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Introduction to ATM

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					               Introduction
               to ATM


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NW98_US_811                   1
           Agenda
               • Introduction
               • ATM Fundamentals
                 Rudimentary ATM Concepts
                 ATM Reference Model
                 ATM Service Categories
                 Traffic Management
               • ATM Transport Standards
               • Campus ATM Internetworking
               • Wrap Up
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NW98_US_811                                   2
           Characteristics of ATM
               Voice

               Data

               Video                    Cells



                • Uses small, fixed-sized cells
                • Connection-oriented
                • Supports multiple service types
                • Applicable to LAN and WAN

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NW98_US_811                                         3
           Campus Networking Evolution
                             Traditional Network
                   Shared
          Ethernet Clients



                                                       Corporate WAN
       Local                                            and Internet
   Workgroup
     Servers



                                    • Hierarchical design
                                      with broadcast control
                                    • 80/20 rule
                                    • Homogenous user communities
                                    • Moves, adds, and changes manually
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NW98_US_811                                                            4
           Campus Networking Evolution
                      Contemporary Network
   Switched
   Ethernet  Ethernet Switch
    Clients with VLAN Support
                                                            Corporate WAN
                                                            and Internet
                                  Campus
                                ATM Network
                                                            Centralized
                                                            High-Performance
                                  ATM-Attached              Servers
                                    Station(s)


                  •   Network hierarchy maintained
                  •   Traffic patterns migrating
                  •   Client and server performance increases
                  •   Moves, adds, and changes automated
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NW98_US_811                                                                 5
           The Wonderful World of Acronyms
               AAL—ATM Adaptation Layer
               AAL1—See CBR
               AAL2—See VBR
               AAL3/4—See UBR
               AAL5—See ABR
               ABR—Available Bit Rate
               API—Application Programmer Interface
               B-ICI—B-ISDN Inter-Carrier Interface
               BUS—Broadcast and Unknown Server
               CAC—Connection Admission Control
               CBR—Constant Bit Rate
               CCITT—Consultative Committee for International Telephony and Telegraph
               CDVT—Cell Delay Variation Tolerance
               CLP—Cell Loss Priority
               CLR—Cell Loss Ratio
               CS—Convergence Sublayer
               EFCI—Explicit Forward Congestion Indicator
               ELAN—Emulated LAN
               GCRA—Generic Cell Rate Algorithm
               GFC—Generic Flow Control
               HEC—Header Error Check
               IISP—Interim Inter-Switch Signaling Protocol
               ILMI—Interim Local Management Interface
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NW98_US_811                                                                             6
           The Wonderful World of Acronyms
                IPD—Intelligent Packet Discard
                LANE—Local Area Network Emulation
                LEC—LAN Emulation Client
                LES—LAN Emulation Server
                LECS—LAN Emulation Configuration Server
                LIS—Logical IP Subnet
                MBS—Maximum Burst Size
                MCR—Minimum Cell Rate
                MCTD—Maximum Cell Transfer Delay
                MPC—MPOA Client (aka Edge Device)
                MPOA—Multi-Protocol Over ATM
                MPS—MPOA Server (aka Router Server)
                NNI—Network-to-Network Interface
                OC—Optical Carrier
                PCR—Peak Cell Rate
                PMD—Physical Media Dependent
                PNNI—Private Network-to-Network Interface
                PTI—Payload Type Identifier
                PVC—Permanent Virtual Circuit
                Q.SAAL—aka Q.2100—Signaling ATM Adaptation Layer
                RFC1483—Multiprotocol Encapsulation over AAL5
                RFC1577—Classical IP and ARP over ATM
                RM—Resource Management
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NW98_US_811                                                        7
           The Wonderful World of Acronyms
                 SAR—Segmentation and Reassembly
                 SDH—Synchronous Digital Hierarchy
                 SONET—Synchronous Optical Network
                 STM—Synchronous Transport Mode
                 STS—Synchronous Transport Signal
                 SCR—Sustained Cell Rate
                 SVC—Switched Virtual Circuit
                 SSCOP—Signaling Specific Convergence Protocol
                 TC—Transmission Convergence
                 UBR—Unspecified Bit Rate
                 UNI—User-to-Network Interface
                 UPC—Usage Parameter Control
                 VBR-NRT—Variable Bit Rate-Non-Real Time
                 VBR-RT—Variable Bit Rate-Real Time
                 VC—Virtual Circuit (or sometimes Virtual Connection)
                 VCC—Virtual Channel Connection
                 VCI—Virtual Channel Identifier
                 VC Switch—Virtual Circuit Switch
                 VP—Virtual Path
                 VPC—Virtual Path Connection
                 VPI—Virtual Path Identifier
                 VP Switch—Virtual Path Switch
                 VS/VD—Virtual Source/Virtual Destination
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NW98_US_811                                                             8
           Agenda
               • Introduction
               • ATM Fundamentals
                 Rudimentary ATM Concepts
                 ATM Reference Model
                 ATM Service Categories
                 Traffic Management
               • ATM Transport Standards
               • Campus ATM Internetworking
               • Wrap Up
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NW98_US_811                                   9
           Rudimentary ATM Concepts


