If you have the right sort of routers connecting your subnets, you can extend broadcasts between subnets, using either "helper" settings, or by enabling "Directed broadcast" support.

 

Having support for UDP broadcast propogation between networks enabled on routers by default is now deprecated, you will have to make this setting yourself, with a full understanding of the risks of enabling broadcast propogation. A few years ago, Cisco routers were shipped with directed broadcast support enabled, and a bunch of bad people developed the "smurf" attack, which exploited this feature to launch denial-of-service attacks.

 

Before enabling directed broadcast support on a network which is connected to the internet, ensure your border routers comply with the advice given in the best practice document RFC2827

 

Point your network manager at Cisco - UDP Broadcast Flooding

FAQ

FAQ