Presentatie Augustus by HC12061419489

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									Voice over IP
Lianne Meppelink
                 Contents
•   Introduction to VoIP
•   The Internet Call Processing Model
•   The Internet Call Processing Protocols
•   Possible directions
•   Scenario
        Introduction to VoIP
• Establishing VoIP connections with
  H.323 or SIP
• Signaling Control Information with
  MGCP or Megaco
• RTP (over UDP) is used for packet
  structure
The Internet Call Processing Model
 The User                   The Services


                Gateway
                                             Internet




                                                        Internet




                                       Internet
                                                        Gateway Controller:
            Gateway Controller                          H.323: Gatekeeper
                                                        MGCP: Call Agent
                                                        Megaco: Media Gateway
                                                        Controller
The Internet Call Processing Model (2)
                     The DNS and the Web Support Operations
    Call Processing Protocols         User Protocols                  Support Protocols

L                                   Voice    Video
        H.323, Megaco,
7                                                       Data            RTCP. NTP, SDP
          MGCP, SIP
                                       RTP

L                                                       TCP,
4           TCP, UDP                    UDP             UDP                  TCP, UDP



L
3                                      IP     RSVP    IGMP

L
1
L                                     Data Link and Physical Layers
2
The Internet Call Processing Protocols
• H.323
• The Media Gateway Control Protocol
  (MGCP)
• Megaco/H.248
• The Session Initiation Protocol (SIP)
                  Resi-
                                MGCP             Common   Accoun-
                                 Call                               Trunking
User             dential                          Data-     ting               LEC
                                Agent                               Gateway
                Gateway                           base    Gateway

                      Notification
                                   1
                       Request
                       ACK
    Offhook 2
3
                       Notify
                  4
                        ACK          5
                     Notification
       Dialtone       Request 6
                    7 ACK
                  7
8      Digits
                       Notify
                  9
                       ACK
                                     10
                      Notification
                       Request
                12     ACK

                        Create
                13
                      Connection
                14     ACK
                                15       Query

                                         Response
                                                    16
                                           Create
                                  MGCP (2)
              Resi-                     Common   Accoun-
                                 Call                        Trunking
User         dential                     Data-     ting                       LEC
                                Agent                        Gateway
            Gateway                      base    Gateway
                                                                        ANM     25
                                                       ANM
                 Notification
                              26
       Remove 27 Request
       Ringing    ACK
              27
                   Modify
                              28
                 Connection
             29   ACK
                                                                        REL     30
                                                           REL
                     Delete
                   Connection 31 Delete
                          31 Connection

             32     ACK                               ACK        32
   Onhook
                  33
             34        Notify

                       ACK         35
                         Megaco
    Local Gateway               MGC                  Remote Gateway


                     Modify
                                     1
                Modify (ACK)
         2
  Off-hook 3
                      Notify
         4                           5 Off-hook
                                       recorded
                Notify (ACK)
                                     6
Accumulate
            7
   digits             Notify
          8
                Notify (ACK)
                                     9
                      Add
                                     10
                    Add (ACK)
        11
                                            Add
                                12
                                          Add (ACK)
                                                             13

                                14          Modify
                                                          15 Ring
                                           Modify (ACK)      16
                  H.323
•   Discovery
•   Registration
•   Connection Setup
•   Capability Exchange
•   Logical Channel Exchange
•   Payload Transfer
•   Termination
                        SIP
User Agent
  – User Agent Client
  – User Agent Server
• Servers
  – Proxy
  – Redirect
  – Registrar
• Location Servers
  – Database with routing information
• SIP supports mobile users!
                        SIP (2)
               Proxy         Location        User
User 1                                                      User 2
               Server         Server         Agent

     INVITE
 1
       url          INVITE
                2
                      url

                        location   3
                         INVITE
               4
                                                     Ring
                                             5
                                        OK       6
          OK
                    7
         ACK
8                        ACK
               9
                                                   Overview
                      H.323                        SIP                          MGCP                       MEGACO
Architectural Model   Peer-to-peer                 Peer-to-peer                 Master/slave               Master/slave
Media types           Voice, video, limited data   Voice, video, data           Voice                      Voice, video
Network scope         Intra, Extra, and Internet   Intra, Extra, and Internet   Intranet only              Intranet only
Extensibility         Low                          High                         Medium                     Medium
Scalability           Medium                       High                         Low                        Low
Ease of deployment    Low                          High                         Medium                     Medium
Standardization       ITU-T                        IETF                         IETF                       IETF and ITU-T
                                                                                Signaling Control          Signaling Control
Functionality         Establishing connection      Establishing connection
                                                                                     Information                Information
                                                   Web-based, relatively
                                                       simple and easily
                      Quite prevalent and
                                                       extensible. It is        Web-based and relatively   Web-based and
Advantages                 powerful (especially
                                                       published as RFC             simple                     relatively simple
                           for conferencing)
                                                       2543, thus a formal
                                                       IETF standard
                                                                                Lots of redundancy
                      Complex and built on                                           relative to Megaco,
Disadvantages                                      -                                                       -
                          ITU-T OSI layer 6                                          but not an Internet
                                                                                     standard
         Interesting things
• SpeakUp – Florian Overkamp
• Bachelor Thesis Jesse Kaijen – DACS
  (Meent and Pras)
               Possible directions
•   Compression techniques
•   Quality improvement
•   VoIP over UMTS
•   VoIP over AdHoc Network
•   Access to emergency number 112
•   Focusing on one component (GateKeeper) and improving it
•   VoIP conferencing (multicast)
•   Improving standards (SIP, H.323)
•   Testing a program, like Skype
•   Optimization of two standards
•   Literature study to give a broad overview of VoIP
               Scenario
• Voice over IP over Bluetooth
• VoIP over WLAN -> many papers
• VOIP over BT -> only Alcatel
  – Bluephone
  – Commercial in 2005

								
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