                 • Physical layer
                 • Signaling
                 • Cell format
                 • Connection types


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NW98_US_811                           10
           ATM Transmission Media
                 ATM SDH/SONET Rates Chart
                       SDH           SONET      Rate—Mbps
                                  STS-1/OC-1       51.84
                      STM-1       STS-3/OC-3       155.52
                      STM-4      STS-12/OC-12      622.08
                     STM-8       STS-24/OC-24     1,244.16
                     STM-16      STS-48/OC-48     2,488.32

               • CCITT (Consultative Committee for International
                 Telephony and Telegraph)
               • ITU (International Telecommunications Union)
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NW98_US_811                                                        11
           ATM Physical Interface Rates
    Framing           Data                                Media
                      Rate
                                 Multi-   Single-   Coaxial   UTP–5   UTP–3   STP
                     (Mbps)      Mode      Mode      Cable
                                 Fiber     Fiber
    DS1              1.544                                                    (TP)
      E1             2.048
      J2             6.23                                                     (TP)
    DS3               45
      E3              34
      E4              139                             X
    ATM25             25.6
    STS 1             51.8
    STS3c/STM1        155                                              X
    STS 12c/STM4      622
    4B/5B (TAXI)      100
    8B/10B            155
    (Fiberchannel)


         = Standardized      X = Proposed/In Progress

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NW98_US_811                                                                          12
           Rudimentary ATM Concepts


                 • Physical layer
                 • Signaling
                 • Cell format
                 • Connection types


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NW98_US_811                           13
           ATM Building Blocks


                    • ATM signaling
                      UNI and NNI

                    • Virtual connections
                      VCC, VP, and VC




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NW98_US_811                                 14
           ATM Signaling
                                Public UNI

                                                        Public ATM Network
                                                                             B-ICI
                  UNI
                                              NNI




                          NNI
                                                                Public ATM Network
               Token
                Ring
                                               NNI
                                  Private ATM Network


                 • UNI = User-to-Network Interface
                 • NNI = Network-to-Network Interface
                 • Cell header content varies depending
                   on who‘s talking to whom
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NW98_US_811                                                                      15
           Virtual Path and Virtual Channels
                                                                  Virtual Channels (VC)


                       ATM Physical Link              Virtual Path (VP)
               Virtual Channel Connection (VCC)

                             E3
                            OC–12                     Virtual Path (VP)


                                                                  Virtual Channels (VC)




                                                                    Virtual Channel
   Virtual Channel Connection           Virtual Path
                                                                          (VC)
              (VCC)                         (VP)
                                                                     Logical Path
      Contains Multiple VPs         Contains Multiple VCs
                                                                Between ATM End Points

                          Connection Identifier = VPI/VCI
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NW98_US_811                                                                               16
           ATM Switches
                    Input        Output
               Port VPI/VCI Port   VPI/VCI                 45

                1       29   2       45                2
                                             29   64
                2       45   1       29           1
                1       64   3       29                3
                3       29   1       64                    29


               • ATM switches translate VPI/VCI values
               • VPI/VCI value unique only per interface—
                 e.g.: locally significant and may be re-used
                 elsewhere in network
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NW98_US_811                                                     17
           VP and VC Switching
        VC Switch

                                 VCI 1           VCI 2      VCI 3      VCI 4


                                         VPI 1           VPI 3      VPI 2           Port 2
        VP Switch

                                                                            VPI 2            VCI 4
                    Port 1

        VCI 1
                         VPI 1                                              VPI 3            VCI 3
        VCI 2



        VCI 1                                                                                VCI 1
                         VPI 4                                              VPI 5
        VCI 2                                                                                VCI 2

                                                                                    Port 3

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NW98_US_811                                                                                          18
           Virtual Channels
           and Virtual Paths
                                 Virtual Channel Connection (VCC)

                                            Virtual Path
                                          Connection (VPC)

               UNI
                                                                             UNI
                                    NNI                 NNI
                         VC                     VP                   VC
                        Switch                 Switch               Switch

                     VPI = 1              VPI = 2            VPI = 26         VPI = 20
                     VCI = 1              VCI = 44           VCI = 44         VCI = 30


   • This hop-by-hop forwarding is known as cell relay


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NW98_US_811                                                                              19
           Rudimentary ATM Concepts


                 • Physical layer
                 • Signaling
                 • Cell format
                 • Connection types


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NW98_US_811                           20
           Creating Cells from Packets
                           Dest.      Source                             Frame
                Packet                                    Data
                          Address     Address                            Check



 Cells          Header      Payload


                                Header       Payload


                          SAR                   Header   Payload
               Segmentation and Reassembly

                                                            Header   Payload
          Segmentation Happens at Source

        Reassembly Happens at Destination



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NW98_US_811                                                                      21
           ATM Cell Header

                           5 Byte
                           Header

               53 Bytes

                          48 Byte
                          Payload




                          ATM Cell
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NW98_US_811                          22
           ATM Cell Header Details
     GFC (4)                                                       VPI (12)
                   VPI (8)
                                                                               VCI (16)
     VCI (16)                  GFC     Generic Flow Control
                                       UNI Cells Only!
                  PTI    CLP                                                  PTI   CLP
                               VPI/VCI Identifies Virtual
                HEC                    Paths and Channels                 HEC

