Neighbor detection populates the 1-hop neighbor repository and only uses the main addresses of nodes. As seen in the previous section, the neighbor entries are closely related to the link entries. Whenever a link entry is created, the neighbor table is queried for a corresponding neighbor entry. Note that this neighbor entry must be registered on the main address of the node. If no such entry can be located, then a new neighbor entry is created. This means that while a node can have several link-entries describing different links to the same neighbor, only one neighbor entry exists per neighbor.
The status of the neighbor entries is also updated according to changes in the link-set. A neighbor is said to be a symmetric neighbor if there exists at least one link-entry in the link set connecting a local interface to one of the neighbors interfaces where the symmetric timer is not timed out. When a link-entry is deleted, the corresponding neighbor entry is also removed if no other link entries exist for this neighbor.