SLP is used by devices to announce services on a local network.
Additionally it may have an unlimited number of name/value pairs, called attributes.
Scopes are simple strings and are used to group services, comparable to the network neighborhood in other systems.
Note that a special URL scheme "service:" is used by the printer.
Because of the potential unreliability of UDP, SLP repeats all multicasts several times in increasing intervals until an answer has been received.
The operation of SLP differs considerably, depending on whether a Directory Agent (DA) is in the network or not.
It is also possible to add DAs later, as they multicast a 'heartbeat' packet in a predefined interval that will be received by all other devices.
SLP contains a security mechanism, based on public-key cryptography, that allows signing of service announcements.