Routers listen on this address for arriving Hello packets. An NLSP router extracts certain information from the adjacency database and adds locally derived information. All LSPs constructed by all routers in the routing area make up the link-state database for the area. The NLSP specification intends that each router maintain a copy of the link-state database and keep these copies synchronized with each other. The link-state database is synchronized by reliably propagating LSPs throughout the routing area when a router observes a topology change.
Flooding is instigated when a router detects a topology change.
When such a change is detected, the router constructs a new LSP and transmits it to each of its neighbors. Upon receiving an LSP, the router uses the sequence number in the packet to decide whether the packet is newer than the current copy stored in its database. The receipt-confirmation process is different for LANs and WANs. On WANs, a router receiving an LSP replies with an acknowledgment. This ensures that other routers can detect whether they are out of synchronization with the Designated Router.