Introduction to WAN Protocols by peterzhangonline

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									WMS-101
3154_06_2001_X   © 2001, Cisco Systems, Inc. All rights reserved.   1




                             Introduction to WAN
                                   Protocols
                                               Session: WMS-101


WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                        2




                                                                        1
                               Technology Assumptions




            • Basic Understanding of the OSI Reference Model
            • Basic understanding of routing and switching.
            • Basic Understanding of Networking Terms &
              Acronyms




WMS-101
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             Definition of a Wide Area Network



    A WAN is a network that covers a broad geographic
      area and often uses transmission facilities provided
     by common carriers. WAN technologies function at
      the lower three layers of the OSI reference model:
                 • Physical Layer (L1)
                 • Data Link Layer (L2)
                 • Network Layer (L3)


WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                   4




                                                                   2
                                         Layer 2 Encapsulation
        OSI Reference                                                  Layer 2 Frames:
          Module                                                       • Transport for L3 across L1
                                                                       • Error Detection & Possible
       Application                                    Application      Correction
       Presentation                                   Presentation
                                                                       • Establish peering across links
          Session                                       Session
        Transport                                      Transport
                                                                       • Different Characteristics
         Network                           Network     Network
            Link                               Link      Link         L2 Encapsulation

         Physical                          Physical     Physical
         CPE A                     Router / WAN         CPE B
                                     Switch X

     Time Division Multiplexing (TDM)
     HDLC                        PPP
     FR / Frame Switching        ATM / Cell Switching
WMS-101
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                   Why Understanding Protocols
                            Matters?

          • Availability
          • Scalability                                              Data Only
          • Efficiency
          • Security                                               Multiservice
          • Life Cycle
          • Cost
WMS-101
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                                                                                                              3
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                                                                                 terms of individual
     Availability                                                                requirements.
                                                                               • Think of long term
     Scalability                                                                 requirements ( 18mos - 3
                                                                                 years )
     Efficiency
                                                                               • Consider if protocol
     Security
                                                                                 overhead or protocol
                                                                                 delay is of more
     Cost                                                                        importance?
     Life Cycle


WMS-101
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                                                Do You Remember?

       • What are the important characteristics to consider in
         evaluating WAN protocols?
       • What are the 3 HDLC Frame Formats?
       • What are two applications of the Multilink Protocol in
         PPP?
       • What equivalent FRF specs exist in Frame Relay?
       • In Frame Relay, what is the purpose of the FECN and
         BECN bits in the Frame Header?
       • What is one of the primary functions of the ATM
         Adaption Layer?

WMS-101
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                                                                                                                 4
                                                               Agenda

                     • Introduction
                     • Time Division Multiplexing (TDM)
                     • High Level Datalink Control (HDLC)
                     • Point to Point Protocol (PPP)
                     • Frame Relay (FR)
                     • Asynchronous Transfer Mode (ATM)
                     • Summary
WMS-101
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                 Time Division Multiplexing (TDM)
                                                 MUX                                                   MUX   D   D   D
                           D       D       D

                                                               D           D           D           D

                                                           E           E           E           E

                                                       E           E           E           E



                                                           8 bits per timeslot

                                                                                                                         Framing
                      TS1                       TS2    •••               TS3
                                                                       TS22 TS23                   TS24      F            (1 bit)

                                     193 bits per frame (24*8 + 1) — 125 µsec

           • T1 (1.54Mbps) = 24 DSO’s or Channels of 64kbps each
           • Timeslots are always present regardless if data is being sent.
           • Bandwidth is statically allocated to the applications
           • Protocol Independent (HDLC, PPP, etc.)
WMS-101
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                                                                                                                                    5
                                  TDM - Application / ISDN
                                                                                                      To Corporate
                                                                                                        Network

                            64Kbps
                                                                  PSTN / ISDN

                 ISDN BRIs                         Switch                       Switch



                      64Kbps
                                                                                     T1 = 24 DS0’s




                                     • Call Oriented Setup (Q.931)
                                     • Fixed Bandwidth (No More / No Less)
                                     • LAP D Frame Format (similar to HDLC)
WMS-101
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                                                    Making The Grade

                                                                                • Definite Support for
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        Protocol                                                                  Multiservice Applications.
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                                                                                • Predictable Delay
     Availability                                 A              A      A       • Bandwidth likely to be
                                                                                  under-utilized.
     Scalability                                  C              C      C
                                                                                • Secure, L1 End-to-End
     Efficiency                                   D              C      D+
                                                                                • Will be around for a while,
     Security                                     A              A      A         but likely usurped by
                                                                                  converged networks.
     Cost                                         D              D      D
                                                                                • Costs can be prohibitive
     Life Cycle                                   C              C      C         in a tariffed environment.


