Traps & Capture

Intermittent problems are the hardest to debug. The glitch happens once an hour—or once a day. You can't watch charts continuously, and you can't capture packets forever.

Traps solve this by watching for you. Define a threshold, and JitterTrap triggers automatically when it's exceeded.

Traps and capture controls

Sliding Window Buffer

JitterTrap captures packets continuously into a rolling buffer. Old packets are discarded as new ones arrive. The buffer holds a fixed time window—typically a few seconds.

When a trap triggers, the buffer is saved. You get the event and the seconds leading up to it.

This is different from starting a capture when you see a problem. By then, the interesting packets are gone. With a sliding buffer, they're already captured.

Creating Traps

  1. Click + Add in the Traps panel
  2. Select a condition:
    • Rx/Tx Bitrate Exceeds or Falls Below
    • Rx/Tx Packet Rate Exceeds or Falls Below
    • Packet Gap Exceeds
  3. Set the threshold value
  4. Enable Trigger packet capture to save packets when triggered
  5. Click Add Trap

You can create multiple traps with different conditions.

Trap Actions

When a trap triggers:

ActionDescription
Pause chartsFreezes the display so you can examine the event
Save captureWrites the buffer to a pcap file
Visual alertHighlights the triggered trap

Use Cases

Catching intermittent glitches:

  • Set threshold for inter-packet gap > 50ms
  • Let it run overnight
  • Come back to a pcap of exactly when and why

Validating fixes:

  • Set a trap for the condition that was failing
  • Run your updated system
  • If no trigger, the fix worked

Stress testing:

  • Combine with impairments: inject increasing delay
  • Set trap for when application-level metrics degrade
  • Find the exact threshold where your system fails

Capture Settings

SettingDescription
Buffer sizeHow many seconds/packets to keep in memory
Pre-triggerSeconds before the event to include
Post-triggerSeconds after the event to include

Export to Wireshark

Captured packets export as standard pcap files. Open them in Wireshark for:

  • Protocol decoding
  • Sequence analysis
  • Timing measurements
  • Root cause investigation

JitterTrap decides what's worth keeping. Wireshark tells you what happened.