                               PTI     Payload Type Identifier
                                       3 Bits:
               48 Byte                                                  48 Byte
               Payload                      1. User/Control Data        Payload
                                            2. Congestion
                                            3. Last Cell
                               CLP     Cell Loss Priority Bit
        ATM UNI Cell           HEC     Header Error Check           ATM NNI Cell
                                       8 Bit CRC




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NW98_US_811                                                                               23
           Rudimentary ATM Concepts


                 • Physical layer
                 • Signaling
                 • Cell format
                 • Connection types


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NW98_US_811                           24
           ATM Connection Types



                    • PVC
                    • SVC
                    • Soft PVC



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           Connection Types
                        S2   1   S6                           S2       S6

                    1                 1
               S1                         S8          S1       S3      S5    S8

                        S3       S5                            VC
                    2                 2

                        S4   2   S7                           S4       S7

        Connectionless: Packet Routing         Connection Oriented: Cell Switching
        • Path 1 = S1, S2, S6, S8              • VC = S1, S4, S7, S8
        • Path 2 = S1, S4, S7, S8              • Data takes the same path
                                                 and arrives in sequence
        • Data can take different path
          and can arrive out of order

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NW98_US_811                                                                          26
           Permanent Virtual Circuit (PVC)
                               Input           Output                         Input          Output
                              Port VPI/VCI Port VPI/VCI                   Port VPI/VCI Port VPI/VCI
                               1     29     3     45                       1     33     3     02
                               2     52     4     15                       2     15     3     14
                      29
               A               1     64     3     29                       1     64     3     29
                               3     29     1     64                       3     29     1     64
                               1
                                         4          15            2


                               2     3
                                               45                     3
                                                                                                 C
                                                                              14
               B             30                                       3                 43
                                                             16                2
                    Input          Output                                           Input        Output
                                                         2        1
                   Port VPI/VCI Port VPI/VCI                                       Port VPI/VCI Port VPI/VCI
                    1     45     2     16                    10       4             1     16     2     43
                    2     52     1     29                                           3     14     4     10
                    1     64     3     29                                 D         1     64     3     29
                    3     29     1     64                                           3     29     1     64



                    • VPI/VCI tables in network equipment
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                      updated by administrator
NW98_US_811                                                                                                    27
           Switched Virtual Circuit (SVC)
                                Input            Output                   Input            Output
                               Port VPI/VCI Port VPI/VCI              Port VPI/VCI Port VPI/VCI
                                                                       1     29     3     45


               A                1       64       3   29                   1        64     3     29
                                3       29       1   64                   3        29     1     64
                               1
          UNI                                4                1
       Signaling                                                                 UNI
                                                    NNI                       Signaling
                               2        3        Signaling        3
                                                                                                C
               B                                                  3
                                                                              2
                    Input           Output                                         Input        Output
                                                          2   1
                   Port VPI/VCI Port VPI/VCI                                      Port VPI/VCI Port VPI/VCI
                                                                  4

                    2     52        1       29
                    1     64        3       29                        D            1     64     3     29
                    3     29        1       64                                     3     29     1     64



                        • Dynamically set up connections
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                          via signaling
NW98_US_811                                                                                                   28
           Switched Virtual Circuit (SVC)
                                 Input           Output                   Input             Output
                                Port VPI/VCI Port VPI/VCI             Port VPI/VCI Port VPI/VCI
                                 1     29     3     45                 1     29     3     45


               A                 1     64        3   29                   1         64     3     29
                                 3     29        1   64                   3         29     1     64
                                 1
          UNI                               4                 1
       Signaling                                                                     UNI
                                                    NNI                           Signaling
                                 2     3         Signaling        3
                                                                                                 C
               B                                                  3
                                                                              2
                      Input          Output                                         Input        Output
                                                          2   1
                     Port VPI/VCI Port VPI/VCI                                     Port VPI/VCI Port VPI/VCI
                      1     45     2     16                       4                 1     16     2     43
                      2     52     1     29
                      1     64     3     29                           D             1     64     3     29
                      3     29     1     64                                         3     29     1     64



                   • Transfer data over newly established link
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NW98_US_811                                                                                                    29
           Switched Virtual Circuit (SVC)
                                Input            Output                   Input             Output
                               Port VPI/VCI Port VPI/VCI              Port VPI/VCI Port VPI/VCI
                                                                       1     29     3     45


               A                1       64       3   29                   1         64     3     29
                                3       29       1   64                   3         29     1     64
                                1
          UNI                                4                1
       Signaling                                                                     UNI
                                                    NNI                           Signaling
                               2        3        Signaling        3
                                                                                                 C
               B                                                  3
                                                                              2
                    Input           Output                                          Input        Output
                   Port VPI/VCI Port VPI/VCI              2   1                    Port VPI/VCI Port VPI/VCI
                                                                  4
                    2     52        1       29
                    1     64        3       29                        D             1     64     3     29
                    3     29        1       64                                      3     29     1     64



                     • Dynamically tear down connections
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                       via signaling
NW98_US_811                                                                                                    30
           Soft PVC
                                Input            Output              Input             Output
                               Port VPI/VCI Port VPI/VCI         Port VPI/VCI Port VPI/VCI
                                1     29     3     45             1     29     3     45