WMS-101
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                                                                                                                     6
                                               Agenda
                    • Introduction
                    • Time Division Multiplexing (TDM)
                    • High Level Datalink Control (HDLC)
                    • Point to Point Protocol (PPP)
                    • Frame Relay (FR)
                    • Asynchronous Transfer Mode (ATM)
                    • IP-VPNs
                    • Summary
WMS-101
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                                               HDLC


       • HDLC supports 16 or 32 bit Checksums
       • HDLC supports 3 modes; NRM, ARM,
         and ABM
       • HDLC LAP B is the WAN relevant
         application
       • HDLC is sequenced and can perform
         Flow and Error control
WMS-101
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                                                                7
                                           HDLC - Frame Format

                                                          L3 Datagram



                  1             1 or 2           1 or 2                   Variable                   2    1


                 Flag Address                   Control                L3 Datagram (Data)            FCS Flag




                        N(R)                     P         N(S)           0            I-Frames

                                                                                            OR

                        0x0F                    0x00          0x0800                   Cisco Frame



            • 3 Frame Types: Information, Supervisory, & Unnumbered
            • Point-to-Point configuration typically employed
            • Cisco HDLC (proprietary) Point-to-Point Configuration
WMS-101
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                                                HDLC - Application

                                                                                                          Internet




       • Point-to-Point Applications (Leased Line)
       • L2 QoS Doesn’t Matter / Data Throughput Matters
       • No Multiservice L2 Intelligence / L3 Queuing can partially assist
      • Under-utilized links makes Multiservice possible on High Speed
WMS-101
        links (DS3+), but unpredictable.
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                                                                                                                          8
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                                                                               • Data Only = Excellent
     Availability                                 A              -      A      • Currently supported up to
                                                                                 DS3 links, with rate
     Scalability                                  B              -      B        limiting for sub.
     Efficiency                                   A              D     B-      • Light Overhead, ideal for
                                                                                 applications where
     Security                                      -             -      -        maximum throughput
                                                                                 matters.
     Cost                                         A              A      A
     Life Cycle                                   C              F      D

WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                                                 17




                                                                     Agenda

                    • Introduction
                    • Time Division Multiplexing (TDM)
                    • High Level Datalink Control (HDLC)
                    • Point to Point Protocol (PPP)
                    • Frame Relay (FR)
                    • Asynchronous Transfer Mode (ATM)
                    • Summary
WMS-101
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                                                                                                                  9
                                                                 PPP

       • Point-to-Point Protocol. Used in Dial, xDSL, ISDN,
         Serial applications
       • PPP can Multiplex multiple Network Protocols over a
         single link (Protocol Agnostic)
       • Options for IP address assignment and management
       • Link Configuration, Quality, and Error Detection
       • Can negotiate additional options for Authentication,
         Compression, Multilink Support, etc.
       • PPP uses an HDLC Frame for Encapsulation

WMS-101
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                                                PPP - Frame Format

                  1          1                  1     2                     0 - 1500            2        1


                 Flag 0xFF                  0x03    0x0800                 L3 Datagram          FCS Flag




       PPP doesn’t assign                                 Indicates the NLPID of the          CRC Error Checking
    individual station address                                L3 Datagram in the
        therefore using the                                  payload of the frame
        broadcast address                                                       Maximum Transmission
                                                                                 Unit (minus overhead)

                                        Indicates transmission of
                                           user data in an non-                                 Protocol ID’s
                                            sequenced frame                                   Novell     0x8137
                                             (connectionless)                                Appletalk   0x809B
                                                                                             NetBIOS     0x00F0
                                                                                              Banyan     0x00BC
                                                                                              More..     0x0000

WMS-101
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                                                                                                                        10
                                               PPP - Operation
  Se2/0:7 PPP: Phase is ESTABLISHING, Passive Open [0 sess, 0 load]
  Se2/0:7 LCP: State is Listen

