No Audio is Reported on a Stream

Problem

A call completes correctly (signaling is completed), but the media (audio) stream expected to flow through the packet gateway fails.

Solution

Locate the failed terminations and gates.

1. Acquire the relevant gate IDs termination IDs using the show services pgcp gates command.
2. Display the H.248 parameters for the termination.
   user@sp-pg-router> show services pgcp terminations termination-prefix h248 ip/4/vif-0/2 vpg-1

   Termination information:
   ip/4/vif-0/2 {
         MEDIA {
           TERMINATIONSTATE { SERVICESTATES = INSERVICE },
           STREAM = 1 {
             LOCALCONTROL { MODE = SENDRECEIVE,
                            DS/DSCP = 00,
                            TMAN/MBS = 0,
                            TMAN/PDR = 0,
                            TMAN/POL = OFF,
                            TMAN/SDR = 0,
                            MGCINFO/DB = 00,
                            GM/RSB = ON,
                            GM/SAF = OFF,
                            GM/SPF = OFF,
                            GM/SPR = 0,
                            GM/ESAS = OFF,
                            GM/ESPS = OFF,
                            GM/LSP = 0 },
             LOCAL {
   v=0
   c=IN IP4 3.99.99.100
   m=- 1024 RTP/AVP -
   b=AS:0
             },
             REMOTE {
   v=0
   c=IN IP4 3.0.0.1
   m=- 20002 RTP/AVP -
   b=AS:0
             }
           }
         },
         EVENTS = 1001 { NT/QUALERT { TH = 99, STREAM = 1 } },
         SIGNALS
       }
   
   

3. Display information about the gate.
   user@sp-pg-router> show services pgcp gates 4295033088

   Gate information:
   Gate id: 4295033088          
   Gate state:  active 
   Action: forward      
   Service set id: 1     
   Media card: sp-1/2/0                                                
   Media handler: vpg1_pgcp-svc-set                                          
   Termination-id-string: ip/4/vif-0/2      
    

Using the preceding information, review and verify the following:

1. Terminations are in the In-Service state.

   If the termination is in the Out-of-Service state, no streams are allowed access to the termination. The Out-of-Service state indicates a problem with either the resources on the packet gateway or incorrect parameters requested by the PGC.

2. The termination H.248 parameters are as expected.

   Pay special attention to the LOCAL and REMOTE parameters, and make sure they are aligned with the Session Description Protocol (SDP) offered by both elements participating in the session. Also, missing or unknown values suggest a problem with the call setup initiated by the PGC.

3. Gate actions are in the Forward state.

   If one or all gates are in the Drop state, no stream is allowed to flow through it, so one-way or no audio results. If a gate is not in the Forward state, the PGC might have failed to provide a required descriptor.

   Gate actions in the Forward state, but no media is flowing (frame count is zero or not advancing), can be caused by one of the following problems:

   • Networking or routing issues, including:
     • Stream fails to reach the router. A problem exists with the network path between the stream originator and the packet gateway gates.
     • Routing Engine or PIC failure. The stream reaches the router, but the PIC fails to receive the stream. Use the show services pgcp active-configuration command to review the PIC status, and make sure that it is In-Service.
   • Hardware or element failure. The originator fails to send the stream. Use the debug tools available on the VoIP element to verify that the streams have left the element.
   • The originator is using a different source IP address than the one reported in the H.248 termination. Verify that the H.248 termination information matches the stream source and destination received by the packet gateway and the PIC. You can use the capture feature on the router to verify that the streams are received on the Packet Forwarding Engine.

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