                                1       64       3   29              1         64     3     29
               A                3       29       1   64              3         29     1     64
                                1
          UNI
       Signaling                                                                UNI
                                                    NNI                      Signaling
                                        3        Signaling                                  C
               B
                                                                         1
                    Input           Output                                     Input        Output
                   Port VPI/VCI Port VPI/VCI                 2                Port VPI/VCI Port VPI/VCI
                                                                               1     16     2     43
                    2     52        1       29
                    1     64        3       29                   D             1     64     3     29
                    3     29        1       64                                 3     29     1     64



                   • PVC established manually across UNI
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                     and dynamically across NNI
NW98_US_811                                                                                               31
           Agenda
               • Introduction
               • ATM Fundamentals
                 Rudimentary ATM Concepts
                 ATM Reference Model
                 ATM Service Categories
                 Traffic Management
               • ATM Transport Standards
               • Campus ATM Internetworking
               • Wrap Up
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NW98_US_811                                   32
           ATM Reference Model


               • Physical layer
               • ATM layer
               • ATM adaptation layer
               • A day in the life of a cell


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NW98_US_811                                    33
           ATM Reference Model

                          ATM
                    Adaptation Layer
                         (AAL)


                       ATM Layer




                     Physical Layer




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NW98_US_811                            34
           ATM Reference Model
                           Physical Layer
            ATM
      Adaptation Layer     Two Sublayers:
           (AAL)
                           • Transmission Convergence (TC)
                              Framing
               ATM Layer      HEC

                           • Physical Media Dependent
                             (PMD)
       Physical Layer
                              Physical media coding




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NW98_US_811                                                  35
           Physical Layer
                        Framing          Data                            Media
                                         Rate
                                         (Mbps)    Multi-   Single-   Coaxial   UTP–5   UTP–3   STP
                                                   Mode      Mode      Cable
          ATM                                      Fiber     Fiber
     Adaptation Layer   DS1              1.544                                                  (TP)
          (AAL)           E1             2.048
                          J2              6.23                                                  (TP)
                        DS3                45
                          E3               34
          ATM Layer       E4              139
                                                                        X

                        ATM25            25.6
                        STS 1            51.8
       Physical Layer   STS3c/STM1       155                                             X
                        STS12c/STM4       622
                        4B/5B (TAXI)      100
                        8B/10B            155
                        (Fiberchannel)




                          = Standardized          X = Proposed/In Progress

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NW98_US_811                                                                                        36
           ATM Reference Model
                             ATM Layer
            ATM
      Adaptation Layer
           (AAL)
                           • Cell header insertion/removal

               ATM Layer
                           • Cell Relay
                           • Multiplexes/demultiplexes cells
                             of different connections
         Physical Layer




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NW98_US_811                                                    37
           ATM Layer
                                                 Virtual Channel
                                                Connection (VCC)
          ATM
     Adaptation Layer                             Virtual Path
          (AAL)                                 Connection (VPC)


          ATM Layer       UNI                                                         UNI

                                              NNI             NNI
                                      VC              VP                  VC
       Physical Layer                Switch          Switch              Switch

                                VPI = 0         VPI = 12           VPI = 26       VPI = 0
                                VCI = 38        VCI = 44           VCI = 44       VCI = 36


                 • Provides VPI/VCI values in header
                 • Ensures that cells stay in the correct order

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NW98_US_811                                                                                  38
           ATM Reference Model
                    ATM Adaptation Layer (AAL)
            ATM
      Adaptation Layer
           (AAL)
                           Two Sublayers:

               ATM Layer
                           • Convergence Sublayer (CS)
                           • Segmentation and
                             Reassembly (SAR)
         Physical Layer




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NW98_US_811                                              39
           ATM Adaptation Layer—AAL
               ATM               PB X           AAL
          Adaptation Layer
               (AAL)
                                                      S
                                                C
                                                      A
                ATM Layer                       S
                                                      R


               Physical Layer




                                AAL = CS + SAR
                                • CS—cell tax
                                • SAR—cell <-> packet
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NW98_US_811                                               40
           AAL Cell Tax
               AAL-1 Cell Tax               AAL-2 Cell Tax

                  5 Byte                      5 Byte
                  Header                      Header         1–48
                                  1 Byte                     Bytes
                  47 Byte                    1–47 Byte
                  Payload                     Payload



               AAL-3/4 Cell Tax             AAL-5 Cell Tax

                   5 Byte                     5 Byte
                   Header                     Header
                                                             no
                  44 Byte                     48 Byte        tax
                                  4 Bytes
                  Payload                     Payload




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NW98_US_811                                                          41
           ATM Reference Model


               • Physical layer
               • ATM layer
               • ATM adaptation layer
               • A day in the life of a cell


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NW98_US_811                                    42
           A Day in the Life of a Cell
                           ATM Payload Processing
               TCP            TCP Packet                           TCP Header      App Data

               IP             IP Datagram             IP Header    TCP Header      App Data

               LLC/SNAP                       LLC     IP Header    TCP Header      App Data

                    Convergence
                    Sublayer (CS)
                                  cell tax    LLC     IP Header    TCP Header      App Data
               AAL                             Put in 48 Byte Cells—SAR into PDU
                        SAR


