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Optimum Video Quality

The following

1. Enable RTCP relay on both legs to ensure video RTCP feedback messages are relayed.

   Code Block
   language none title Example
   % set profiles media packetServiceProfile <PSP name> rtcpOptions rtcp enable terminationForPassthrough disable

   
   
   

2. Enable SIP INFO relay and transparency depending upon the SBC release.
   
   

   1. Prior to 4.2.3R0 release: Enable SIP INFO relay and transparency for unknown bodies to allow relay of the FAST UPDATE SIP INFO.

      Code Block
      language none title Example
      % set profiles signaling ipSignalingProfile DEFAULT_SIP commonIpAttributes relayFlags info enable % set profiles signaling ipSignalingProfile DEFAULT_SIP commonIpAttributes transparencyFlags unknownBody enable

      
      
      

   2. Effective 4.2.3R0 release and onwards: Enable SIP INFO relay and transparency for media_control+xml body to allow relay of the FAST UPDATE SIP INFO.

      Code Block
      language none title Example
      % set profiles services transparencyProfile mediaControl sipMessageBody application/media_control+xml % set profiles services transparencyProfile mediaControl state enabled % set addressContext default zone <egress Zone> sipTrunkGroup <egress TG> services transparencyProfile mediaControl

      
      
      

3. If the SBC receives media packets (audio, video, FECC, and BFCP) beyond MTU size, it will increment an error counter in SYS log. An example SYS log entry is shown below.

   Code Block
   language none title Example
   140 10152012 190702.985943:1.01.00.31881.MAJOR .PRSNP: *NP 0 error counter rcvPkt2Big incremented: cnt 8749 last error 0x101203f

    

   On the other hand, if the video packet is less than MTU size but is fragmented, SBC will drop the packet. To check if the video packet is getting dropped, you can issue the following CLI command (see Show Table System for command details).

   Code Block
   language none title Check for dropped packets
   > show table system ipPolicing discardRuleOffendersList

   
   
   To verify a fragmented media packet, request for a packet capture from the switch/router directly connected to the physical media port of the SBC. Use Wireshark tool to open and view the captured file.
   
   

   1. From Wireshark, select Statistics > Flow Graph. The "Flow Graph" displays.

      Caption
      0 Figure 1 Flow Graph Dialog 3 Flow Graph Dialog

      
      
      

   2.  Click OK to display the "Graph Analysis" window.

      Caption
      0 Figure 1 Graph Analysis Window 3 Graph Analysis Window

      
      
      

   3. Scroll down to find "IPv4 fragment" or IPv6 fragment" stream. A "UDP" stream is shown after the fragment, and includes the destination port in the media UDP port range.

Late Media Support

The “convert” mode for lateMediaSupport only applies to Audio; for multimedia sessions, enable “passthru” mode.

CLI syntax to enable pass-through (see SIP Trunk Group - Media - CLI for configuration details):

set addressContext <addressContex name> zone <zone name> sipTrunkGroup <sipTrunkGroup name> media lateMediaSupport passthru