  Se2/0:7 LCP: I CONFREQ [Listen] id 230 len 27
  Se2/0:7 LCP: AuthProto CHAP (0x0305C22305)
  Se2/0:7 LCP: MagicNumber 0x4CDA0A5B (0x05064CDA0A5B)
  Se2/0:7 LCP: MRRU 1524 (0x110405F4)
  Se2/0:7 LCP: EndpointDisc 1 1720a (0x1308013137323061)
                                                                        LCP:
  Se2/0:7 LCP: O CONFREQ [Listen] id 76 len 30                          • LCP Listen
  Se2/0:7 LCP: AuthProto CHAP (0x0305C22305)
  Se2/0:7 LCP: MagicNumber 0xCC96D7E6 (0x0506CC96D7E6)                  • Option Negotiation
  Se2/0:7 LCP: MRRU 1524 (0x110405F4)
  Se2/0:7 LCP: EndpointDisc 1 3640_PE1 (0x130B01333634305F504531)       • Link Quality is
  Se2/0:7 LCP: O CONFACK [Listen] id 230 len 27                           determined (Optional)
  Se2/0:7 LCP: AuthProto CHAP (0x0305C22305)
  Se2/0:7 LCP: MagicNumber (0x05064CDA0A5B)                             • Network Layer
  Se2/0:7 LCP: MRRU 1524 (0x110405F4)                                     Configuration Begins
  Se2/0:7 LCP: EndpointDisc 1 1720a (0x1308013137323061)
                                                                          (IPCP, IPXCP, ATCP)
   Se2/0:7 LCP: I CONFACK [ACKsent] id 76 len 30
   Se2/0:7 LCP: AuthProto CHAP (0x0305C22305)                           • Link Establishment
   Se2/0:7 LCP: MagicNumber 0xCC96D7E6 (0x0506CC96D7E6)
   Se2/0:7 LCP: MRRU 1524 (0x110405F4)
                                                                          (LCP Open)
   Se2/0:7 LCP: EndpointDisc 1 3640_PE1 (0x130B01333634305F504531)
   Se2/0:7 LCP: State is Open                                           • LCP Termination
WMS-101
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                       PPP - Authentication (CHAP)
                                                                      CHAP Characteristics:
                                                 3640a                • 3-Way Handshake on
                                                                        link establishment.
             1720a
                                                                      • Authenticator sends a
                                                                        “Challenge”
 Both Peers Challenging (Debug):                                      • Peer responds with a
  Se2/0:7 PPP: Phase is AUTHENTICATING, by both [0 sess, 0 load]        value based on a one-
  Se2/0:7 CHAP: O CHALLENGE id 76 len 29 from "3640a"
                                                                        way hash
  Se2/0:7 CHAP: I CHALLENGE id 69 len 26 from "1720a"
  Se2/0:7 CHAP: Waiting for peer to authenticate first                • Authenticator
  Se2/0:7 CHAP: I RESPONSE id 76 len 26 from "1720a"                    validates against its
  Se2/0:7 PPP: Phase is FORWARDING [0 sess, 0 load]
  Se2/0:7 PPP: Phase is AUTHENTICATING [0 sess, 0 load]                 own calculation.
  Se2/0:7 CHAP: O SUCCESS id 76 len 4
  Se2/0:7 CHAP: Processing saved Challenge, id 69
  Se2/0:7 CHAP: O RESPONSE id 69 len 29 from "3640a"

  Se2/0:7 CHAP: I SUCCESS id 69 len 4

WMS-101
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                                                                                                     11
e:
 e:
Need debug
 Need debug
output, but lab is
 output, but lab is
                                        PPP - NCP Negotiation
tore down until
 tore down until
June 4th.
 June 4th.


                                                 3640a     NCP Characteristics:
                                                           • Responsible for
             1720a
                                                             configuring, enabling
                                                             and disabling the L3
 Both Peers Challenging (Debug):
                                                             protocol.
  Holder                                                   • Uses L2 protocol field
                                                             0x8021 to identify the
  Holder
                                                             payload as IPCP
  Holder                                                   • Address Assignment
                                                             (DHCP)
  Holder                                                   • NetBios Name Servers
  Holder                                                   • Domain Name System

WMS-101
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                                               PPP - Multilink




        • LCP Negotiated Option
        • Member Links Identified through Endpoint Discriminator and /
          or Authenticated name.
        • Bundles Multiple Physical Links into a logical bundle
        • Bandwidth on Demand
        • Multiservice support through fragmentation
WMS-101
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                                                                                           12
                                       PPP - Fragmentation &
                                            Interleaving