               ATM            Add 5 Byte Headers with VPI/VCI and CLP
                                     Transmission Convergence (STS, STM, DS)
               PHY
                                       Physical Media (MMF, SMF, STP, UDP,…



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NW98_US_811                                                                                   43
           Agenda
               • Introduction
               • ATM Fundamentals
                  Rudimentary ATM Concepts
                  ATM Reference Model
                  ATM Service Categories
                  Traffic Management

               • ATM Transport Standards
               • Campus ATM Internetworking
               • Wrap Up
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NW98_US_811                                   44
           ATM Service Categories
               • Service Criteria
                 Traffic descriptors
                 QoS parameters

               • Service Categories
                 Constant Bit Rate (CBR)
                 Variable Bit Rate (VBR)
                 Unspecified Bit Rate (UBR)
                 Available Bit Rate (ABR)
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NW98_US_811                                   45
           ATM Service Criteria
                     Contract




                     Contract


                                          ATM Network
                     Contract
               • Traffic Descriptors
                  Peak cell rate
                  Sustainable cell rate
                  Maximum burst size
                  Minimum Cell Rate

               • Quality of Service
                  Delay
                  Cell loss
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NW98_US_811                                             46
           ATM Service Criteria
                          Traffic Descriptors
               • Peak Cell Rate—PCR—Maximum data rate
                 a connection can handle without losing data
               • Sustainable Cell Rate—SCR—Average ATM
                 cell throughput the application is permitted
               • Maximum Burst Size—MBS—Size of the
                 maximum burst of contiguous cells that
                 can be transmitted
               • Minimum Cell Rate—MCR—Rate of an
                 application‘s ability to handle latency
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NW98_US_811                                                     47
           ATM Service Criteria
                     QoS—Delay

    • Maximum Cell Transfer Delay—MCTD
      How long the network can take to transmit
      a cell from one endpoint to another
    • Cell Delay Variation Tolerance—CDVT
      Line distortion caused by change in
      interarrival times between cells aka jitter


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           ATM Service Criteria
                         QoS—Cell Loss


               • Cell Loss Ratio—CLR
                 Acceptable percentage of cells that
                 the network can discard due to
                 congestion



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NW98_US_811                                            49
           ATM Service Categories
               • Service Criteria
                 Traffic parameters
                 QoS parameters

               • Service Categories
                 Constant Bit Rate (CBR)
                 Variable Bit Rate (VBR)
                 Unspecified Bit Rate (UBR)
                 Available Bit Rate (ABR)
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NW98_US_811                                   50
           ATM Service Categories
                               Constant Bit Rate (CBR)
                               Application
                                 Real Time Voice and Video




          Traffic Descriptor                      QoS
                                                               Tolerance

                   PCR                             LOW                     HIGH

               Peak Cell Rate
                                                           Cell Loss
                                                        Cell Delay


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NW98_US_811                                                                       51
           ATM Service Categories
                  Variable Bit Rate (VBR-RT/VBR-NRT)
                               Application
                                 Packetized Voice/Video, SNA




          Traffic Descriptor                      QoS
                      PCR                                       Tolerance
                  Peak Cell Rate
                                                   LOW                        HIGH
                      SCR
               Sustainable Cell Rate
                      MBS
               Maximum Burst Size                             Cell Loss     Cell Delay
                                                        Cell Delay (RT)     (NRT)


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NW98_US_811                                                                              52
           ATM Service Categories
                          Unspecified Bit Rate (UBR)
                               Application
                                         Data Transfer




          Traffic Descriptor                      QoS
                                                         Tolerance

               No Guarantees                       LOW                  HIGH
               Send and Pray
                                                         Cell Delay
                                                                 Cell Loss


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NW98_US_811                                                                    53
           ATM Service Categories
                             Available Bit Rate (ABR)
                                Application
                                   LAN Interconnect for Data




           Traffic Descriptor                     QoS
                                                               Tolerance
                      PCR
                  Peak Cell Rate                   LOW                       HIGH
                     MCR
                Minimum Cell Rate
                                                         Cell Loss   Cell Delay


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                  Also uses Congestion Feedback Mechanisms
NW98_US_811                                                                         54
           Agenda
               • Introduction
               • ATM Fundamentals
                  Rudimentary ATM Concepts
                  ATM Reference Model
                  ATM Service Categories
                  Traffic Management

               • ATM Transport Standards
               • Campus ATM Internetworking
               • Wrap Up
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NW98_US_811                                   55
           Traffic Management

               • Why traffic management?
               • Traffic control techniques
               • ABR congestion feedback




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NW98_US_811                                   56
           Why Traffic Management?



