SS7IP Gateway Architecture by yyc62487

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									         SIP / ISUP interconnection
                                Gonzalo Camarillo
                               Gonzalo.Camarillo@ericsson.com


                                               ASRL
                               Advanced Signalling Research Lab.
Gonzalo Camarillo                           Fall ‘99 VON
Atlanta September 28th, 1999              VON protocols - SIP      Advanced Signalling Research Lab.
                               Telephone Services
      •GSTN (General Switched Telephone Network)
      •IP Telephony




                     IP Telephony                         GSTN
Gonzalo Camarillo                     Fall ‘99 VON
Atlanta September 28th, 1999        VON protocols - SIP     Advanced Signalling Research Lab.
                               Contents

      • Brief SS7 introduction (architecture)
      • Gateway architecture ( SG, MGC, MG )
      • ISUP - SIP interworking issues and proposed
        solutions




Gonzalo Camarillo                Fall ‘99 VON
Atlanta September 28th, 1999   VON protocols - SIP   Advanced Signalling Research Lab.
                               Different architectures
      GSTN architecture:
         Intelligence in the network
         Dumb terminals

      SIP architecture:
           Move the intelligence to the edge



Gonzalo Camarillo                       Fall ‘99 VON
Atlanta September 28th, 1999          VON protocols - SIP   Advanced Signalling Research Lab.
                               Signalling in GSTN
      Signalling in the network (between switches)
      User to network signalling



                  DSS 1                 ISUP                   DSS 1




Gonzalo Camarillo                     Fall ‘99 VON
Atlanta September 28th, 1999        VON protocols - SIP   Advanced Signalling Research Lab.
                                DSS-1
      Q. 931
           Protocol between the user and the network
           Much simpler than ISUP.

      Q. 921
           Handles the transport of the messages



Gonzalo Camarillo                Fall ‘99 VON
Atlanta September 28th, 1999   VON protocols - SIP   Advanced Signalling Research Lab.
                                Signalling in GSTN
      SS7 (System Signalling No. 7)
              Level

                               TCAP             ISUP           TUP
              4

                                  SCCP

               3
              2                                 MTP
              1


Gonzalo Camarillo                          Fall ‘99 VON
Atlanta September 28th, 1999             VON protocols - SIP         Advanced Signalling Research Lab.
                               General ISUP<->SIP Conversion
             Voice Stream
             Signalling
                                                          SG


                                                                                                       SIP Server
                               STP   ISUP/MTP
                                                               ISUP/IP
                                                                                         SIP

                                                                      SIP
                                                MGC
                                                                            IP network

                        SS7                     MGCP                                           SIP
                                                             MG                                         SIP Client
              DSS 1

                                        E1/T1                                            RTP


Gonzalo Camarillo                                 Fall ‘99 VON
Atlanta September 28th, 1999                    VON protocols - SIP                      Advanced Signalling Research Lab.
                 Architecture of the distributed gateway
                   ISUP
                                 Signalling Gateway
                                                                 IP side
                                 ISUP/IP
        GSTN side
                                                                SIP
                               Media Gateway Controller

                                   MGCP

                Voice stream                                Voice stream
                                   Media Gateway



Gonzalo Camarillo                       Fall ‘99 VON
Atlanta September 28th, 1999          VON protocols - SIP      Advanced Signalling Research Lab.
                      Signalling Gateway
              Function:
               • To find the appropriate media gateway controller
                                                 Signalling GW
                                        ISUP

                                     ISUP/IP
                                                                               ISUP/IP
                                                  ISUP/IP            ISUP/IP




                               MGC               MGC                           MGC                MGC



               MGCP            SIP MGCP        SIP         MGCP                SIP MGCP          SIP


Gonzalo Camarillo                                Fall ‘99 VON
Atlanta September 28th, 1999                   VON protocols - SIP                       Advanced Signalling Research Lab.
                                 Media Gateway
            Mapping between different voice formats

                                                   Control
                                                   Protocol



                               GSTN                           RTP




Gonzalo Camarillo                       Fall ‘99 VON
Atlanta September 28th, 1999          VON protocols - SIP       Advanced Signalling Research Lab.
                       Media Gateway Controller for
                               distributed
                             Media Gateways

             Functions
              • Actual mapping between protocols (ISUP-SIP)
              • Control the Media Gateway/s
              • Authentication, Authorization and Accounting (AAA)




Gonzalo Camarillo                  Fall ‘99 VON
Atlanta September 28th, 1999     VON protocols - SIP   Advanced Signalling Research Lab.
                           Experiences implementing
                              ISUP to SIP mapping

           • Different flavours of ISUP (message flow)
           • Overlap signalling (SAMs)
           • In band announcements and ring-back tone
           • ISUP transparency
           • Billing in forwarding situations
           • Tracing calls (malicious, SOS)




