VoIP Network Designed

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VoIP Network Designed Powered By Docstoc
					               VoIP
               Networking
               Design

1171_04F8_c1                1
               Tim Danford
               tdanford@cisco.com
               +1.978.244.8911

1171_04F8_c1                        2
               Agenda
                •Intended VoIP Applications
                •VoIP Introduction
                •Packet Networking Challenges
                •Cisco QoS Toolkit
                •Voice Network Design Issues
                •Network Design Examples

1171_04F8_c1                                    3
               VoIP Gateway Applications

               •PSTN gateway service
               •Route replacement/toll bypass
                 Most common application

               •PBX OPX “extension”
               •H.323 interoperability
                 Supports voice-enabled Web applications


1171_04F8_c1                                               4
               Internet Telephony Service Provider
      ISP “A”                     Local
                                                             Settlement Provider
                                                                   (Trusted 3rd Party)
                                  PSTN
                                                                   Authentication, Call
                                                                   Routing, Billing and
                     V                                              Settlement Server
                                               QoS                                 ISP “B”
                                          Interconnect
                                           (or Internet)
           POP (i)
                                ISP “A”                 ISP “B”
                               Backbone                Backbone



                           V      Local                    Local                         V
                POP (ii)          PSTN                     PSTN




1171_04F8_c1                                                                                 5
               Route Replacement
                    PBX                PSTN
                                                        PBX
                          T1,E1         Telco
                                        Switch


                     V


                                                        V

                                       QoS
                                       WAN
                                  (Intranet/Internet)


          Branch Office                                  Main Office


1171_04F8_c1                                                           6
               PBX OPX Transport
                            PSTN
                                         PBX
                             Telco
                             Switch
                                               4 to 12 Analog

                                         V
                                s
                           3600’ with
                          Voice Module
                     V

               Fax




                            QoS
                            WAN
          Branch Office                   Main Office


1171_04F8_c1                                                    7
               H.323 Interoperability
                                          • H.323 VoIP Local Loop Bypass
               Business                   • Integrated Messaging: Email, VMail, FaxMail
                                          • Interoperability with NetMeeting type programs
                                      PSTN
                                PBX                                      PBX

 I-Phone                  V    Router
 H.323 S/W                     + VoIP
                                                         QoS
                                                         WAN
                                 Local             POP
 I-Phone                         PSTN
 H.323 S/W
               Residential
                                                           Internet       V


                                         xDSL   DSLAM
                              xDSL
 I-Phone                     Modem
 H.323 S/W

                              2nd Line

               Residential
                               Phone                                      Main Office
1171_04F8_c1                                                                              8
               Agenda
                •Intended VoIP Applications
                • VoIP Introduction
                •Packet Networking Challenges
                •Cisco QoS Toolkit
                •Voice Network Design Issues
                •Network Design Examples

1171_04F8_c1                                    9
               Network Convergence
               Applications

                                                        Service

        L3                       IP                    Adaptation
                                                                             IP

                                                           PPP
                Campus




                                      WAN




      L2                 802.N               Frame           ATM
                                             Relay
                                                                         Sonet
       L1                                   F-T1     DS1         DS3   OC3 - OCn



1171_04F8_c1                                                                       10
               L3/L2 Transport Characteristics


           • L3— VoIP                         • L2— VoFR, VoATM
                 Flexible— IP is ubiquitous     “Hard” Qos
                 “Soft” form of QoS             Infrastructure can be rigid
                 IP/UDP/RTP overhead            Standards-based
                 (RTP compression)
                                                Better suited for high
                 Quickly emerging               volume bulk voice
                 technology
                 Standards-based H.323




1171_04F8_c1                                                              11
               Voice over IP Protocols
           Presentation       G.729(A)/G.723(.1)/G.711

           Session             H.323/H.323Gateway

           Transport              RTP/UDP/RSVP

           Network                IP/WFQ/IP-prec

           Link               MLPPP/FR/ATM AAL1

           Physical                    –––



1171_04F8_c1                                             12
               VoIP— Uses Voice Component of H.323

                  System          Video           Audio          User Data
                Control and        I/O             I/O          Applications
               User Interface   Equipment       Equipment          T.120

           System Control
                                               Audio Codec
                   H.245
                  Control       Video Codec    G.711, G.722,          Session Layer
                                H.261, H263   G.723, G.723.1,          and Above
                Call Control                   G.728, G.729
                  H.225.0
               RAS Control
                                              Receive Path
                 H.225.0
                                                 Delay

                                      H.225.0 Layer

                                        LAN Stack
1171_04F8_c1                                                                   13
               H.323 Infrastructure
                      H.323 Terminal                             Gatekeeper



      Corp LAN

                  Router                                                 Gateway
                              Proxy

                                                                                H.320
                                                                                (Over ISDN)

       Intranet                        Real-Time            Telephone          H.324
                                        Network              Network           (Over POTs)



                                            Typical H.323 Applications
                                                                              Speech Only
                                           Internet Phone/I-Fax (VOIP)        (PSTN)
                                   H.323   Data Conferencing (T.120)
                                              Video Conferencing

1171_04F8_c1                                                                                14
               H.323 Signaling
                            Admission Request
                                                        RAS
                            Admission Confirm
                V                                                 Gatekeeper
            H.323
                                  Setup
           Gateway                                      H.225
                                 Connect
                                                        (Q.931)       V
                                                                   H.323
                           Capabilities Exchange                  Gateway
                           Open Logical Channel
                                                        H.245
                     Open Logical Channel Acknowledge

                                  Path

                                  Resv                  RSVP

                               RTP Stream
                               RTP Stream               Media
                               RTCP Stream


