FreeBSD 15: bhyve VM loses network after bridge reset

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Guests remain running but lose inbound and outbound connectivity, disrupting hosted workloads.

Environment & Reproduction

Observed after host network restarts, bridge membership changes, or interface flap events.

Root Cause Analysis

tap interface detaches from bridge or host filtering changes break forwarding path unexpectedly.

Quick Triage

Confirm guest state, bridge membership, and host route continuity before restarting virtual machines.

Step-by-Step Diagnosis

Inspect tap and bridge relationships plus packet counters to isolate forwarding break.

Solution – Primary Fix

Rebind tap interfaces, restore bridge configuration, and persist settings in startup scripts.

Solution – Alternative Approaches

Use dedicated vm-switch abstraction or isolated bridge per tenant to reduce blast radius.

Verification & Acceptance Criteria

Guests regain stable connectivity and survive host network restart without manual intervention.

Rollback Plan

Reapply previous bridge profile and guest launch parameters from last known-good backup.

Prevention & Hardening

Automate post-restart bridge validation and alert on missing tap membership conditions.

Related Errors & Cross-Refs

Related to pf bridge filtering defaults and VLAN trunk mismatches on uplinks.

Related tutorial: View the step-by-step tutorial for freebsd-15.

View all freebsd-15 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

bhyve and if_bridge man pages plus FreeBSD virtualization handbook guidance.