BYOC Edge 504 Gateway Timeout during JMeter concurrent SIP INVITE stress test

Voice & Telephony
1

I’m completely stumped as to why my Genesys Cloud BYOC Edge deployment returns 504 Gateway Timeout errors when JMeter thread count exceeds 150 concurrent SIP INVITE requests. The environment uses Genesys Cloud v2024.2.0 and a self-hosted Edge appliance version 10.5.1. Single call scenarios work perfectly with 200 OK responses. Low load tests with 50 threads also complete successfully without any packet loss or timeout issues. The problem only appears under high concurrency spikes.

Here is the exact reproduction scenario:

  1. Configure JMeter 5.6 with a Thread Group set to 200 users, ramp-up period of 10 seconds, and loop count of 1.
  2. Add HTTP Request sampler for SIP INVITE to the BYOC Edge public IP address on port 5060.
  3. Include standard SIP headers: Via, From, To, Call-ID, CSeq, Contact, and Content-Type.
  4. Add a Constant Timer of 500ms between requests to prevent initial burst overwhelming.
  5. Execute the test plan and monitor Genesys Cloud Edge logs and JMeter response codes simultaneously.

The first 150 requests return 200 OK. Requests 151 to 200 fail with 504 Gateway Timeout after 30 seconds. No 408 Request Timeout errors occur. No 503 Service Unavailable errors appear. The Edge appliance CPU usage stays below 40% during the test. Memory usage remains stable at 60%. Network throughput does not hit saturation limits. Firewall rules allow full UDP traffic on port 5060.

I checked the Edge configuration for WebSocket connection limits. The default limit of 1000 connections seems sufficient for 200 concurrent calls. API rate limits do not apply to SIP signaling traffic. I verified the SIP trunk configuration in Genesys Cloud admin portal. All settings match the documentation for BYOC Edge deployments. The issue persists even after restarting the Edge service and clearing JMeter cache.

Can someone explain what capacity limit I am missing? Is there a hidden concurrent session limit for BYOC Edge that triggers 504 errors instead of 503? Any insights on proper JMeter pacing for SIP load testing would be appreciated. I need to validate our call capacity planning before production launch next week.