How can service IDs be guaranteed unique?
Created May 4, 2012
Tim Rohaly
The second method, version 0x1, uses a timestamp, ethernet MAC address,
and a random number in combination. Because this second method uses
unique identifiers as part of the generated service ID, it is less likely
to produce a duplicate ID.
There are two prescribed ways to generate a service ID; they are differentiated by a four-bit field in the 128-bit service ID which identifies which of the two methods generated that ID.
The first method, version 0x4, simply uses a cryptographically strong psuedo-random number as the service ID. The algorithm is not specified. Uniqueness is guaranteed only by chance - a well-designed implementation will likely include timestamp and service name information in the seed, thus making it unlikely that two different services are assigned the same service ID.