Download presentation
Presentation is loading. Please wait.
1
CSC 581 Communication Networks II
Chapter 9: ISDN and ATM Dr. Cheer-Sun Yang
2
Topics ISDN BISDN ATM
3
ISDN ISDN Services ISDN Architecture Protocols: SS7 and ISDN Protocols
BISDN
4
ISDN Services Integrated voice and data applications
Example: Teleconferencing Computer and telephone can combine.
5
ISDN Architecture Basic rate (2B + D): 2 D channels and 1 D channel
Prime rate (23B + D): 23 B channels and 1 D channel
6
Signaling System No 7 SS7 is used for controlling the signaling of voice data communication. X.25 cannot support more advanced telephone services such as caller ID, 3-way calling, call forwarding, calling card, etc. SS7 provides a common-channel signaling feature for supporting these advanced telephone services. Common channel signaling is an out-of band signaling technique for which signaling information is transmitted using an extra channel beyond the voice data channel.
7
SS7 Layers
8
ATM Asynchronous Transfer Mode NOT the Auto-Teller Machine in a bank
Cell Switching technique using a fixed-size cell as the data unit.
9
Benefits of Small Fixed-Size Cells
Easier to program. Faster transmission time for each cell. Easier to overlap input and output operations. Smaller outgoing buffer Switches can forward multiple packets concurrently.
10
Protocol Architecture
Similarities between ATM and packet switching Transfer of data in discrete chunks Multiple logical connections over single physical interface In ATM flow on each logical connection is in fixed sized packets called cells NNI and UNI Minimal error and flow control Reduced overhead Data rates (physical layer) 25.6Mbps to Mbps
11
Management plane Plane management Control plane User plane
Layer management Higher layers Higher layers ATM adaptation layer ATM layer Physical layer Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.2
12
Protocol Architecture (diag)
13
Reference Model Planes
User plane Provides for user information transfer Control plane Call and connection control Management plane Plane management whole system functions Layer management Resources and parameters in protocol entities
14
5 Bytes 48 Bytes Header Payload
Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.1
15
Bursty variable-length packets
Voice A/D AAL cells s1 , s2 … Digital voice samples Video A/D … Compression AAL cells compressed frames picture frames Data AAL cells Bursty variable-length packets Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.3
16
… User information User information End system Network End system AAL
ATM ATM ATM ATM PHY PHY PHY PHY … End system Network End system Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.4
17
X X X X X X X X X Private ATM network Private UNI Private NNI
Public UNI Public ATM network A X X NNI Public UNI X B-ICI Public ATM network B X Public UNI X X Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.5
18
ATM layer Physical layer Physical medium
Transmission convergence sublayer Physical layer Physical medium dependent sublayer Physical medium Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.6
19
GFC (4 bits) VPI (4 bits) VPI (4 bits) VCI (4 bits) ATM cell header
PT (3 bits) CLP (1 bit) HEC (8 bits) Payload (48 bytes) Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.7
20
probability density D0 Peak-to-Peak CDV Dmax
Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.8
21
AAL Layer Service Specific Convergence Sublayer
Convergence Sublayer Common Part AAL Layer Segmentation and Reassembly Sublayer Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.9
22
Higher layer User data stream … Convergence sublayer CS PDUs SAR PDUs
b b b3 … Convergence sublayer CS PDUs 47 47 47 SAR PDUs SAR sublayer H H H ATM Cells H H ATM layer H Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.10
23
(b) CS PDU with pointer in structured data transfer
(a) SAR PDU header CSI Seq. Count SNP 1 bit bits bits (b) CS PDU with pointer in structured data transfer 47 Bytes AAL 1 Pointer 1 Byte 46 Bytes Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.11
24
Mobile switching office
AAL 2 Mobile switching office ATM cells Low bit rate Short voice packets Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.12
25
This example assumes 24 byte packets
Higher layer This example assumes 24 byte packets P1 P2 P3 Service specific convergence sublayer Assume null Common part convergence sublayer H H Add 3-byte header to each user packet H SAR sublayer Segment into SAR PDUs PAD H ATM layer H Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.13
26
(a) CPS packet structure
CID (8 bits) CPS packet header PPT (2 bits) LI (6 bits) UUI (3 bits) HEC (5 bits) Payload Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure Part 1
27
(b) ATM SDU Cell Header Start field (STF) OSF (6 bits) CPS-PDU payload
