LSP sent when:
1.A router contacts a new neighbour router
2. A link fails
3. The cost of a link changes
4. Periodically every fixed time interval
LSPs have timestamps and sequence numbers so that:
1. forwarded packets are not forwarded again
2. allow correct ack by receiver
When LSP received:
Router examines fields of the LSP: link identifier,metric,timestamp or sequence number
If LSP data not in database, data is stored and LSP is forwarded over all interfaces but the one on which it was received
Same happens if LSP data is in database, but it is more recent than data about this link contained in database.
If LSP data is less recent than data stored in database, new LSP with data stored in database is sent back only over the link from which the first LSP was received
If LSP data is the same as database data, no operation is performed.