1171_04F8_c1                                                                   15
               PBX to Router VoIP Signaling
                                                  H.323 Gateway
               5278305
                                       2
                                  H.225 (Q.931)             5278305


                                  Corporate                       Switch
                                   Intranet
                                                      V


                         1                                   3
               Analog Signaling                   Digital Trunk Signaling
                    FXO/FXS                               CAS:
                                                          E&M
                                                          CCS:
                                                          Q.931/PRI




1171_04F8_c1                                                               16
               RTP/RTCP— RFCs 1889/1890
           • End-to-end network transport function
                Payload type identification
                Sequence numbering
                Timestamping
                Delivery monitoring

           • RTCP (Real-Time Control Protocol) provides
             feedback on the quality of the distribution
           • RTP does not address: Resource reservation
             or guaranteed quality of service


1171_04F8_c1                                               17
               Bandwidth Requirements
                       Voice Band Traffic
                   Encoding/           Result
                   Compression         Bit Rate
                   G.711 PCM         64 kbps (DS0)
                   A-Law/u
                   A-Law/u-Law

                   G.726 ADPCM      16, 24, 32, 40 kbps

                   G.727 E-ADPCM    16, 24, 32, 40 kbps

                   G.729 CS-ACELP        8 kbps

                   G.728 LD-CELP        16 kbps

                   G.723.1 CELP       6.3/5.3 kbps
                                        Variable

1171_04F8_c1                                              18
               G.729 CS-ACELP


         •80 sample frames (10ms) of 16-bit
          linear PCM data into 10 8-bit
          codewords
         •15ms (10ms frame + 5ms look ahead)
         •8kb/s data rate



1171_04F8_c1                                   19
               Agenda
                •Intended VoIP Applications
                •VoIP Introduction
                • Packet Networking Challenges
                •Cisco QoS Toolkit
                •Voice Network Design Issues
                •Network Design Examples

1171_04F8_c1                                     20
               Mean Opinion Score
                                   Channel
                    Source        Simulation       Impairment
                                                     Codec               1   2   3   4   5
                                                      ‘X’

                  “Nowadays, a chicken leg is a rare dish.”

        Rating Speech Quality Level of Distortion
        5        Excellent         Imperceptible
                                                                         1   2   3   4   5
        4        Good              Just perceptible, not annoying
        3        Fair              Perceptible, slightly annoying
        2        Poor              Annoying but not objectionable
        1        Unsatisfactory    Very annoying, objectionable


                                             MOS of 4.0 = Toll Quality


1171_04F8_c1                                                                                 21
               Voice Transport Requirements
     • Subjective quality (MOS)                 • Background noise
               MOS
                                                • Silence suppression
     • Delay and delay variation                    Comfort noise

     • Echo cancellation                        • Language sensitivity

                         VoIP Challenges in the WAN
                                         Loss
                                      Bandwidth
                                        Delay
                                Delay Variation (Jitter)
                     (Amplified with Coexistence of Voice and Data)


1171_04F8_c1                                                             22
               VoIP (G.729) Is Tolerant of
               “Occasional” Packet Loss




                                                missing packet
                           G.729 vocoder algorithm

                • The friendly “retransmission” is of no use in the
                  Voice world… late is as good as never
                • Complex “concealment strategy” in algorithm
                  interpolates lost packets based on context

1171_04F8_c1                                                          23
               Consecutive Packet Losses Degrade
               Voice Quality (Mean Opinion Scores)

                Consecutive
                Frames Lost:         1         2        3           4    5



                M.O.S. :            4.2       3.2      2.4      2.1     1.7




    “G.729 Error Recovery for Internet Telephony”,
    Jonathan Rosenberg, Lucent Technology and Columbia University
    V.O.N. Conference 9/97

1171_04F8_c1                                                                  24
               Echo Is Always Present
               •Echo as a problem is a function of
                the echo delay, and the magnitude
                of the echo

                         (dB)
                                Echo Is Unnoticeable

               Echo Path Loss


                                                Echo Is a Problem


                                      Echo Path Delay (ms)

1171_04F8_c1                                                        25
               How Does Echo Happen?
                  •Echo is due to a reflection
                                         Central Office
                                                          Receive
                                                          Direction
                     2 Wire Local Loop
                                            2w-4w
                         Rx & Tx            Hybrid
                      Superimposed
                                                          Transmit
                                                          Direction
      Impedance mismatch at the 2w-4w hybrid
      is the most common reason for echo




1171_04F8_c1                                                          26
               Delay Budgeting—
               Networked End Points
                    • CODEC
                    • Packetization
                    • Output queuing

                    • Access (up) link transmission
                    • Backbone network transmission
                    • Access (down) link transmission

                    • Input queuing
                    • Jitter buffer
                    • CODEC

1171_04F8_c1                                            26
               Delay— How Much Is Too Much?
               Cumulative Transmission Path Delay

                                                                 CB Zone
                                    Satellite Quality
        High Quality                                             Fax Relay, Broadcast


  0             100     200          300         400       500        600       700     800
                                             Time (msec)
                              Delay Target



                   s
                ITU’ G.114 Recommendation = 0 – 150msec 1-way delay



1171_04F8_c1                                                                              28
               Fixed Delay Components
           Propagation Delay
           Serialization Delay—
           Buffer to Serial Link
           Processing Delay




         • Propagation— six microseconds per kilometer
         • Serialization
         • Processing
                Coding/compression/decompression/decoding
                Packetization
1171_04F8_c1                                                29
               Fixed Frame Serialization Delay Matrix
                                             Frame Size
                             1        64      128     256     512    1024    1500
                            Byte     Bytes   Bytes   Bytes   Bytes   Bytes   Bytes