SN (1 bit) P (1 bit) Start field (STF) OSF (6 bits) CPS-PDU payload PAD Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure Part 2
28
… … Higher layer Service specific convergence sublayer
Information User message Service specific convergence sublayer Assume null Common part convergence sublayer Pad message to multiple of 4 bytes. Add header and trailer. H Information PAD T 4 4 Each SAR-PDU consists of 2-byte header, 2-byte trailer, and 44-byte payload. SAR sublayer … … ATM layer Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.15
29
1 1 2 1 - 65,535 0-3 1 1 2 (bytes) (bytes) (bytes)
(a) CPCS-PDU format Header Trailer CPI Btag BASize CPCS - PDU Payload Pad AL Etag Length , (bytes) (bytes) (bytes) (b) SAR PDU format Trailer (2 bytes) Header (2 bytes) ST SN MID SAR - PDU Payload LI CRC (bits) (bytes) (bits) Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.16
30
Service specific convergence sublayer
Higher layer Assume two packets from different users P1 P2 Service specific convergence sublayer MID = a MID = b Common part convergence and SAR sublayers Each packet is segmented separately. SAR PDUs identified by MID. CPCS SAR CPCS SAR SPDUA2 SPDUA1 SPDUB2 SPDUB1 Interleaver Interleaved cells Cells from two packets are interleaved. ATM layer Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.17
31
… … Higher layer Service specific convergence sublayer
Information Service specific convergence sublayer Assume null Common part convergence sublayer Information PAD T SAR sublayer … 48 (0) 48 (0) 48 (1) … ATM layer PTI = 0 PTI = 0 PTI = 1 Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.18
32
Information UU CPI Length CRC 0 - 65,535 0-47 1 1 2 4 (bytes) (bytes)
Pad UU CPI Length CRC 0 - 65, (bytes) (bytes) Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.19
33
Signaling application
Message Message SSCF maps SSCOP service to service required by SSCF user SSCF SSCS SSCOP identifies gaps in SDU sequence and requests retransmissions SSCOP Message T AAL 5 provides non-assured service CSCP and SAR of AAL 5 As per Figure 9.18 … ATM layer Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.20
34
0 - 65,535 0-3 2 2 4 24 (bytes) (bytes)(bits)(bits) (bits) (bits)
PL RSVD PDU SN Type Information Pad 0 - 65, (bytes) (bytes)(bits)(bits) (bits) (bits) Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.21
35
(a) DCC ATM format AFI DCC HO-DSP ESI SEL IDP DSP IDI
AFI DCC HO-DSP ESI SEL IDP DSP IDI (b) ICD ATM format AFI ICD HO-DSP ESI SEL IDP DSP IDI (c) E.164 ATM format AFI E HO-DSP ESI SEL IDP DSP IDI Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.22
36
Source Network Destination UNI UNI
SETUP CALL PROCEEDING SETUP CALL PROCEEDING CONNECT CONNECT CONNECT ACK CONNECT ACK RELEASE RELEASE COMPLETE RELEASE RELEASE COMPLETE Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.23
37
Network A Network B PNNI PNNI
Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.24
38
Source Switch Transit Switch Destination Switch Source A Destination B
SETUP SETUP SETUP CALL PROCEEDING SETUP CALL PROCEEDING CALL PROCEEDING CALL PROCEEDING CONNECT CONNECT CONNECT CONNECT CONNECT ACK CONNECT ACK CONNECT ACK CONNECT ACK RELEASE RELEASE RELEASE COMPLETE RELEASE RELEASE COMPLETE RELEASE RELEASE COMPLETE RELEASE COMPLETE Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.25
39
Logical Link A B Logical Group Node Peer Group Leader PG(A) A.2 A.1
PG(B) PG(A.2) PG(A.1) A.2.2 B.1 A.1.2 B.3 A.2.3 A.2.1 A.1.3 A.2.4 B.2 A.1.1 B.4 Physical Link Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.26
40
A.2 B A.1.2 A.1.1 A.1.3 Copyright 2000 McGraw-Hill Leon-Garcia and Widjaja Communication Networks Figure 9.27
41
ATM Logical Connections
Virtual channel connections (VCC) Analogous to virtual circuit in X.25 Basic unit of switching Between two end users Full duplex Fixed size cells Data, user-network exchange (control) and network-network exchange (network management and routing) Virtual path connection (VPC) Bundle of VCC with same end points
42
ATM Connection Relationships
43
Advantages of Virtual Paths
Simplified network architecture Increased network performance and reliability Reduced processing Short connection setup time Enhanced network services
44
Virtual Channel Connection Uses
Between end users End to end user data Control signals VPC provides overall capacity VCC organization done by users Between end user and network Control signaling Between network entities Network traffic management Routing
45
VP/VC Characteristics
Quality of service Switched and semi-permanent channel connections Call sequence integrity Traffic parameter negotiation and usage monitoring VPC only Virtual channel identifier restriction within VPC
46
Control Signaling - VCC
Done on separate connection Semi-permanent VCC Meta-signaling channel Used as permanent control signal channel User to network signaling virtual channel For control signaling Used to set up VCCs to carry user data User to user signaling virtual channel Within pre-established VPC Used by two end users without network intervention to establish and release user to user VCC