        • MP Fragmentation Breaks up Large Data Packets in smaller
          sequenced fragments.
        • Fragment-Delay is used to stipulate the maximum time a
          fragment can be on an individual link
        • MP creates opportunities for non-MP encapsulated traffic (I.e,
          RTP) used in Voice applications to be interleaved.
        • MP fragmentation and interleaving ideal in low speed (<
          1.2Mbps) where delay is priority over throughput.
WMS-101
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                                                                               • Primarily used in Data
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                                                                                 applications, however,
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                                                                                 can be used from
     Availability                                 A             B-      B        Multiservice
     Scalability                                  A             B-      B      • Mature Protocol with new
                                                                                 life in Broadband
     Efficiency                                   A              B     B+        Aggregation applications
     Security                                     B              -      B      • HDLC style header is
                                                                                 efficient for Data, MP is
     Cost                                         -              -      -        efficient for Multiservice |
                                                                                 BW Aggregation.
     Life Cycle                                   A              A       A

WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                                                    26




                                                                                                                     13
                                                Agenda

                    • Introduction
                    • Time Division Multiplexing (TDM)
                    • High Level Datalink Control (HDLC)
                    • Point to Point Protocol (PPP)
                    • Frame Relay (FR)
                    • Asynchronous Transfer Mode (ATM)
                    • Summary
WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                                    27




                                     Frame Relay - Overview
  N * (N-1) / 2 = Full Mesh                                             Chicago



    5 Sites = 10 LL
 10 Sites = 45 LL                              San Francisco                              New York




                                                               Dallas             Miami




          What is the purpose / advantage of a ‘Virtual Circuit’?
WMS-101
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                                                                                                     14
                                                          Frame Relay

                                                                   SP Network




                                     Branch
                                                                                                HQ
                                                                                                     www.corporate.com

           • Packet Switched (Compared to Circuit Switched)
           • Statistical Multiplexing Alleviates Wasted ‘silence’
           • Uses a Virtual Circuit (VC) or Path through the network
           • BW is not Allocated Until Needed
           • Buffering and Congestion Control mechanisms
           • Relies on Upper Layer Protocols (ex. TCP) for error recovery

WMS-101
           • Frame Relay supported up to 45Mbps
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                         Frame Relay - Frame Format
  Bytes           1                             2                  Variable ( 0 ~ 4096)              2   1


                 Flag                  Header                       L3 Datagram (Data)           FCS Flag




   Bits                         6                    1    1    4          1     1     1    1
                                                                              BE
                                                                       FE




                            DLCI                    C/R   EA   DLCI                CN DE   EA
                                                                         C
                                                                          N




   • DLCI - 10 Bit field (1024 Possible connections), Locally Significant
    • C / R - Undefined Field
    • EA - Extended Address ( 1 = End, 0 = More DLCI in 2nd Octet)
    • FECN - Forward Explicit Congestion Notification ( --> Direction)
   • BECN - Backward Explicit Congestion Notification ( <-- Direction)
   • DE - Discard Eligibility: Set by end node allows frames to be
WMS-101 dropped in a congested network or when CIR is being exceeded
3154_06_2001_X    © 2000, Cisco Systems, Inc.                                                                            30




                                                                                                                              15
                                                Frame Relay - LMI
   Which DLCI’s                                                                      DLCI 19, 23, 58 = Active
    are active?                                              DCE Frame
                                                                 Switch
                                                                                     DLCI 21, 29, 5 = Inactive

                                 DTE
                                                                ry
                                                             qui
                                                       _En
                                                   tu s
                                                Sta
                                                          tu s
                                                       Sta



                 • LMI - Local Management Interface                                       Enquiry Types:
                           – VC Discovery (DLCI)                                             • Short
                                                                                             • Long
                           – Multicasting
                                                                                             • Asynchronous
                           – Global Addressing
                 • LMI is used to check the ‘Status’ of PVCs on the network
                 • LMI Uses reserved DLCI ( 0 = ITU, ANSI or 1023 = Cisco)
WMS-101
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                                       Frame Relay - UNI / NNI
                                                                                                            Site B

                  Site A
                                   DLCI 100 DLCI 120                                           UNI
                                          UNI        Frame
                                                                              NNI                        DLCI 60
                                                                Switch
                                                                                      Frame
                                                                          Service     Switch     UNI
                                                                          Provider                        Site C
                                                                           Cloud
                                                                                               DLCI 80