                  56kbps    143us    9ms     18ms    36ms    72ms 144ms 214ms

                  64kbps    125us    8ms     16ms    32ms    64ms 128ms 187ms
     Link
    Speed         128kbps   62.5us   4ms     8ms     16ms    32ms    64ms    93ms

                  256kbps   31us     2ms     4ms      8ms    16ms    32ms    46ms

                  512kbps   15.5us   1ms     2ms      4ms    8ms     16ms    23ms

                  768kbps   10us     640us 1.28ms 2.56ms 5.12ms 10.24ms 15mss

                  1536kbs    5us     320us 640us     1.28ms 2.56ms 5.12ms 7.5ms




1171_04F8_c1                                                                         30
               Variable Delay Components
                   Queuing   Queuing   Queuing
                    Delay     Delay     Delay




                                                 Dejitter
                                                 Buffer


                      • Queuing delay
                      • Dejitter buffers
                      • Variable packet sizes
1171_04F8_c1                                                31
               Delay Variation— “Jitter”
                                                      Receiver
                         Sender
                                            Network



                A            B              C             Sender Transmits

                                                                   t

                         A              B             C   Sink Receives

                    D1       D2 = D 1       D3 = D2                t


1171_04F8_c1                                                                 32
33
               Calculate Delay Budget
                   Coder Queuing
        Los        Delay Delay                                   Dejitter Buffer
      Angeles      25 ms 6 ms                                        50 ms            Munich
                                            Propagation
                                           Delay— 32 ms

                                       (Private Line Network)
                    Serialization Delay
                            3 ms
                                                                 Fixed     Variable
                                                                 Delay      Delay
                 Coder Delay G.729 (5 msec look ahead)            5 msec
                 Coder Delay G.729 (10 msec per frame)           20 msec
                 Packetization Delay— Included in Coder Delay
                 Queuing Delay 64 kbps Trunk                               6 msec
                 Serialization Delay 64 kbps Trunk                3 msec
                  Propagation Delay (Private Lines)              32 msec
                  Network Delay (e.g.,Public Frame Relay Svc)
                  Dejitter Buffer                                50 msec
                  Total                                         110 msec
1171_04F8_c1                                                                                   34
               Typical Enterprise Network Infrastructure
                                            Distribution Layer

                  Frame Relay                                      Frame Relay
                ATM, SMDS, VSAT                                  ATM, SMDS, VSAT
                     Pt-to-Pt                                         Pt-to-Pt


        Access Layer                          Core Layer
    (Lower Bandwidth and                  (Higher Bandwidth
        Higher Delay)                      and Lower Delay)       Access Layer/Small-Mid
                                                                    Tier Size Network


                      Frame Relay                                  Frame Relay
                    ATM, SMDS, VSAT                              ATM, SMDS, VSAT
                         Pt-to-Pt                                     Pt-to-Pt



                                Access Layer:
                            Area of Most Challenge
                             for VoIP Networking
                             Loss (Bandwidth/Congestion)
                            Delay (Serialization/Propagation)
                              Jitter (Varying Packet Sizes)
1171_04F8_c1                                                                               35
               Access Layer Issues
                               Loss, Delay and Jitter
   Note: These issues exist in the
         Core layer but are dampened                          WAN Transport QoS
         with higher bandwidth                                         Unless Pt-to-Pt:
                                                            Dropped Packets— CIR Rates, ATM QoS
                                                              Delay— NBMA Delays, VSAT Delays
                PBX                                    Jitter— Shared Transport with Other Customers


                                                                                Equally as Important
                                             Frame Relay                       in the Design Process!
                                             ATM, SMDS,                        But Not Discussed Here
                                             VSAT Pt-to-Pt
                                                                                        Small PBX,
                                                                                          Keyset
                                                                                         or POTS
                  Router Egress
     Dropped Packets— Serial Interface Congestion
Serialization Delay— Voice Packet Behind “Jumbogram”
  Varying Packet Sizes— Coexistence of Voice + Data


      s
 Cisco’ QoS Toolkit can help here!

1171_04F8_c1                                                                                         36
               Agenda
                •Intended VoIP Applications
                •VoIP Introduction
                •Packet Networking Challenges
                • Cisco QoS Toolkit
                •Voice Network Design Issues
                •Network Design Examples

1171_04F8_c1                                    37
               QoS Networking Tools

               •Congestion Management (WFQ)
               •QoS Signaling (IP Prec / RSVP)
               •Congestion Avoidance (WRED)
               •Packet Residency (MLPPP)
               •Bandwidth (Header Compression,
                Silence Suppression, VAD)

1171_04F8_c1                                     38
               Weighted Fair Queuing (WFQ)
                                                                                            Two 100 Byte
                                                                                              Packets
                                                    Configurable Queues                    Transmitted for
                                                                                         Every One 200 Byte
                                                                                               Packet
        Two 100 Byte
        Voice Packets                                         1       1                   Therefore = “Fair”


                                                                  2                           2     1    1
      1        2      1                                                       De-
                                                                             queue


                                         Classify
        One 200 Byte
           Data                                                                              Transmit
          Packet                                                                             Scheduling
                                                      Interface Buffer
                                                         Resources


                     Flow Classification/Sorting                            Weighted Fair Scheduling
                •Source and destination address                       •Requested Qos (IP Precedence, RSVP)
                •Protocol                                             •Frame Relay FECN, BECN, DE
                •Session identifier (Port/Socket)                     •Flow throughput (Weighted-Fair)


