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The ability to capture and store RTP media streams from VoIP networks is becoming increasingly important for service providers, because the captured RTP streams are the vital resource for troubleshooting and analyzing media quality in an IP network. In the context of the Sonus GSX/SBC 9000/SBC SWe, the Media Capture Tool (MCT) serves the above purpose by allowing the monitoring of RTP streams for calls that pass through or terminate on the GSX/SBC 9000/SBC SWe. The MCT is meant to troubleshoot field issues related to the media packets flowing through the GSX/SBC 9000/SBC SWe. RFC 2833 and T.38 work correctly in both transcoded and non-transcoded scenarios. The protocols used are SIP-SIP and GW-GW. MCT tool can also be used to record using ERE.

The MCT works in conjunction with the GSX/SBC 9000/SBC SWe to capture and archive the RTP streams for specific calls. The calls that need to be monitored are specified through recording criteria on the PSX. If a call arrives at the GSX, and the recording criteria specifies that it has to be recorded, then GSX triggers the MCT to start the recording. Additionally, GSX also specifies the duration of the RTP to be captured. GSX then forks the relevant RTP streams and sends it towards the MCT for recording. The call legs that need to be monitored are configured as part of the recording criteria. For each call leg that needs to be monitored, the GSX sends two RTP streams towards the MCT;  one for the received packets (also referred to as “Rx stream”), and another for the transmitted packets (referred to as the “Tx stream”). Once the recording duration is reached, MCT terminates the RTP capture. If the recording duration is configured as infinite, the RTP capture continues until the original call is terminated. The MCT collates and stores all the RTP streams for a given call in a single folder in PCAP format for ease of access. The stored RTP streams can then be post-processed to analyze and narrow down the root cause for the network issue.

At a high-level, the MCT features include:

  • RTP captures are archived in PCAP format
  • RTP captures for a given call are collated and organized in distinct folders using an intuitive naming convention
  • Ability to specify the maximum simultaneous calls
  • Ability to limit and manage the available disk space
  • Metadata files logged with details of the RTP capture
  • Auto-restart in case of a crash (active recordings are terminated)

For more information, refer: Media Capture Tool (MCT) for Linux and OpenStack.