               • Proactively combat congestion
               • Provision for priority control
               • Maintain well-behaved traffic



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NW98_US_811                                       57
           Why Traffic Management?
               Cell Loss—Data‘s Critical Enemy
                          Ethernet (1500 Bytes) = 32 Cells
                             FDDI (4470 Bytes) = 96 Cells
                 IP over ATM–1577 (9180 Bytes) = 192 Cells

                                 TCP/IP Packet

                                                 X


               • Lose one cell and the rest are useless
               • Need to re-transmit 32+ cells for one cell lost
               • Congestion collapse is the result

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NW98_US_811                                                        58
           Traffic Control Techniques



     • Connection management—Acceptance
     • Traffic management—Policing
     • Traffic smoothing—Shaping



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NW98_US_811                             59
           Traffic Control Techniques
               Connection Management
                      Contract



                      Contract


                                           ATM Network
                     Contract
                • Traffic Parameters
                   Peak cell rate
                   Sustainable cell rate
                   Burst tolerance
                   Etc.
                • Quality of Service
                   Delay
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NW98_US_811                                              60
           Traffic Control Techniques
                     Connection Management
                 Connection Admission Control (CAC)
               I want a VC:                          CAC
               X Mbps                         Can I Support this
               Y Delay                         Reliably without
               Z Cell Loss                    Jeopardizing Other
                                                  Contracts?
                   Guaranteed QoS Request


                       No
                        or
                Yes, Agree to a
                Traffic Contract   Contract
                                                 ATM Network

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NW98_US_811                                                        61
           Traffic Control Techniques
                                 Traffic Management
                Usage Parameter Control (UPC) aka Policing

                      Contract                    You are
                                           Not in Conformance
                                            with the Contract.
                                            What Should the
                                              Penalty Be??




                                                                 ?DECISION?
                 REBEL
               APPLICATION                                • PASS
                                              ATM Network • MARK CLP BIT
                                                          • DROP
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NW98_US_811                                                                   62
           Traffic Control Techniques
                    Traffic Management

                             UPC
                                         Marked
                0    0   0           0       1      0


                         D          ?DECISION?
                         r         • PASS
                         o
                         p
                                   • MARK CLP BIT
                                   • DROP

   • CLP Control—When congested, drop marked cells
   • Public UNI—Generic Cell Rate Algorithm (GCRA)

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NW98_US_811                                             63
           Traffic Control Techniques
                         Traffic Management

                                      UPC
                                                Marked
                     0    0   0             0       1    0


                              D
                              r
                                  3    2
                              o
                              p


               • Tail Packet Discard (TPD)
               • Discard cells from same ‗bad‘ packet

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NW98_US_811                                                  64
           Traffic Control Techniques
                         Traffic Management
       Intelligent Tail Packet Discard
                             ATM/Switch
                                    Output Buffer
                UPCEOM 1 0
                             X
                     6       7      3     2     1


                      5

                         4
                                                    Early Packet Discard
                                                                     Output Queue
                                                        EOM   EOM


                                                                    EPD Threshold




               aka UBR+
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NW98_US_811                                                                         65
           Traffic Control Techniques
                   Traffic Management
                  Switch without Packet Discard




               Switch with Intelligent Packet Discard




                 Maximize ―Goodput‖
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NW98_US_811                                             66
           Traffic Control Techniques
                                      Traffic Smoothing
                   I Want to
                Comply With My
               Contract. So, I Will                                   Go Ahead,
                 Smooth/Shape                                        Make My Day
                   My Traffic


                                        Shaper
                       Actual Data
                                                 Shaped Data


               Private ATM Network                             Public ATM Network


                               • Traffic shaper at customer site
                               • Changes traffic characteristics

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                               • Leaky bucket algorithm
NW98_US_811                                                                         67
           Traffic Control Techniques
                   ABR Congestion Feedback

               • RM—Resource Management cells
               • Rate-based feedback mechanisms:
                 EFCI marking
                 Relative rate marking
                 Explicit rate marking
                 VS/VD


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NW98_US_811                                        68
           Traffic Control Techniques
                           ABR Congestion Feedback
                     Forward
                                            EFCI Set          EFCI Set
                                                 X                 X



                                                                         Destination

       Source
                                                       RM X     RM X


                                      Congestion
                                      Experienced          Backward
                                      Slow Down

     • EFCI Marking—Explicit Forward Congestion Indicator
               Congestion flag set on forward cells only
               Destination end-system sends RM cells back to source
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NW98_US_811                                                                            69
           Traffic Control Techniques
                     ABR Congestion Feedback
                Forward

                                            RM




                                                             Destination

       Source
                            RM X


                              Congestion
                                                 Backward
                              Experienced
                              Slow Down

                      • Relative rate marking
                          Switches can set congestion flag
                          in backward RM cells
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NW98_US_811                                                                70
           Traffic Control Techniques
                     ABR Congestion Feedback
                                       Congestion Experienced
                                        Slow Down X Amount
                Forward

                                                RM




                                                                Destination

       Source
                              RM


                               Congestion
                                                     Backward
                               Experienced
                               Slow Down

                     • Explicit rate marking
                          Switches can tell source at exactly
                          what rate to transmit
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NW98_US_811                                                                   71
           Traffic Control Techniques
                       ABR Congestion Feedback
                                    Congestion
                                    Experienced
                 Forward            Slow Down