1171_04F8_c1                                                                                              39
               Configuring WFQ
               (On by Default on Links 2 Meg or Less)
           The following example requests a fair
           queue with 256 dynamic queues,
           1000 RSVP queues, and a congestive
           discard threshold of 64 messages:

                                                interface Serial0/0
                                                 ip address 10.1.0.1 255.255.0.0
                                                 bandwidth 64
                                                 fair-queue 64 256 1000

           !
           midge(config-if)#fair-queue ?
             <1-4096> Congestive Discard Threshold
             <16-4096> Number Dynamic Conversation Queues
             <0-1000> Number Reservable Conversation Queues
             <cr>
1171_04F8_c1                                                                       40
               Displaying WFQ
       Emphasizing the “Fair” in Weighted Fair Queuing
   bottom#sho queu se 0
    Input queue: 0/75/0 (size/max/drops); Total output drops: 0
    Queuing strategy: weighted fair
    Output queue: 31/64/0 (size/threshold/drops)
      Conversations 2/4 (active/max active)
      Reserved Conversations 0/0 (allocated/max allocated)

            weight/discards/interleaves) 24/4096
     (depth/weight                           4096/0/0
                                                                        High BW Flow
     Conversation 184, linktype: ip, length: 1504
     source: 10.1.2.2, destination: 171.68.56.138, id: 0x04CF, ttl: 31,      vs
     TOS: 0 prot: 6, source port 1503, destination port 1034
                                                                      Telnet, VoIP Etc.
            weight/discards/interleaves) 7/4096
     (depth/weight                          4096/0/0
     Conversation 227, linktype: ip, length: 68
     source: 10.1.2.2, destination: 171.68.56.138, id: 0xFCCF, ttl: 31,
     TOS: 0 prot: 17, source port 49608, destination port 49608

1171_04F8_c1                                                                           41
               IP Precedence

           • Set IP Precedence higher on VoIP
                Result = Isolated WFQ queue from Best Effort traffic
                Set at: Endpoint, proxy, or statically through router

           • May scale better than RSVP in
             SOME networks
                 Bulk QoS by customer or network

           • Warning: No admission control


1171_04F8_c1                                                            42
               Setting IP Precedence
  !
  interface Serial0/0
   ip address 10.1.0.1 255.255.0.0
  ip policy route-map testprec
                                                                Option 1
  !
  !
  access-list 101 permit udp any any range 16384 16400
  route-map testprec permit 10
   match ip address 101
   set ip precedence network

                                midge(config-route-map)#set ip precedence ?
                                 <0-7>          Precedence value
                                 critical       Set critical precedence (5)
                                 flash          Set flash precedence (3)
                                 flash-override Set flash override precedence (4)
                                 immediate      Set immediate precedence (2)
                                 internet       Set internetwork control precedence (6)
                                 network        Set network control precedence (7)
                                 priority       Set priority precedence (1)
                                 routine        Set routine precedence (0)

1171_04F8_c1                                                                              43
               Setting IP Precedence
                                                     Option 2
      !
      dial-peer voice 25 voip
       destination-pattern 5011
       req-qos guaranteed-delay
       ip precedence 5
       session target ipv4:10.5.0.1
      !
                                      midge(config)#dial-peer voice 25 voip
                                      midge(config-dial-peer)#ip precedence ?
                                       <0-7> Packet IP precedence value




1171_04F8_c1                                                                    44
               Displaying Effects of IP Precedence
   This Is Using the “Weight” in Weighted Fair Queuing
               bottom#sho queu se 0
                Input queue: 0/75/0 (size/max/drops); Total output drops: 0
                Queuing strategy: weighted fair
                Output queue: 5/64/0 (size/threshold/drops)
                  Conversations 2/7 (active/max active)
                  Reserved Conversations 0/0 (allocated/max allocated)

                       weight/discards/interleaves) 1/585
                (depth/weight                           585/0/0
                Conversation 90, linktype: ip, length: 46
                source: 10.1.1.1, destination: 10.1.1.2, id: 0x0064, ttl: 255,
                TOS: 192 prot: 6, source port 23, destination port 11000

                (depth/weight/discards/interleaves) 3/4096/0/0
                Conversation 219, linktype: ip, length: 68
                source: 10.1.2.2, destination: 171.68.56.138, id: 0x1C7E, ttl: 31,
                TOS: 0 prot: 17, source port 49604, destination port 49604

1171_04F8_c1                                                                         45
               RSVP: Resource Reservation
               Protocol
                                                     Admit
                                                      One




           • IETF signaling protocol
                Reservation of bandwidth and delay

           • Dynamic end-to-end “access lists”
                Programs queuing policy

           • Flow can be signaled by end station or
             by router (static reservation)


1171_04F8_c1                                                 46
               Resource reSerVation Protocol
                                                     EP2
                                                           FLOW
                                                           (RFC 1190)



    EP1                                              EP3



                                                     EP4


                                                     EP5
                    Application Z
                  Sender_Descriptor                    If I Accept I
                                      Path Message   Need to Reserve
                   Sender_Template
                                                       Flowspec X
                   Sender Tspec                        Filterspec Y
                                                             for
                                                      Application Z

1171_04F8_c1                                                       46
               Resource reSerVation Protocol
                                        EP2



    EP1                                 EP3



                                        EP4


                                        EP5
          RESV Message
                                          Send RESV
                                        Set Flowspec X
                                        Set Filterspec Y
                                               for
                                         Application Z

1171_04F8_c1                                          46
               RSVP— QoS Services
                           Guaranteed Service
               Mathematically Provable Bounds on Datagram
                     Queuing Delay and Bandwidth


                     Only if Bit Rate Is Not Exceeded!

