Bloat » Cerowrt

Seems likely this is some sort of SNMP broadcast protocol being used to discover the printers on the network, according to CUPS documentation.

http://www.cups.org/documentation.php/network.html

Just to verify, the jetdirect protocol itself, works across the networks, it's just discovery that is borked?

I note that guests should NOT be able to access printer resources on the secure lan.

As for addressing this:

samba can run on the router, providing a central rendezvous point for printer information.
mdns - if implemented, and I thought it was in cups LONG ago, should also be able to do the trick,
but this would be a good test.

It's the discovery of the printer (via snmp broadcast) that seems to be the problem here, if I read my tea leaves right. The cups configuration stuff on Linux (and maybe mac) seems to use it to find printers when configuring a new printer.

To confirm this theorya, we need to do a little bit of wire sniffing.

This begs the question of how common this use of snmp broadcast is in other applications and operating systems.