                                                                    Destination

      Source




                                                  Backward

               • VS/VD—Virtual source/virtual destination
                  Breaks the feedback loop into separate segments
                  Shortens length of feedback loop
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NW98_US_811                                                                       72
           Traffic Control Techniques
                       Buffers Are Your Friend
               • Absorb traffic bursts from simultaneous
                 connections
               • Switches schedule traffic based on priority
                 of traffic according to QoS
               • Switch must reallocate buffers as the traffic
                 mix changes
               • Effective buffering maximizes throughput
                 of usable cells as opposed to raw cells
                 (aka goodput)
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NW98_US_811                                                      73
           Agenda
               • Introduction
               • ATM Fundamentals
                 Rudimentary ATM Concepts
                 ATM Reference Model
                 ATM Service Categories
                 Traffic Management
               • ATM Transport Standards
               • Campus ATM Internetworking
               • Wrap Up
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NW98_US_811                                   74
           ATM Transport Standards
    • The ATM forum
    • ATM UNI
               UNI-3.0, 3.1, 4.0
               ILMI and address management

    • ATM NNI
               Path determination
               IISP
               PNNI
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NW98_US_811                                  75
           The ATM Forum
          • Founded in fall of 1991
          • Founding members: Cisco Systems,
            NET, Nortel, Sprint
          • Now over 700 members
          • Working Groups: Signaling, UNI,
            PNNI, LANE, MPOA
          • http://www.atmforum.com
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           ATM Transport Standards



               • UNI 3.0 and 3.1 not interoperable
                 because they use different data link
                 signaling protocols: Q.SAAL vs.
                 SSCOP



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           ATM Transport Standards
                                     Address Management
                                                   20 Bytes (40 Digits)



                                            Prefix                               ESI
                                      13 Bytes (26 Digits)                6 Bytes (12 Digits)


                     AFI       ICD               DSP                             ESI            SEL


                         IDP
                               IDI                 ICD ATM Format
                                                                                                      1 Byte
                                                                    DSP = Domain Specific Part
               AFI   =   Authority and Format Identifier
                                                                    ESI = End System Identifier
               ICD   =   International Code Designator
                                                                          (MAC Address)
               IDP   =   Initial Domain Part
                                                                    SEL = Selector
               IDI   =   Initial Domain Identifier


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NW98_US_811                                                                                                    78
           ATM Transport Standards
                         Address Management

         • Real life ATM address example:
               47.0091.0000.0000.0000.0000.0000.1111.1111.1111.00
          ------------------ATM Prefix------------------------MAC--------SEL


         • Also referred to as an NSAP address


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NW98_US_811                                                                    79
           ATM Transport Standards
                    Address Management
               ILMI Automatic Address Management




     Here is My MAC Address (ESI)
                                       Here is Your ATM Prefix
     (acdc.3124.efa8)
                                             47.0090……
     What is My ATM Prefix?

           Goal: No manual configuration of end stations

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NW98_US_811                                                      80
           ATM Transport Standards
                    UNI 3.X Connection Types

                                           ―Root‖                    ―Leaves‖




               • Point-to-point               • Point-to-multipoint
                  Uni-directional or                Uni-directional
                  bi-directional traffic            (root-to-leaves) only
                                                    Only Root can add leaves
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NW98_US_811                                                                     81
           ATM Transport Standards
                          UNI 4.0

                •Multicast support
                 Leaf initiated joins

                 Group addressing

                •Better QoS definitions



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           ATM Transport Standards
                    Path Determination

               • What is path determination?
               • Static routing: IISP
                 (aka PNNI Phase0)
               • Dynamic routing: PNNI
                 (aka PNNI Phase1)


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           ATM Transport Standards
                 What Is Path Determination?

                                         Destination



                Source


         • Traditionally router-based:
               RIP
               IGRP
               OSPF
               EIGRP
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NW98_US_811                                            84
           ATM Transport Standards
                  What Is Path Determination?

                                        Destination



                Source


         • Now ATM switch-based:
               IISP
               PNNI



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           ATM Transport Standards
                                                IISP
                                               Port 1                 B

               A                                        UNI 3.1/3.0

                        UNI 3.1/3.0
                         for SVC               Port 2

               Destination Primary Secondary

                   B       Port 1     Port 2


                   • Interim Inter-switch Signaling Protocol (IISP)
                       Static route defined in ATM switches
                       Dynamic call setup via UNI signaling
                       Suitable for small ATM networks

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NW98_US_811                                                               86
           ATM Transport Standards
                              PNNI Phase 1




               Peer Group A       Peer Group B   Peer Group C

                              Routing Protocol
                         +    Signaling Protocol

                                 PNNI
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NW98_US_811                                                     87
           ATM Transport Standards
                     PNNI as Routing Protocol
                                          PG
                                                  PG

                                           PG

                                     PG
                                                       PG




           • Distributes reachability and topology information between switches
           • Dynamic re-routing around failures
           • Routing for reachability based on OSPF
           • Peer groups are analogous to an OSPF area
           • PNNI allows hierarchical organization of network
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NW98_US_811                                                                       88
           ATM Transport Standards
                        PNNI as Signaling Protocol
                                                  B                  Link B.3–B.6 does Not
                                                                     have Sufficient AvCR
                                                                              C
                                            B.2       B.3
                        A                                                      C.2

                        A.2
                                    B.1               Crank-   B.6       C.1         C.3
                              A.3         Re-Route     Back
                  A.1