                        Controlled Load Service
                    No Loss for a Specified Bit Rate
                 Models Service in an Unloaded Network


1171_04F8_c1                                                49
               Resource Reservation
               Protocol (RSVP)
                    Works in Conjunction with Weighted Fair Queuing
                                                    Configurable Queues                   Reserved Queue
         Reserved
                                                                                          for Flow, Lower
          Packet
                                                                                          Weight applied
                                                                  1                       to Queue


                                                              2
                                                                                              2           1
         1      2                                                             De-
                                                                             queue


   Small       Large                  Classify
Volume/Size Volume/Size
  Packet      Packet
                                                                                             Transmit
                                                      Interface Buffer                       Scheduling
                                                         Resources

                      Flow Classification                                    Reserved Flow Scheduling
                •Source and destination address                          •Works in conjunction with WFQ
                •Protocol                                                •Reserved queue for RSVP flow
                •Session identifier (Port/Socket)                        •Queues serviced by “Weight”

1171_04F8_c1                                                                                                  50
               Configuring RSVP
               ip rsvp bandwidth [interface-kbps] [single-flow-kbps]


                         !
                         interface Serial0/0
                          ip address 10.1.0.1 255.255.0.0
                          ip rsvp bandwidth 56 30
                          ip policy route-map testprec
                          bandwidth 64
                          fair-queue 64 256 1000
                         !




1171_04F8_c1                                                           51
               Verifying Reservation Accepted

bottom#sho ip rsvp installed
BPS      To           From     Protoc DPort Sport Weight Conversation
18K 171.68.56.138 10.1.2.2     UDP 49608 49608      4       264



bottom#sho ip rsvp reservation
     To        From    Proto DPort Sport Next Hop    I/F Fi Serv BPS Byts
171.68.56.138 10.1.2.2 UDP 49608 49608 10.1.1 .2    Se0 FF RATE 18K 3K




1171_04F8_c1                                                            52
               Monitoring Queue Operation
         bottom#sho que se 0
          Input queue: 0/75/0 (size/max/drops); Total output drops: 0
          Queueing strategy: weighted fair
          Output queue: 44/64/0 (size/threshold/drops)
            Conversations 3/5 (active/max active)
            Reserved Conversations 1/1 (allocated/max allocated)

           (depth/weight/discards/interleaves) 21/4096/0/0
           Conversation 195, linktype: ip, length: 1504
           source: 10.1.2.2, destination: 171.68.56.138, id: 0xD5E8, ttl: 31,
           TOS: 0 prot: 6, source port 1503, destination port 1045


                  weight/discards/interleaves) 22/4/0/0
           (depth/weight                           4
           Conversation 264, linktype: ip, length: 68
           source: 10.1.2.2, destination: 171.68.56.138, id: 0xAFE9, ttl: 31,
           TOS: 0 prot: 17, source port 49608, destination port 49608


1171_04F8_c1                                                                    53
               Weighted Random Early
               Detection (W-RED)


           •Congestion avoidance
           •Transport protocol responds to loss
           •Global synchronization




1171_04F8_c1                                      54
               Configuring WRED
      random-detect [weighting]
      Syntax Description

       weighting
                                (Optional) Exponential weighting constant in the range 1 to
                                16 used to determine the rate that packets are dropped
                                when congestion occurs.
                                The default is 10 (that is, drop 1packet every 210).



                       !
                       interface Serial0/0
                        ip address 10.1.0.1 255.255.0.0
                        ip rsvp bandwidth 56 30
                        bandwidth 64
                        random-detect 9




1171_04F8_c1                                                                                  55
               Multilink PPP with
               Fragmentation and Interleave
                                                 64 kbps Line



               Real-Time MTU               Elastic Traffic MTU
                                       214ms Serialization Delay
                                    for 1500 byte Frame at 64 kbps



                                                 64 kbps Line

                                   Addendum to PPP Specification
                     Elastic MTU   Elastic MTU   Real-Time MTU       Elastic MTU




1171_04F8_c1                                                                       56
               Multilink PPP Fragmentation and Interleave
               with RTP Header Compression (CRTP)
                                                                                             VoIP Frame
                                                                                             Interleaved,
                                                  Configurable Queues
                                                                                            Compressed
     RTP Traffic                                                                          and Given Priority
   Voice/Video Etc.                                                                         via WFQ, IP
                                                                  1                         Prec or RSVP

                           RTP-HC
                                                          2   2   2
                                                                                          2   2   1   2
         1       2                                                           De-
                                                                            queue
                           Non-RTP
   Small       Large                   Classify
Volume/Size Volume/Size
  Packet      Packet
                                                                                              Transmit
                                                      Interface Buffer                        Scheduling
                                                         Resources

                        Flow Classification
                                                                      Weighted Fair or Reserved Scheduling
                  •Source and Destination Address
                  •Protocol
                  •Session Identifier (Port/Socket)


1171_04F8_c1                                                                                              57
               PPP Fragmentation Frame
               Size Formula
                        Calculating Fragment Size
               “Real Time Packet Interval / Time per byte for BW = Fragment Size”


                                           Example

                                   20ms / 143us = 140bytes




      1 VoIP Frame Every           Time to Send 1byte      Max Byte Size to Allow
     20ms 78 byte Packets           on 64kbps Circuit    Interleaving of “Real Time”
                                                             Packets Every 20ms



1171_04F8_c1                                                                           58
               PPP Fragmentation Frame
               Size Matrix
                                     Real Time Packet Interval