       • The Service Provider’s cloud could be non-FR (I.e. ATM, etc.)
       • Inverse ARP allows Network Layer address discovery (RFC 1293)
       • Static Mapping required without use of iARP (not manageable)
       • DLCI’s are Locally significant. DLCI swapping is job of FR the
         Switch.
       • The SP network will set FECN & BECN bits based on Congestion
       • The SP will set DE bits based on Service Contracts.
WMS-101
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                                                                                                                          16
                                               Frame Relay - FRF.12
                                                                  DTE - DTE
                                                                Fragmentation
                                            PHY I/F                                          PHY I/F
      DLCI 120
                                                                                                                       DLCI 54
       V         V          V           V
                                                                                                        V     V   V       V
      DLCI 100                                         D   V    D   V   D    V   D   V   D                             DLCI 147
      Data                 Data
                                                                                                       Data       Data




        • Fragment Large frames into a sequence of shorter frames
        • Control Delay ‘critical’ for Multiservice applications (Voice, etc.)
        • Fragmentation occurs on a per-VC basis
        • 2 Byte Sequence Header keeps packets ordered (10 bits seq.)
        • Large Frames hog time on wire, create delay problems
WMS-101
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                                               Frame Relay - FRF.16

                                                      PHY I/F                                PHY I/F
                                               MFR                                                     MFR
                                                                    Data 1

    Data 1             Data 2                                                                                 Data 2       Data 1
                                                      PHY I/F                                PHY I/F
                                                                 Data 2




           Bundle                                               Bundle Links


    • FRF16 = Multilink Frame Relay
    • Same encapsulation as FRF12 - UNI / NNI Fragmentation
    • Increase Bandwidth where there are service offering gaps (T1 x N)
    • Eliminate single points of failure with Physical interfaces.
    • Inverse MUX’ing several Physical Interfaces into 1 Logical Interface
WMS-101
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                                                                                                                                       17
                               Frame Relay - Application

                                                                     Chicago


   • Sales / Remote
                                                                           DLCI 33
     Offices                                   San Francisco
                                                                                                     New York
   • Reduces Interfaces
                                                           DLCI 32
   • Simplify                                     Dallas
                                                                                                 DLCI 34

     Configuration                                                               DLCI 3
                                                                                        DLCI 4
                                                                               DLCI 2
                                                                     DLCI 31   DLCI 1
   • Partial Mesh or
     Hub and Spoke                                                                   Head Quarters
     design
   • Reduce LL costs

WMS-101
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                 Frame Relay - Characterization
   Pros
      • Dynamic Allocation of Bandwidth
           • Bandwidth is not wasted. The hungry mouth gets it.
                                                                          with
           • Statistical Multiplexing allows idle VC’s to share bandwidth with active VC’s
      • Can Be Used for Multiservice Applications
                                                                       (Less
           Frame Switches Are Used for Multiservice Applications (DVV) (Less over
           Subscription and Reasonable Speed Links)
      • Technology is still being enhanced (FRF.12, FRF.16, etc.)
      • Bandwidth is expandable (FRF.16)
   Cons
      • Unable to Guarantee Performance (in FIFO Mode)
                                                             in-
           Frame Switches ‘Typically’ Operate in FIFO (First in-First out) Mode, so One
           Application Can Impact the Performance of Others
      • Medium Delay and Variability in Delay
           Each Switch Has to Receive an Entire Frame before Forwarding It to the Next
                                                                    Switches
           Switch; Therefore Transit Delay Increases with Number of Switches in the Path
           The FIFO Mode of Each Switch Causes a Variability at Each Switch
WMS-101
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                                                                                                                18
                               Frame Relay: Report Card




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                                                                               • Fits into a Multiservice
     Availability                                 A              B      B+       Application.
                                                                               • Speeds up to DS3 and
     Scalability                                  B              -      B        MFR scales (NxT1).
     Efficiency                                   A              B      B+     • Light Protocol Overhead
                                                                                 (2 Bytes) and LFI make it
     Security                                    L2              -      B        efficient for Data and
                                                                                 Multiservice.
     Cost                                        B+              -     B+
     Life Cycle                                   B-            B+      B

WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                                                 37




