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Version: 4.0.0-incubating

MQTT Server Load Balancing

MQTT Broker nodes expose TCP / TLS / WS / WSS endpoints for MQTT 3.1.1 and MQTT 5.0 clients.
Two load-balancing approaches are available depending on deployment conditions.

L4 Load Balancing​

Use cases:

  • Horizontal distribution of client connections
  • TLS offloading at the load balancer layer

Supported balancers:
Any standard Layer-4 TCP load balancer (e.g., NGINX stream, HAProxy, AWS NLB).

Proxy Protocol Support:
BifroMQ supports Proxy Protocol v1 and v2. It allows the load balancer to forward the real client IP and port.

Non-LB Deployment​

Applicable when all clients use MQTT 5 and the environment allows brokers to instruct clients to reconnect elsewhere.

Mechanism:
BifroMQ can actively redirect clients using MQTT 5 disconnect semantics:

  • Server moved (0x9D) — permanent relocation
  • Use another server (0x9C) — temporary relocation

Redirection logic is defined by the Client Balancer Plugin, which can select target brokers based on metrics such as load, latency, or session distribution.