47
Control Signaling - VPC
Semi-permanent Customer controlled Network controlled
48
ATM Cells Fixed size 5 octet header 48 octet information field
Small cells reduce queuing delay for high priority cells Small cells can be switched more efficiently Easier to implement switching of small cells in hardware
49
ATM Cell Format
50
Header Format Generic flow control Virtual path identifier
Only at user to network interface Controls flow only at this point Virtual path identifier Virtual channel identifier Payload type e.g. user info or network management Cell loss priority Header error control
51
Generic Flow Control (GFC)
Control traffic flow at user to network interface (UNI) to alleviate short term overload Two sets of procedures Uncontrolled transmission Controlled transmission Every connection either subject to flow control or not Subject to flow control May be one group (A) default May be two groups (A and B) Flow control is from subscriber to network Controlled by network side
52
Single Group of Connections (1)
Terminal equipment (TE) initializes two variables TRANSMIT flag to 1 GO_CNTR (credit counter) to 0 If TRANSMIT=1 cells on uncontrolled connection may be sent any time If TRANSMIT=0 no cells may be sent (on controlled or uncontrolled connections) If HALT received, TRANSMIT set to 0 and remains until NO_HALT
53
Header Error Control 8 bit error control field
Calculated on remaining 32 bits of header Allows some error correction
54
Cell Based Physical Layer
No framing imposed Continuous stream of 53 octet cells Cell delineation based on header error control field
55
Cell Delineation State Diagram
56
SDH Based Physical Layer
Imposes structure on ATM stream e.g. for Mbps Use STM-1 (STS-3) frame Can carry ATM and STM payloads Specific connections can be circuit switched using SDH channel SDH multiplexing techniques can combine several ATM streams
57
STM-1 Payload for SDH-Based ATM Cell Transmission
58
ATM Service Categories
Real time Constant bit rate (CBR) Real time variable bit rate (rt-VBR) Non-real time Non-real time variable bit rate (nrt-VBR) Available bit rate (ABR) Unspecified bit rate (UBR)
59
Real Time Services Amount of delay Variation of delay (jitter)
60
CBR Fixed data rate continuously available Tight upper bound on delay
Uncompressed audio and video Video conferencing Interactive audio A/V distribution and retrieval
61
rt-VBR Time sensitive application
Tightly constrained delay and delay variation rt-VBR applications transmit at a rate that varies with time e.g. compressed video Produces varying sized image frames Original (uncompressed) frame rate constant So compressed data rate varies Can statistically multiplex connections
62
nrt-VBR May be able to characterize expected traffic flow
Improve QoS in loss and delay End system specifies: Peak cell rate Sustainable or average rate Measure of how bursty traffic is e.g. Airline reservations, banking transactions
63
UBR May be additional capacity over and above that used by CBR and VBR traffic Not all resources dedicated Bursty nature of VBR For application that can tolerate some cell loss or variable delays e.g. TCP based traffic Cells forwarded on FIFO basis Best efforts service
64
ABR Application specifies peak cell rate (PCR) and minimum cell rate (MCR) Resources allocated to give at least MCR Spare capacity shared among all ARB sources e.g. LAN interconnection
65
ATM Adaptation Layer Support for information transfer protocol not based on ATM PCM (voice) Assemble bits into cells Re-assemble into constant flow IP Map IP packets onto ATM cells Fragment IP packets Use LAPF over ATM to retain all IP infrastructure
66
ATM Bit Rate Services
67
Adaptation Layer Services
Handle transmission errors Segmentation and re-assembly Handle lost and misinserted cells Flow control and timing
68
Supported Application types
Circuit emulation VBR voice and video General data service IP over ATM Multiprotocol encapsulation over ATM (MPOA) IPX, AppleTalk, DECNET) LAN emulation
69
AAL Protocols Convergence sublayer (CS)
Support for specific applications AAL user attaches at SAP Segmentation and re-assembly sublayer (SAR) Packages and unpacks info received from CS into cells Four types Type 1 Type 2 Type 3/4 Type 5
70
AAL Protocols
71
Segmentation and Reassembly PDU
72
AAL Type 1 CBR source SAR packs and unpacks bits
Block accompanied by sequence number
73
AAL Type 2 VBR Analog applications
74
AAL Type 3/4 Connectionless or connected Message mode or stream mode
75
AAL Type 5 Streamlined transport for connection oriented higher layer protocols
76
Reading Chapter 9 ATM Forum Web site Frame Relay forum
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.