Multiple GUPs for all the network

12.1 RU2

I have some GUPs and I want to use them for all the network. I don't want to list all the subnets in explicit gups section (let me say, such 500 subnet), ALL the network,

I want to assign all the GUPs to the entire network and I want every clients to choose the "fastest" GUPs (as reply time).

Is it possible?

Thanks!