                                                                                           Destination

       Source                              B.4        B.5


                • PNNI—provides a path that satisfies the request QoS
                • Negotiates metrics such as AvCR, MCTD, MCLR
                • Uses Connection Admission Control (CAC)
                • Uses Crankback for re-routing to alternate path
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NW98_US_811                                                                                              89
           Agenda
               • Introduction
               • ATM Fundamentals
                 Rudimentary ATM Concepts
                 ATM Reference Model
                 ATM Service Categories
                 Traffic Management
               • ATM Transport Standards
               • Campus ATM Internetworking
               • Wrap Up
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NW98_US_811                                   90
           ATM Internetworking


                    • Challenges
                    • LANE 1.0
                    • LANE 2.0
                    • MPOA


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           ATM Internetworking
                           The Challenges
               Existing and New                 New
                 Applications                Applications
                                   API
               Network Address

                MAC Address

                     ???

                ATM Address                 ATM Address

                • MAC address to ATM address resolution
                • No Standard ATM API
                • Broadcast handling
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NW98_US_811                                                 92
           ATM Internetworking
                      Overlay Model
                             ATM Addresses
                     Router or             Router or
                      Switch                Switch


                                  ATM
                Ethernet         Network         Ethernet



                             Direct-Attached
                                 Stations
                           Network Addresses,
                            MAC Addresses
               • Multiple layers of addressing
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NW98_US_811                                                 93
           ATM Internetworking
                              Solutions
               Existing and New      Existing and New
                 Applications          Applications
               Network Address       Network Address

                MAC Address               MAC Address

                 RFC1483, RFC1577, LANE, MPOA
                ATM Address               ATM Address



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NW98_US_811                                             94
           ATM Internetworking
                                         LANE 1.0


                                                        ATM Network



               Today‘s Physical LAN Segment

                                                  Emulated LAN (ELAN) Segment

                    • Hides ATM to upper layers
                    • Makes ATM look like Ethernet/Token Ring
                    • Supported in NICs, LAN switches, ATM routers
                    • Allows ATM hosts connectivity with legacy LANs
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NW98_US_811                                                                     95
           ATM Internetworking
                         LANE Terminology
       LEC—LAN Emulation Client
                                        LECS—LAN Emulation
                                        Configuration Server
                                        for Initialization

                                        LES—LAN Emulation
                                        Server for Address
                                        Resolution

                                        BUS—Broadcast and
                                        Unknown Server for
                                  ATM   Data Flooding




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NW98_US_811                                                    96
           LANE in Operation
   • SVC are required to make this a viable technology
   • Setup of all VCC are automatic
                            LECS   LES   BUS




                          LEC             LEC
               Ethernet



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NW98_US_811                                          97
           LANE—End Goal (Logical View)
     • End goal—communication between LECs
                            LECS     LES          BUS


                                                          LANE Servers
                                                          Provide
                                                          Mechanisms
                                                          that Enable
                                Data Direct VCC           LEC-to-LEC
                                                          Communications

                          LEC

                                                    LEC
               Ethernet




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NW98_US_811                                                                98
           ATM Internetworking
                        LANE 2.0
               • LUNI and LNNI
               • Better efficiency of VC‘s
               • Use of ATM QoS
               • Special multicast servers
               • Server redundancy


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           ATM Internetworking
                MPOA—Multi-Protocol over ATM
                                              • For seamless transport
                                                of layer 3 protocols across
                     MPC                        ATM networks
                                              • Goes beyond LANE by
                                                allowing direct ATM
                           Resultant Direct     connectivity between hosts
                     Cut-Through between
                           Different VLANs
                                                in different subnets
                                              • Architecture consists of edge
                                                devices and route servers
               MPC            MPS




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NW98_US_811                                                                   100
           MPOA Service Basics

                           MPOA Components
                   Route Server            Address Resolution
                                           and Can Initiate the
           MPS                             Forwarding of Info
                                           to MPOA Clients
                   Default Forwarder       Connectionless
                                           Unicast Forwarding
          MPC        Edge Device         Edge Device for
                                         separate forwarding
                                         function
                     Enterprise Server        Also may function as
          MPC                                 MPC




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NW98_US_811                                                          101
           MPOA—Query and Response
                                 MPOA Server
                 MPOA Server                         MPOA Server

   MPOA Query
                                    OSPF,
  and Response
                                  EIGRP, etc.

                     Subnet A                       Subnet B
                                    ATM
               Emulated LAN A      Network         Emulated LAN B


                                                                     Edge
                                Resultant Direct
                                                                    Devices
                                Cut-Through VC




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NW98_US_811                                                                   102
           Agenda
               • Introduction
               • ATM Fundamentals
                 Rudimentary ATM Concepts
                 ATM Reference Model
                 ATM Service Categories
                 Traffic Management
               • ATM Transport Standards
               • Campus ATM Internetworking
               • Wrap Up
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NW98_US_811                                   103
           Wrap Up
                       ATM References

               •   http://www.cisco.com
               •   http://www.atmforum.com
               •   e-mail info@atmforum.com
               •   http://cell-relay.indiana.edu
               •   http://www.atmreport.com
               •   http://www.atm-user.com

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               Wrap Up
               Thank You
               Q&A


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