chapter 3 ATMChapter 3 ATM Protocol StacksProtocol Stacks
Chapter 4 ATMChapter 4 ATM Service and PropertiesService and Properties
HUAWEI TECHNOLOGIES CO., LTD. Page 17HUAWEI Confidential
Reference Model of ATM Stacks
3 planes: user plane, control plane, and management plane
3 layers: physical layer, ATM layer, and ATM adaptation layer
Upper layer Upper layer
ATM layer
Physical layer
Control plane User plane
Management plane
ATM adaptation layer Layer-management
Plane-management
HUAWEI TECHNOLOGIES CO., LTD. Page 18HUAWEI Confidential
Functions of the ATM Layers
Convergence sublayer
Segmentation and reassembly cells
AAL
Generic traffic controlForm and pick up cell headersInterpret the VPI/VCI of cellsMultiplex and demultiplex cells
ATM layer
Decouple the cell rate, form/check the HEC sequence, delimitate cells, adapt/form/ restore the transmission frames.
Bit timing, physical media.
Voice cells
Video cells Data cells
Physical layer
TC
PM
SAR
CS
HUAWEI TECHNOLOGIES CO., LTD. Page 19HUAWEI Confidential
AAL Types and B-ISDN Service
Voice, video and circuit emulation service
Packet video Data Application
ATMservice
类AAL Type 1 Type 2 Type 3/4 Type 5
ATM layer
Physical layer
ATMnetwork
HUAWEI TECHNOLOGIES CO., LTD. Page 20HUAWEI Confidential
Flow for Processing the ATM CellsVoice, video, data, and images
AAL + ATM
ATM cell
Transmission processing
ATM cell
ATM cell Frame header and overhead
Physical medium processing
Frame to be transmitted
Physical interface
HUAWEI TECHNOLOGIES CO., LTD. Page 21HUAWEI Confidential
AAL
ATM
PH
IP
RFC1483
AAL
ATM
PH
Ethernet
RFC1483
Data Service on the ATM Network
RFC1483B encapsulation RFC1483R encapsulation
HUAWEI TECHNOLOGIES CO., LTD. Page 22HUAWEI Confidential
Chapter 1 ATM OverviewChapter 1 ATM Overview
Chapter 2 ATMChapter 2 ATM ConceptsConcepts
Chapter 3 ATMChapter 3 ATM Protocol StacksProtocol Stacks
Chapter 4 ATMChapter 4 ATM Service and PropertiesService and Properties
HUAWEI TECHNOLOGIES CO., LTD. Page 23HUAWEI Confidential
ATM Service Types
Constant bit rate (CBR) Constant bit rate service
Variable bit rate-real time (rt-VBR) Variable bit rate-real time service
VBR-non real time (nrt-VBR) VBR-non real time service
Unspecified bit rate (UBR) Unspecified bit rate service
Available bit rate (ABR) Available bit rate service
HUAWEI TECHNOLOGIES CO., LTD. Page 24HUAWEI Confidential
Traffic ParametersPCR Peak cell rate
SCR Sustainable cell rate
MCR Minimum cell rate
MBS Maximum burst size
HUAWEI TECHNOLOGIES CO., LTD. Page 25HUAWEI Confidential
CBR Service
Overhead
QoSTraffic parameter
Low High
Tolerance
1 byte
5-byte header
47-byte payload
Cell variationCell loss
PCR
Real time video and voice
HUAWEI TECHNOLOGIES CO., LTD. Page 26HUAWEI Confidential
VBR Service
QoSTraffic parameter
Low High
Tolerance
Cell variation (NRT)Cell variation (RT)
PCR
SCR
MBSCell loss
Packet voice and video
HUAWEI TECHNOLOGIES CO., LTD. Page 27HUAWEI Confidential
UBR Service
Public WAN
QoSTraffic parameter
Low High No guaranty of QoS
Tolerance
Cell lossCell variation
HUAWEI TECHNOLOGIES CO., LTD. Page 28HUAWEI Confidential
ABR Service
LAN
Overhead
. No celloverhead
. Uses congestionfeedbackinstead
5-byteheader
48-bytepayload
QoSTraffic parameter
Low High
PCR
MCR
Tolerance
Cell loss Cell variation
HUAWEI TECHNOLOGIES CO., LTD. Page 29HUAWEI Confidential
Questions
What are the functions of each byte in the ATM cell header?
How does the ATM switch switches the ATM cells? What services can the AAL1 and the AAL5 adapt respectively? What packets do the RFC1483B and the RFC1483R protocol encapsulate
respectively?
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