                                                                     Agenda

                    • Introduction
                    • Time Division Multiplexing (TDM)
                    • High Level Datalink Control (HDLC)
                    • Point to Point Protocol (PPP)
                    • Frame Relay (FR)
                    • Asynchronous Transfer Mode (ATM)
                    • Summary
WMS-101
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                                                                                                                  19
                                               ATM - Overview

       • Connection Oriented transport (VC’s pre-established)
         known as ‘Cell Switching’
       • Hybrid of Circuit Switching and Packet Switching
       • Fixed Cell size 5byte Header + 48byte Payload
         reduces latency typical to large data packets
       • ATM Supports Multiple Qualities of Service
       • Virtual Path + Virtual Channel = Virtual Circuit
       • ATM supports Permanent VC’s and Switched VC’s
       • ATM speeds up to OC-48 (2.5Gbps)

WMS-101
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                                   ATM - Functional Layers
                                                           • Segmentation & Reassembly
                                                           • Payload Error Control
                                                           • End-to-End Timing

            OSI RM                             B-ISDN RM
                                                                      • VPI / VCI Switching
          Network                                AAL                  • Cell MUX / DEMUX
           Layer
                                                                      • Flow Control / HEC
         Data Link                                                    • QoS Support
          Layer                                ATM Layer


           Physical                            Physical
            Layer                              Layer 1                • Bitstream Conversion
                                                                      • ATM Cell Boundaries
WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                               40




                                                                                                20
                                                    ATM - Cell Format
                                                                     Transmission Path
                 H              P                  H         P          H           P     H       P        H       P


                                                   Header                Payload


    GFC                 VPI                             VCI                 PT CLP       HEC
     4                    8                                 16              3       1         8



             GFC - Generic Flow Control                                              VPI - Virtual Path Identifier
             VCI - Virtual Channel Identifier                                        PT - Payload Type
             CLP - Cell Loss Priority                                                HEC - Header Error Check

WMS-101
3154_06_2001_X       © 2000, Cisco Systems, Inc.                                                                       41




                                                       ATM - Operation

                                                                                    Segmentation
             IP Datagram                                         LLC


                                                        IP Data          48         48     48
                                                                                                      ATM Adaption Layer

                                                       VPI / VCI Assignment                               VC MUXing

                                    5                            5              5         5           5        5
                                                                                                               ATM Layer

                                                                     Serialization

         5                        5                     5        101100111010110011000100111101100
                                                                                                               PHY Layer
WMS-101
3154_06_2001_X       © 2000, Cisco Systems, Inc.                                                                       42




                                                                                                                            21
                                   ATM - Traffic Definitions



         • CBR - Constant Bit Rate, Connection Oriented w /
           end-to-end timing required, utilizes AAL1 (Leased
           Line Emulation)
         • ABR - Available Bit Rate
         • UBR - Unspecified Bit Rate, connectionless packet
           data, ‘best-effort’ transport. No guarantees to loss,
           delay, or bandwidth available, utilizes AAL5
         • Others, VBR-NRT, VBR-RT, etc.


WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                                               43




                                               ATM - Application

    • Enterprise WAN
                                                                          Voice - AAL1
      Core                                                                    CBR

    • Define Multiple                              San Francisco
                                                                                                     New York
      Traffic Contracts
    • Predictable Delays
      for Multiservice
      Applications                                                 Data - AAL5
                                                                      UBR
    • No under-utilized
      bandwidth (like                                                                Head Quarters

      TDM)
    • Scale VC’s by
      application.
WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                                               44




                                                                                                                22
                                                                 ATM I-LMI
                                                                                                               Site B

                 Site A
                                    IME                        IME                                      IME
                                                                      ATM
                                                  UNI
                                                                     Switch                               End-System
        End-System                                                                        ATM     IME
                                                          Private / Public               Switch
                                                                                                              Site C
                                                              Switch               Private / Public
                                                                                                    IME
                                                                                       Switch


                 Public ATM Switch
                                                                                     Public ATM Switch
                 • Integrated local management interface-ilmi
                 • Use SNMP across UNI and NNI for ILMI MIB
                 • Uses AAL 5 encapsulation
                 • Used for ATM end system address (AESA) formerly
                   NSAP addressing for svc’s
                 • Automatic recognition of UNI or NNI interface protocol
WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                                                            45




                                                    Making The Grade
                                               Da




                                                               M rvii
                                                               M vc
                                                                se


