Hi Roanne,
Please be more specific as this is a very general question, network planning is a high level design for a network infrastructure which might involve a lot of technologies.
As for Trapeze/Juniper Ring Master Software for example, the network plan is a kind of configuration domain, so maybe you will use a MASTER Ring Master software and you have many sites, each site is not connected to each other in terms of wireless, hence you can make multiple Network Plan for them , one NET-PLN for each site in order to separate the configuration for each one.
i hope this will help
BR
yasser