MQTT over QUIC Bridge
EMQX Edge 1.3 introduces MQTT over QUIC Bridge, enabling EMQX Edge to use QUIC as the transport layer when bridging MQTT traffic between edge nodes and upstream brokers (such as EMQX 5.x).
QUIC is a modern transport protocol that runs over UDP and is standardized by the IETF. It integrates encryption, connection migration, and stream multiplexing by design. Compared to traditional TLS/TCP-based MQTT bridges, MQTT over QUIC offers faster connection establishment, improved stability in weak network conditions, and better latency characteristics.
With MQTT over QUIC bridging, existing devices can continue using MQTT over TCP to connect to EMQX Edge, while the edge-to-cloud MQTT bridge uses QUIC as the transport protocol, without requiring any device-side SDK upgrades.
Key Capabilities
MQTT over QUIC Bridge provides the following capabilities:
- Use QUIC as the transport layer for MQTT bridges between edge and cloud.
- Faster connection establishment with 0-RTT / 1-RTT handshakes.
- Improved stability under high latency, packet loss, or unstable networks.
- Stream-based multiplexing without TCP head-of-line blocking.
- Support for MQTT v3.1.1 and MQTT v5.
- Fine-grained control over QUIC behavior, including timeouts, RTT estimation, and congestion control.
- Priority handling for QoS 1/2 messages over QoS 0 traffic during congestion.
- A hybrid bridging mode that automatically falls back from QUIC to TLS/TCP.
Typical Use Cases
MQTT over QUIC bridging is suitable for a range of cloud-edge deployment scenarios where network conditions, device constraints, or migration requirements make traditional TCP-based bridging less effective.
Legacy Devices Without MQTT over QUIC
Many deployed devices only support MQTT over TCP and cannot be easily upgraded to newer transport protocols. MQTT over QUIC bridging addresses this limitation by introducing QUIC only on the edge-to-cloud link, while preserving the existing device connectivity model.
In a typical deployment:
- Devices connect to EMQX Edge using MQTT over TCP.
- EMQX Edge forwards messages to the upstream cloud broker using MQTT over QUIC.
With this architecture, organizations can improve cloud-edge connectivity and network resilience without modifying device firmware or redeploying device-side SDKs.
Weak or High-Latency Networks
MQTT over QUIC is well-suited for environments such as:
- Cross-region or cross-operator public networks
- Mobile networks (4G/5G, vehicle networks)
- Satellite or long-distance links with high RTT and packet loss
QUIC's fast reconnection, multi-stream capability, and advanced congestion control can significantly improve end-to-end latency stability and connectivity.
Prioritizing Critical Business Data
On bandwidth-constrained links carrying mixed workloads, QUIC can prioritize QoS 1/2 messages (such as alarms and control commands) over QoS 0 telemetry to ensure the timely delivery of critical data.
Gradual Adoption of QUIC
Hybrid bridging allows operators to prefer QUIC while retaining TLS/TCP as a fallback. This enables a smooth, low-risk migration to QUIC in production environments.
How It Works
The MQTT over QUIC Bridge consists of three components:
- Connector: Establishes the connection to the remote MQTT broker using QUIC.
- Forwards: Rules for sending messages from local topics to remote topics.
- Subscriptions: Rules for receiving messages from remote topics to local topics.
The bridge manages message queues, QoS levels, and connection lifecycles internally to ensure reliability even in challenging network environments.
What's Next
- Follow the Quick Start Guide to create your first MQTT over QUIC bridge.
- Explore the Configuration Reference to learn detailed configuration options and examples for tuning MQTT over QUIC bridges.