                             10ms    20ms     30ms    40ms    50ms    100ms 200ms

                              70       140     210     280     350     700    1400
                  56kbps     Bytes    Bytes   Bytes   Bytes   Bytes   Bytes   Bytes
                              80       160     240     320     400     800    1600
                  64kbps     Bytes    Bytes   Bytes   Bytes   Bytes   Bytes     X
                                                                              Bytes
    Link                      160      320     480     640     800    1600    3200
   Speed          128kbps    Bytes    Bytes   Bytes   Bytes   Bytes     X
                                                                      Bytes     X
                                                                              Bytes
                              320      640     960    1280    1600    3200    6400
                  256kbps    Bytes    Bytes   Bytes   Bytes     X
                                                              Bytes     X
                                                                      Bytes     X
                                                                              Bytes
                              640     1280    1920    2560    3200    6400    12800
                  512kbps    Bytes    Bytes     X
                                              Bytes    X
                                                      Bytes     X
                                                              Bytes     X
                                                                      Bytes     X
                                                                              Bytes
                             1000     2000    3000    4000    5000    10000   20000
                  768kbps    Bytes      X
                                      Bytes     X
                                              Bytes    X
                                                      Bytes     X
                                                              Bytes     X
                                                                      Bytes     X
                                                                              Bytes
                             2000     4000    6000    8000    10000   20000   40000
                  1536kbs     X
                             Bytes      X       X      X
                                                      Bytes     X       X      X
                                                                              Bytes
                                      Bytes   Bytes           Bytes   Bytes


                X — Fragmentation not an issue due to BW + Interval Combination

1171_04F8_c1                                                                          59
               Configuring Multilink PPP
               Fragmentation and Interleave
                 Bottom                                          Top


    interface Virtual-Template1                    interface Virtual-Template1
     ip unnumbered Loopback0                        ip unnumbered Loopback0
     ip rtp reserve 49580 100 18                    ip rtp reserve 49600 100 18
     no ip mroute-cache                             no ip mroute-cache
     bandwidth 64                                   bandwidth 64
     fair-queue 64 256 1000    Port l Range I kbps fair-queue 64 256 1000
     ppp multilink                                  ppp multilink
     ppp multilink fragment-delay 140               ppp multilink fragment-delay 140
     ppp multilink interleave                       ppp multilink interleave
    !                                              !
    interface Serial0                              interface Serial0
     no ip address                                  no ip address
     encapsulation ppp                              encapsulation ppp
     bandwidth 64                                   bandwidth 64
     no fair-queue                                  no fair-queue
     ppp multilink                                  clockrate 64000
                                                    ppp multilink
1171_04F8_c1                                                                      60
               Verifying Fragmentation
               bottom#sho ppp multilink

               Bundle top, 1 member, Master link is Virtual-Access1
                0 lost fragments, 0 reordered, 0 unassigned, sequence 0xA0/0x35AA rcvd/sent
                0 discarded, 0 lost received, 86/255 load

               Member Link: 1 (max not set, min not set)
               Serial0 140 weight, 2 max fragments

               bottom#deb ppp mult
               Multilink activity debugging is on
               bottom#
               *Mar 1 01:43:07: Se0 MLP: O seq C00059E5 size 38
               *Mar 1 01:43:07: Se0 MLP: O seq C00059E6 size 38
               *Mar 1 01:43:07: Se0 MLP: O seq 800059E7 size 140
               *Mar 1 01:43:07: Se0 MLP: O seq 59E8 size 140
               *Mar 1 01:43:07: MLP: Packet being interleaved from queue 1157428
               *Mar 1 01:43:07: MLP: Packet being interleaved from queue 1157428
               *Mar 1 01:43:07: Se0 MLP: O seq 59E9 size 140
               *Mar 1 01:43:07: MLP: Packet being interleaved from queue 1157428
               *Mar 1 01:43:07: Se0 MLP: O seq 59EA size 140

1171_04F8_c1                                                                                  61
               Monitoring Queue Operation
                bottom#sho queue virtual-access 1
                 Input queue: 0/75/0 (size/max/drops); Total output drops: 0
                 Queuing strategy: weighted fair
                 Output queue: 23/64/0/2534 (size/threshold/drops/interleaves)
                   Conversations 2/3 (active/max active)
                   Reserved Conversations 0/0 (allocated/max allocated)

                                         interleaves)            2534
                 (depth/weight/discards/interleaves 22/4096/0/2534
                 Conversation 195, linktype: ip, length: 1502
                 source: 10.1.2.2, destination: 171.68.56.138, id: 0x2DB0, ttl: 31,
                 TOS: 0 prot: 6, source port 1503, destination port 1045

                        weight/discards/interleaves) 1/128
                 (depth/weight                          128/0/0
                 Conversation 264, linktype: ip, length: 66
                 source: 10.1.2.2, destination: 171.68.56.138, id: 0xF4B0, ttl: 31,
                 TOS: 0 prot: 17, source port 49608, destination port 49608




1171_04F8_c1                                                                          62
               RTP Header Compression
                                                                                        Overhead
                                                                                 • 20ms@8kb/s yields 20
    Version             IHL    Type of Service            Total Length             byte payload
                    Identification               Flags         Fragment Offset
         Time to Live             Protocol                Header Checksum        • IP header 20; UDP
                                     Source Address                                header 8; RTP header 12
                                 Destination Address
                                                                                     2X payload!!!!!!!!
                              Options                               Padding