Gonzalo Camarillo                    Fall ‘99 VON
Atlanta September 28th, 1999       VON protocols - SIP   Advanced Signalling Research Lab.
                               Different message flows
               ITU ISUP message exchange during a call
                           Local                               Local
                          Exchange                            Exchange
                                               IAM
                                              ACM
                                              CPG
                                              ANM

                                        Voice Transfer
                                               REL
                                               RLC



                               ANSI ISUP: CPG before ACM
Gonzalo Camarillo                         Fall ‘99 VON
Atlanta September 28th, 1999            VON protocols - SIP      Advanced Signalling Research Lab.
                               Overlap signalling (SAMs)
      European phone numbers does not have a fixed length.
         Example:
          +358    9                  299               1
            Finland Helsinki Ericsson            Front desk

            +358                 9   299           3371
            Finland Helsinki Ericsson           Camarillo‟s

      The ingress gateway cannot know when the number is
      complete.
Gonzalo Camarillo                        Fall ‘99 VON
Atlanta September 28th, 1999           VON protocols - SIP    Advanced Signalling Research Lab.
                               Proposed solution

         Ingress gateway waits for SAMs with more digits
         a certain amount of time.

         • Timer = 0
           Heavy signalling traffic may be generated

         • Timer = 5 secs ( inter-digit timeout)
           User is not that patient

Gonzalo Camarillo                    Fall ‘99 VON
Atlanta September 28th, 1999       VON protocols - SIP   Advanced Signalling Research Lab.
                        In-band announcements and
                              ring-back tones
•„Your call is being forwarded to an automatic voice mail‟
• Ring-back tone
• Busy tone
                       Proposed solution: 183 SIP response
                                                   MG                       SIP Client
            DSS 1

                                E1/T1                         RTP




Gonzalo Camarillo                         Fall ‘99 VON
Atlanta September 28th, 1999            VON protocols - SIP    Advanced Signalling Research Lab.
                                        ISUP transparency
             Voice Stream                 (SIP bridging)
                                  SG                                     SG
             Signalling


            ISUP/MTP                                                              ISUP/MTP
                                   ISUP/IP                         ISUP/IP
                                                      SIP

          STP           MGC                                                   MGC           STP
                                             IP network
                               MGCP                                      MGCP




                          E1/T1                      RTP                      E1/T1
                                       MG                             MG

Gonzalo Camarillo                              Fall ‘99 VON
Atlanta September 28th, 1999                 VON protocols - SIP                Advanced Signalling Research Lab.
                               ISUP transparecy
                                 ( SIP bridging)

         ISUP messages in SIP bodies (MIME),
         SIP INFO method, reliable 1xx responses ...



       Trusted parties, confidentiality, ISUP flavours...



Gonzalo Camarillo                    Fall ‘99 VON
Atlanta September 28th, 1999       VON protocols - SIP   Advanced Signalling Research Lab.
                                 Billing
                               scenarious

       Isabel calls from Spain to my GSM mobile:
       +358 40 702 35 35 (Finland‟s international prefix)

       Isabel pays the call leg Spain-Finland
       I pay the call leg Finland-Atlanta

       SIP is end to end … where are the call legs??

Gonzalo Camarillo                 Fall ‘99 VON
Atlanta September 28th, 1999    VON protocols - SIP   Advanced Signalling Research Lab.
                               Tracing calls

           • SOS services ( physically closest center )
           • Malicious calls

      An IP address or a SIP URL do not give any useful
      information for catching the “bad guys”.




Gonzalo Camarillo                  Fall ‘99 VON
Atlanta September 28th, 1999     VON protocols - SIP   Advanced Signalling Research Lab.
                               Further information
                    IETF internet drafts ( www.ietf.org )
                    • draft-ietf-sigtran-mime-isup-00.txt
                     • draft-ietf-mmusic-sip-multipart-00.txt
                     • draft-zimmerer-mmusic-sip-isup-mime-00.txt
                     • draft-ietf-mmusic-sip-info-method-01.txt
                     • draft-ietf-mmusic-sip-100rel-00.txt
                     • draft-roach-mmusic-sip-provisional-media-00.txt
                     • draft-donovan-mmusic-183-00.txt
                     • draft-roach-mmusic-sip-pstn-require-header-00.txt
                     • draf-zimmerer-mmusic-sip-bcp-t-00.txt
                     • draft-roach-sip-isup-parameters-00.txt
                     • draft-camarillo-mmusic-sip-isup-bcp.txt
Gonzalo Camarillo                       Fall ‘99 VON
Atlanta September 28th, 1999          VON protocols - SIP   Advanced Signalling Research Lab.

								
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