Zigbee is a wireless communication protocol designed for low-power, low-data rate, and secure networking. Its mesh network topology provides robustness and reliability. When a router in a Zigbee network fails, the protocol has mechanisms to deal with such failures to ensure the network remains operational. Here’s how Zigbee handles router failures:
Zigbee employs a mesh network topology, allowing each device to communicate with any other device in the network. This topology provides redundancy, as multiple paths exist for data to travel between devices. When a router fails, other nodes can reroute the data through alternative paths, maintaining network connectivity.
Zigbee uses two primary routing algorithms: Ad hoc On-Demand Distance Vector (AODV) and Many-to-One Routing.
- AODV (Ad hoc On-Demand Distance Vector): This is a reactive routing protocol where routes are created on-demand, meaning a route is only established when needed. If a route through a failed router is disrupted, AODV determines an alternative path by discovering a new route dynamically.
- Many-to-One Routing: This is typically used for communication between many nodes to a single central node, like data collection from sensors to a central controller. It simplifies the routing table by maintaining fewer routes, and if a router fails, alternative routes to the central node are quickly re-established.
When a device detects that a route is no longer valid, it initiates a route discovery process. Here’s how it happens:
- Route Discovery: The failing node broadcasts a route request (RREQ) to its neighboring nodes. These neighbors will forward the RREQ until it reaches a node with a valid route to the destination. Upon reaching the destination or a node with a fresh route, a route reply (RREP) is sent back to the originator, establishing a new path.
- Route Maintenance: Zigbee continually monitors routes’ quality and validity. Route error (RERR) messages are sent if a link breakage or failure is detected, notifying the source node to initiate a new route discovery.
Zigbee networks incorporate self-healing capabilities. When a router fails, the network automatically reorganizes itself to re-establish connectivity. Neighboring nodes can take over the communication role to ensure the network remains functional.
Zigbee’s robustness in dealing with router failures is a result of its mesh network topology, dynamic routing protocols like AODV and Many-to-One Routing, proactive route discovery, and maintenance mechanisms, all underpinned by self-healing capabilities. Thus, Zigbee ensures that even when individual routers fail, the network as a whole remains operational and resilient.