                   Source Port                           Destination Port        • Header compression
                     Length                                Checksum                40Bytes to 2-4 much of
    V=2        P    X     CC M         PT                Sequence Number
                                                                                   the time
                                        Timestamp
                          Synchronization Source (SSRC) Identifier
                                                                                 • Hop-by-Hop on
                                                                                   slow links
                                                                                 • CRTP— Compressed
                                                                                   Real-time protocol



1171_04F8_c1                                                                                                63
               Suggestions for Use?
                  •IP precedence
                    Network telephony
                    Audio/whiteboard conferencing
                  •RSVP
                    Videoconferencing
                  •Either
                    Interactive applications
                    Transaction applications
                    SNA in TCP/IP

1171_04F8_c1                                        64
               Agenda
                •Intended VoIP Applications
                •VoIP Introduction
                •Packet Networking Challenges
                •Cisco QoS Toolkit
                • Voice Network Design Issues
                •Network Design Examples

1171_04F8_c1                                    65
               Network Design

                  •Traffic engineering
                  •Route replacement
                  •OPX/tie line transmission
                    Tandem encoding

                  •Virtual switching
                    Dial plan integration


1171_04F8_c1                                   66
               Traffic Engineering
               Fundamentals

                   •Grade of service
                      % of calls blocked

                   •Traffic load
                      quantity of traffic during BH

                   •Quantity of circuits
                      Traffic tables


1171_04F8_c1                                          67
               PBX Review/Introduction
                           Out Bound
                           Trunk Group



                           PBX


                          ARS            PSTN



                      ?

1171_04F8_c1                                    68
               PBX Route Replacement
                       Out Bound         Back
                       TG 1
                                         Bone

                                         QoS
                 PBX
                                         WAN
                               V                   V

                 ARS                                   PBX

                                        PSTN

                       Out Bound
                       TG 2

                                   A.K.A Toll Bypass


1171_04F8_c1                                                 69
               Route Replacement
                                                IP Bandwidth
           Billing Cycle Cost ($)


                                                Tie Trunk
                                                DDD
                                                “A” Plan




                                    5      10         15       20   25   30   35
                                        Usage/Billing Cycle (Hours/Month)
1171_04F8_c1                                                                       70
               OPX/Tie Line Transmission


                                      KTS/
                                      PBX
                                  V


        PBX                 QoS       KTS/
                                      PBX
                   V        WAN   V


                                      KTS/
    Calling Patterns to               PBX
    avoid Tandem Encoding         V




1171_04F8_c1                                 71
               Virtual Switching


                                             V


        PBX                 QoS
                    V       WAN              V


                                                 KTS/
                                             V   PBX


                         Dial Plan Integration



1171_04F8_c1                                            72
               Example Network Config.
                                                    x8nnn
                            Coachman         +19782448nnn
                   Midge
                                       Highlander

                                                                  x6nnn
                     V                                            x7nnn
                                                               Tie Trunk
                                                                   DA=2

        X1nnn
                                                             tg1
                   Mayfly                                   DA=9


                                                                   PSTN
                     V




1171_04F8_c1                                                               73
               Basic Dial-Peer Configuration
    x1121                       Midge                                   Mayfly                       x1231


                FXS 1/1/0-1
                                                        IP                             FXS 2/1/0-1
                                   V                 Network               V
    x1122                                                                                            x1232

                              10.3.0.1                                     10.5.0.1
                         !                                   !
                         dial-peer voice 10 pots             dial-peer voice 10 voip
                          group 10                            group 10
                                                                                           network-peer
                          destination-pattern +19782441121    destination-pattern 197824411..
                          port 1/1/0                         session target ipv4:10.3.0.1
                         !                                   !
                         dial-peer voice 11 pots             dial-peer voice 11 pots
                          group 11                            group 11
  local-peer              destination-pattern +19782441122    destination-pattern +19782441231
                          port 1/1/1                          port 2/1/0
                         !                                   !
                         dial-peer voice 20 voip             dial-peer voice 20 pots
                          group 20                            group 20
                          destination-pattern 197824412..     destination-pattern +19782441232
                         session target ipv4:10.5.0.1         port 2/1/1
                         !                                   !
                         num-exp 1231 19782441231            num-exp 1121 19782441121
                         num-exp 1232 19782441232            num-exp 1122 19782441122



1171_04F8_c1                                                                                              74
               Example Network Config.
                                                            x8nnn
                            Coachman                 +19782448nnn
                   Midge
                                            Highlander
          x1121                10.6.0.1
                                                                          x6nnn
                     V                                                    x7nnn
                                                                       Tie Trunk
                                          10.6.0.2                         DA=2
          x1122


                                                                     tg1
                   mayfly                                           DA=9
                                   Call Completes
          x1231
                                   HS to HS                                PSTN
                     V


          x1232




1171_04F8_c1                                                                       75
               Network Peers               !
                                           dial-peer voice 21 voip
                                           group 21
                                           destination-pattern 9… … … ..
                x1121           10.3.0.1
                                           session target ipv4:10.6.0.2
                                           !
                                           dial-peer voice 22 voip
                  FXS 1/1/0-1              group 22
                                   V       destination-pattern 8...
                                Midge      session target ipv4:10.6.0.2
                                           !
                x1122                      dial-peer voice 23 voip
                                           group 23
                x1121           10.5.0.1   destination-pattern 6…
                                           session target ipv4:10.6.0.2
                                           !
                                           dial-peer voice 24 voip
                  FXS 2/1/0-1
                                   V       group 24
                                Mayfly     destination-pattern 7…
                                           session target ipv4:10.6.0.2
                x1122                      !
1171_04F8_c1                                                               76
               Configure Highlander

          Coachman
                                          !
                             Highlander
                                          controller T1 0
                10.6.0.1
                                           framing esf
                                           clock source line primary
                                           linecode b8zs
                           10.6.0.2        pri-group timeslots 1-24
                                          !


