Implementing Advanced Media Tracing and PCAP Capture Pipelines via the Edge API

How-To-Articles
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Implementing Advanced Media Tracing and PCAP Capture Pipelines via the Edge API

What This Guide Covers

  • Architecting an automated packet capture (PCAP) and media tracing pipeline for Genesys Cloud Edges (both Cloud and BYOC Premise) using the Platform API.
  • Executing remote diagnostics to troubleshoot complex, intermittent voice quality issues (e.g., one-way audio, jitter, SIP ladder failures) without requiring SSH access to the physical appliance.
  • The end result is a streamlined DevOps workflow where support engineers can trigger and download precise SIP and RTP traces directly from the Edge, accelerating root-cause analysis for carrier interoperability issues.

Prerequisites, Roles & Licensing

  • Licensing: Genesys Cloud CX 1, 2, or 3.
  • Permissions: Telephony > Edge > View, Telephony > Edge > Diagnostics.
  • Infrastructure: A backend script (Python/Node.js) or Postman collection to sequence the API calls.

The Implementation Deep-Dive

1. The Challenge of SIP/RTP Troubleshooting

When users report “garbled audio” or “calls dropping after 30 seconds” on BYOC trunks, the issue is almost always at the network layer (e.g., firewall ALG interference, NAT traversal failures, or carrier SDP mismatches).

The Trap:
To prove the carrier is at fault, you need a Wireshark PCAP file. For BYOC Premise Edges, legacy telecom engineers often try to plug a laptop into a mirror port on the physical switch. For BYOC Cloud Edges, you physically cannot span a port because you don’t own the AWS infrastructure. Both approaches are flawed. The modern solution is to command the Edge software to capture its own traffic natively via the API.

2. Initiating a Diagnostic Trace

The Genesys Cloud Edge API allows you to start a background trace on specific network interfaces or matching specific SIP Call-IDs.

Implementation Steps:

  1. Identify the Edge ID: First, query GET /api/v2/telephony/providers/edges to find the UUID of the Edge handling the problematic trunk.
  2. Start the Trace: Send a POST request to /api/v2/telephony/providers/edges/{edgeId}/diagnostics/trace.

Payload Example:

{
  "traceType": "SIP",
  "interfaceName": "eth0",
  "durationSeconds": 60,
  "filterParameters": [
    {
      "name": "ipAddress",
      "value": "192.168.1.50"
    }
  ]
}

Architectural Reasoning: Always restrict the trace by IP Address or interface. If you run a promiscuous trace on a heavily loaded Edge handling 3,000 calls, the resulting PCAP file will be gigabytes in size, impossible to open in Wireshark, and you risk maxing out the Edge’s disk I/O, causing further audio degradation.

3. Monitoring and Downloading the PCAP

The trace runs asynchronously. You must poll for completion and then retrieve the file.

Implementation Steps:

  1. Poll Status: Query GET /api/v2/telephony/providers/edges/{edgeId}/diagnostics/trace/{traceId}. Check the status field.
  2. Retrieve the URI: Once the status is COMPLETE, the API response will include a downloadUri. This URI points to a temporary, pre-signed Amazon S3 bucket URL.
  3. Download the File: Perform an HTTP GET against the downloadUri to pull the .pcap or .zip file to your local machine.
  4. Decrypting (If necessary): If you are capturing SRTP traffic, the media is encrypted. You will only see the SIP signaling in plaintext. To decode the audio, you must also extract the SRTP Master Keys from the Edge logs (which requires a Genesys Support ticket for Cloud Edges, or accessing the srtp_keys log on Premise Edges).

Validation, Edge Cases & Troubleshooting

Edge Case 1: The “Missed the Event” Timing Issue

  • The Failure Condition: Intermittent one-way audio happens randomly twice a day. By the time the user reports it, the call is over. Running a 60-second trace now yields nothing useful.
  • The Root Cause: The trace must be running while the failure occurs.
  • The Solution: Implement a Continuous Ring-Buffer Trace. Instead of a 60-second burst, write a script that starts a trace, stops it after 15 minutes, downloads it, and immediately starts another. Keep the last 4 PCAP files (1 hour of history) and delete the rest. When the user reports the issue, stop the script and analyze the most recent file.

Edge Case 2: BYOC Cloud SIP Ladder Limitations

  • The Failure Condition: You capture a trace on a BYOC Cloud trunk, but you only see traffic between the Edge and the AWS Network Load Balancer (NLB). You cannot see the public IP of the Carrier’s SBC.
  • The Root Cause: BYOC Cloud architecture abstracts the public internet edge. The Edge appliance sits in a private VPC and talks to the carrier via an AWS NLB.
  • The Solution: You cannot natively PCAP the public side of the AWS NLB. You must rely on the Genesys Cloud Interaction Details → PCAP download feature (if enabled for the org) or ask the Carrier to provide the trace from their ingress SBC. The Edge-level trace is only useful for verifying what the Edge sent to the NLB.

Official References