How do I relay the Common UNIX Printing System (CUPS) traffic across multiple subnets on my network without using polling?

Common UNIX Printing System (CUPS) provides a BrowseRelay directive that enables client systems to relay polled printer information to the local subnet.

For instance, a CUPS server is on subnet 1, while the clients are on subnets 2 and 3. To provide the server's printer queues to all of the clients in subnets 2 and 3, a system on each subnet can be configured with the follo...