     ISDN PRI or CAS Group



1171_04F8_c1                                                           77
               Configure Highlander
                                          !
                                          dial-peer voice 6 pots
                                                               +6...
                                           destination-pattern +6...
                                           port 0:D
          Coachman
                                           prefix 2,6
                                          !
                             Highlander
                                          dial-peer voice 7 pots
                10.6.0.1                                       +7...
                                           destination-pattern +7...
                                           port 0:D
                                           prefix 2,7
                                          !
                           10.6.0.2       dial-peer voice 8 pots
                                                               +8...
                                           destination-pattern +8...
                                           port 0:D
                Local Dial Peers          prefix 8
                                           !
                                          dial-peer voice 9 pots
                                                               +9…
                                           destination-pattern +9… … … ..
                                          port 0:D
                                          prefix 9,
                                          !
1171_04F8_c1                                                                78
               Configure Highlander

          Coachman
                                          !
                             Highlander   dial-peer voice 112 voip
                10.6.0.1
                                           destination-pattern 112.
                                           session target ipv4:10.3.0.1
                                          !
                                          dial-peer voice 123 voip
                           10.6.0.2
                                           destination-pattern 123.
                                           session target ipv4:10.5.0.1
                                          !
               Network Dial Peers



1171_04F8_c1                                                              79
               Example Network Config.
                                                            x8nnn
                            Coachman                 +19782448nnn
                   Midge
                                            Highlander
          x1121                10.6.0.1
                                                                          x6nnn
                    V                                                     x7nnn
                                                                       Tie Trunk
                                          10.6.0.2                         DA=2
          x1122


                                                                     tg1
                                                                    DA=9
                   Mayfly

          x1231                                                            PSTN
                    V


          x1232




1171_04F8_c1                                                                       80
               QoS and CODEC options
                                   midge(config-dial-peer)#req-qos ?
                                   midge(config-dial-peer)#acc-qos ?
                                    best-effort       Best Effort
                                    controlled-load Controlled Load
                                    guaranteed-delay Guaranteed Delay



          midge(config-dial-peer)#ip precedence ?
           <0-7> Packet IP precedence value



                         midge(config-dial-peer)#codec ?
                          g711alaw G.711 A Law 64000 bps
                          g711ulaw G.711 u Law 64000 bps
                          g729r8    G.729 8000 bps

1171_04F8_c1                                                            81
               Dial-Peer FAX

               midge(config-dial-peer)#fax ?
                14400 FAX 14400 bps
                2400 FAX 2400 bps
                4800 FAX 4800 bps
                7200 FAX 7200 bps
                9600 FAX 9600 bps
                disable Disable Fax Relay
                voice Highest possible speed allowed by voice rate




1171_04F8_c1                                                         82
               Voice Port Configuration
    midge(config-voiceport)#cptone ?                    midge(config-voiceport)#ring frequency ?
     australia      locale                               25 ring frequency 25 Hertz
     brazil         locale                               50 ring frequency 50 Hertz
     china          locale
     finland        locale
     france         locale
     germany         locale
     japan           locale
     northamerica locale                                 Midge
     unitedkingdom locale
                                          FXS 1/1/0-1
                                                           V




    midge(config-voiceport)#impedance ?                 midge(config-voiceport)#signal ?
     600c 600 Ohms complex                               groundStart Ground Start
     600r 600 Ohms real                                  loopStart Loop Start
     900c 900 Ohms complex
     c1 complex 1
     c2 complex 2


1171_04F8_c1                                                                                 83
               Voice Port Configuration Midge
                                                                              Analog Info Follows:
                                                                              Region Tone is set for northamerica
                                                                              Currently processing Voice
                                                                              Maintenance Mode Set to None (not in mtc mode)
    Foreign Exchange Station 1/1/0 Slot is 1, Sub-unit is 1, Port is 0        Number of signaling protocol errors are 0
    Type of VoicePort is FXS                                                  Impedance is set to 600r Ohm
    Operation State is DORMANT
    Administrative State is UP
    The Last Interface Down Failure Cause is Administrative Shutdown
    Alias is NULL                                                                                     Midge
    Noise Regeneration is enabled
    Non Linear Processing is enabled
    Music On Hold Threshold is Set to -38 dBm                                      FXS 1/1/0-1
    In Gain is Set to 0 dB                                                                               V
    Out Attenuation is Set to 0 dB
    Echo Cancellation is enabled
    Echo Cancel Coverage is set to 16 ms
    Connection Mode is normal
    Connection Number is
    Initial Time Out is set to 10 s
                                             Voice card specific Info Follows:
    Interdigit Time Out is set to 10 s
                                              Signal Type is loopStart
                                              Ring Frequency is 25 Hz
                                              Hook Status is On Hook
                                              Ring Active Status is inactive
                                              Ring Ground Status is inactive
                                              Tip Ground Status is inactive
                                              Digit Duration Timing is set to 100 ms
                                              InterDigit Duration Timing is set to 100 ms
                                              Hook Flash Duration Timing is set to 600 ms

1171_04F8_c1                                                                                                              84
               Q&A



1171_04F8_c1         85
1171_04F8_c1   86

				
DOCUMENT INFO
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posted:4/26/2012
language:English
pages:86
Description: Intended VoIP Applications •VoIP Introduction •Packet Networking Challenges •Cisco QoS Toolkit •Voice Network Design Issues •Network Design Examples