On Fri, Aug 28, 2020 at 7:52 PM Chris Murphy lists@colorremedies.com wrote:
The IPP Everywhere specification requires clients to support DNS-SD (mDNS is part of that) or WS-Discovery. Printers are required to support both DNS-SD and WS-Discovery. Avahi and systemd-resolved support DNS-SD, functionally equating DNS-SD and mDNS.
From the spec:
"Printers MUST publish a text (TXT) record that provides service information over mDNS. Printers that support dynamic DNS updates MUST publish separate TXT records for each domain that is updated."
I'm not completely certain, but I'm wondering whether it's possible to print IPP Everywhere at all, if DNS-SD or WS-Discovery aren't working on the client. Even having the IP address might not be enough.
I guess one way to test it would be to run the printing test case with an IPP Everywhere printer, and try to print with avahi stopped.