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DHCP Failover
The DHCP Failover protocol is used to synchronize IP address leasing information between two DHCP servers, providing high availability and load sharing in enterprise networks. It allows DHCP services to remain operational even if one server fails, enabling continuous network connectivity for clients..
The DHCP Failover protocol facilitates communication and synchronization between two DHCP servers managing the same network segment. Its main objective is to maintain consistent lease states, manage load sharing, and provide redundancy. This is critical in enterprise environments, where DHCP address allocation continuity is essential.
The protocol uses a TCP-based session to exchange lease state changes, configuration updates, and keep-alive messages. It supports different failover modes, notably 'load balancing' and 'hot standby'. Load balancing splits lease assignments across servers, while hot standby designates a primary and a secondary server to minimize service interruptions during failover.
Implemented via port 847/TCP, the DHCP Failover protocol is standardized to ensure interoperability between compliant DHCP server implementations. Key data structures include lease ownership states, timers for state transitions, and conflict resolution policies to maintain a coherent lease database between servers.