                                                                O
                                                                se
                                                                ull ce
                                                                 u e
                                                  tta




                                                                  ve
                                                                   tii-




        Protocol
                                                      O
                                                      On




                                                                       ra
                                                                       r
                                                        nl




                                                                         lll
                                                           y
                                                           y




                                                                                   • ATM is great for
     Availability                                 B              B            B      multiservice applications,
                                                                                     data-only pays a cell tax
     Scalability                                  A              A            A    • Bandwidth is scalable up
                                                                                     to 2.5Gbps
     Efficiency                                  B-              A            B+
                                                                                   • Delay is predictable and
     Security                                      -             -            -      bandwidth use is efficient,
                                                                                     more applications coming
     Cost                                        C+              D            -
     Life Cycle                                   B              B            B

WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                                                            46




                                                                                                                             23
                                       ATM - Characterization
Pros
 • Dynamic Allocation of Bandwidth
        Available Bandwidth Is Allocated Dynamically to Any Application that Needs It
        One Application Can Use Bandwidth Allocated to the other if that Traffic Is Not Present
 • Guaranteed performance
                                                                      Schemes
        Cell Switches with Efficient Traffic and Bandwidth Management Schemes Can Ensure that
        Each Application Receives Guaranteed Performance (TM, QoS Queuing, CAC, PNNI/UNI Etc.)
 • Low Delay (Controlled and Bounded) and Low Variability in Delay
        Using Fixed Length Cells Ensures that Network Transit Delay and Variability in Delay
        Is Minimized
                     QoS-
        Switches Use QoS-Based Queuing and Scheduling Such as CBR, VBR, ABR
 • Typically Multiservice
                                                                   Ability
        As a Result of Low Delay, Low Variability in Delay and the Ability to Guarantee Performance,
                                                                      Concurrently
        Cell Switches Are Ideally Suited to Support Multiple Services Concurrently

Cons
 • Overhead
                                                                       Delay
         However the Bandwidth Efficiency and Ability to Provide Low Delay and
         Low Variability in Delay in Cell Switching Easily Overcomes the Small
         Incremental Overhead
WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                                                       47




                                                All Together Now

                                                    VPDN


                 Internet



                                                                                                  Boston
          DS-3                                                                   Chicago

                                                                                           384K      256K
                                                                  OC-3
                                                                                                            New York
     San Francisco




                                                                  Dallas
         ATM                                   Ft. Worth                   256K
         Frame-Relay                                       128K               Austin

         HDLC
         PPPoX
WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                                                       48




                                                                                                                        24
                                               Agenda

                    • Introduction
                    • Time Division Multiplexing (TDM)
                    • High Level Datalink Control (HDLC)
                    • Point to Point Protocol (PPP)
                    • Frame Relay (FR)
                    • Asynchronous Transfer Mode (ATM)
                    • Summary
WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.               49




                                               Summary


          “There is no universally correct WAN
          technology to choose. Understanding
            your requirements and predicting
           growth will be essential elements to
             cost-effective, scalable, efficient
                network implementation.”


WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.               50




                                                                25
                                                 WAN - Futures




                                                 • PPPoX
                                                 • xDSL
                                                 • IP-VPNs
                                                 • MPLS-VPNs

WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                      51




                                               Do You Remember?

       • What are the important characteristics to consider in
         evaluating WAN protocols?
       • What are the 3 HDLC Frame Formats?
       • What are two applications of the Multilink Protocol in
         PPP?
       • What equivalent FRF specs exist for Frame Relay?
       • In Frame Relay, what is the purpose of the FECN and
         BECN bits in the Frame Header?
       • What is one of the primary functions of the ATM
         Adaption Layer?

WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                      52




                                                                       26
                                  Follow On Presentations




        • WMS-201                              Deploying WAN Protocols
        • WMS-301                              Troubleshooting WAN Protocols
        • WMS-210                              Deploying Multiservice Networks
        • VVT-213                              Deploying QoS for Voice & Video



WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                     53




                                                  Q&A


WMS-101
3154_06_2001_X   © 2000, Cisco Systems, Inc.                                     54




                                                                                      27
                       Please Complete Your
                          Evaluation Form
                                                                     WMS-101


WMS-101
3154_06_2001_X    © 2000, Cisco Systems, Inc.                                  55




Presentation_ID   © 2001, Cisco Systems, Inc. All rights reserved.             56




                                                                                    28

								
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