First, the notion that Bonjour, or ZeroConf, can’t be used across different subnets is not true.
3. Does Bonjour work between multiple subnets?
Yes. The first release of DNS Service Discovery (DNS-SD) for OS X concentrated on Multicast DNS (mDNS) for single-link networks because this was the environment worst served by IP software. Bonjour uses Dynamic DNS Update (RFC 2316) and unicast DNS queries to enable wide-area service discovery
Here I found a document which explains about setting Bonjour across multiple subnets.
So, probably what people say that **** can’t be connected over Bonjour was configuration problem.
Anyway, with common sense, whatever network program we make, we should make it using general TCP/IP stuff rather than ZeroConf or Bonjour.
Having those Bonjour available is good, but it should be supplementary than the only option.
OK. Probably I can use my old NetGear NAT device to make my own “subnet” ( mine doesn’t seem to allow subnets. Anyway it’s NAT device. However current NAT devices are so cool that I noticed some had “subnet” features to hook up multiple NATs as more intelligent hub — not router, not bridge but a simple hub + router )
NOTE : BTW, I really don’t want to use the term “router” to mean NAT device. First, NAT devices breaks traditional cross-operation model based on OSI 7 layer model. I know that some IT guys ( read as IS guys or SI guys ) think that NAT is normal device abide by OSI model, but not. In S.Korea, when such devices were introduced ( in early 1990’s I think ), they were called IP Sharing box. It’s better term to describe what the device is for and what it is. I know that some CISCO routers have some modes which work like NAT for various reason. However they are not basic genuine modes. The term NAT is more technically accurate than calling them routers. However, NAT sounds too smart or feels like that the person who made the term tried to hide the nature of the device and tried to make it something significant or new. IP sharing box is the most frank and sincere term.