do I have right understanding please

Wed Jun 24 10:35:23 PDT 2009

hi Michael,
Thank you for guidance on the protocol directives.
Also, thanks for the status of Avahi and CUPS, and about
SNMP / IPP delta from V1.2, and how to override. Very cool!

I imagine the current CUPS mDNS/DNS-SD backend really is Bonjour.

I found this post from the distant past-
"...The plan was to include the mdns backend with CUPS 1.3.x, but it was
not ready for public consumption in time.  It will likely show up in
1.4.x once we have all of the issues ironed out."

I gather that things change and now mdns backend is really here in V1.3 as Bonjour.

Idiot me, really, to think I must push 'Find New Printers' with such technology,
right? It is not required by design I would think (or try to think).
The protocol appears on the wire at CUPS scheduler startup with the expected
mDNS multicast broadcast to 224.0.0.251 IPv4 (ff02::fb IPv6), provided that you share printers from CUPS.

I discovered so this morning when I booted...ooooooppps LOL!!

I now have "something to sink my teeth into" :)

Please pardon my apparently sloppy initial analysis of mDNS protocol on CUPS.

Have a great day, and thanks again.

>
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> On Jun 23, 2009, at 3:25 PM, star wrote:
> > ...
> > 1. If so, is there a reason to even have a BrowseProtocols directive?
> > How does it cooperate with those other two directives?
>
> BrowseProtocols came first and sets both the local and remote =20
> protocols to the same value(s).  BrowseLocalProtocols and =20
> BrowseRemoteProtocols came later to set the protocols separately.
>
> > 2. The CUPS V1.3 =91Whats New=92 states that SNMP lookups are no =
> longer =20
> > performed by default. However, when I click =91Find New Printers=92 in =
> =20
> > CUPS web admin, I discover by SNMP. So, I disabled SNMP in /etc/cups/=20=
>
> > snmp.conf and now get no printers.
>
> That's likely a distribution-specific change.
>
> > But my Linux computer runs Avahi (mDNS/DNS-SD) and discovers my =20
> > network printers ok.
> >
> > Is there a way to config CUPS V1.3 to discover via mDNS/DNS-SD =20
> > instead of SNMP?
>
> Currently we do not support Avahi in CUPS, mainly because Avahi is =20
> tied to glib's run loop which is incompatible with what we use in the =20=
>
> scheduler. Tim Waugh (Red Hat) has been working on the necessary =20
> changes to make it work, but that won't appear in CUPS until 1.5 at =20
> the earliest.
>
> Till K. did an Avahi-based backend to support discovery and printing =20
> to network printers; I'm not sure what the status of that backend is.
>
> > 3. The CUPS V1.3 =91Whats New=92 states "IPP is not used for =
> discovered =20
> > printers".
> > I cannot make sense from that phrase. Can anyone clarify?
>
> The SNMP backend used to try using IPP with network printers. =20
> Unfortunately, doing so can actually lock up some network printers =20
> because of bugs in their implementation, so we no longer try IPP by =20
> default. However, you can specify DeviceURI lines in snmp.conf to =20
> force IPP, and printers that support the Port Monitor MIB can (in CUPS =20=
>
> 1.4) specify IPP as well.
>
> ________________________________________
> Michael R Sweet, Senior Printing System Engineer
>
>
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> <html><head></head><body style=3D"word-wrap: break-word; =
> -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; =
> "><div><div>On Jun 23, 2009, at 3:25 PM, star wrote:</div><blockquote =
> type=3D"cite"><div>...<br>1. If so, is there a reason to even have a =
> BrowseProtocols directive?<br>How does it cooperate with those other two =
> directives?<br></div></blockquote><div><br></div>BrowseProtocols came=
>  first and sets both the local and&nbsp=
> ;remote protocols to the same value(s). &nbs=
> p;BrowseLocalProtocols and BrowseRemoteProtocols came =
> later to set the protocols separately.</div><div>=
> <br><blockquote type=3D"cite"><div>2. The CUPS V1.3 =91Whats New=92 =
> states that SNMP lookups are no longer performed by default. However, =
> when I click =91Find New Printers=92 in CUPS web admin, I discover by =
> SNMP. So, I disabled SNMP in /etc/cups/snmp.conf and now get no =
> printers.<br></div></blockquote><div><br></div>That's likely a =
> distribution-specific change.</div><div><br><blockquote =
> type=3D"cite"><div>But my Linux computer runs Avahi (mDNS/DNS-SD) and =
> discovers my network printers ok.<br><br>Is there a way to config CUPS =
> V1.3 to discover via mDNS/DNS-SD instead of =
> SNMP?<br></div></blockquote><div><br></div>Currently we do not support =
> Avahi in CUPS, mainly because Avahi is tied to glib's run loop which is =
> incompatible with what we use in the scheduler. Tim Waugh (Red Hat) has =
> been working on the necessary changes to make it work, but that won't =
> appear in CUPS until 1.5 at the earliest.</div><div><br></div><div>Till =
> K. did an Avahi-based backend to support discovery and printing to =
> network printers; I'm not sure what the status of that backend =
> is.</div><div><br></div><div><blockquote type=3D"cite"><div>3. The CUPS =
> V1.3 =91Whats New=92 states "IPP is not used for discovered =
> printers".<br>I cannot make sense from that phrase. Can anyone =
> clarify?<br></div></blockquote><div><br></div>The SNMP backend used to =
> try using IPP with network printers. Unfortunately, doing so can =
> actually lock up some network printers because of bugs in their =
> implementation, so we no longer try IPP by default. However, you can =
> specify DeviceURI lines in snmp.conf to force IPP, and printers that =
> support the Port Monitor MIB can (in CUPS 1.4) specify IPP as =
> well.</div><div><br></div><div>
> <span class=3D"Apple-style-span" style=3D"border-collapse: separate; =
> color: rgb(0, 0, 0); font-family: Monaco; font-size: 12px; font-style: =
> normal; font-variant: normal; font-weight: normal; letter-spacing: =
> normal; line-height: normal; orphans: 2; text-align: auto; text-indent: =
> 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: =
> 0px; -webkit-border-horizontal-spacing: 0px; =
> -webkit-border-vertical-spacing: 0px; =
> -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: =
> auto; -webkit-text-stroke-width: 0px; "><span class=3D"Apple-style-span" =
> style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
> Helvetica; font-size: 12px; font-style: normal; font-variant: normal; =
> font-weight: normal; letter-spacing: normal; line-height: normal; =
> orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; =
> widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; =
> -webkit-border-vertical-spacing: 0px; =
> -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: =
> auto; -webkit-text-stroke-width: 0px; "><div style=3D"word-wrap: =
> break-word; -webkit-nbsp-mode: space; -webkit-line-break: =
> after-white-space; =
> "><div><div>________________________________________</div><div>Michael R =
> Sweet, Senior Printing System Engineer</div></div></div></span></span>
> </div>
> <br></body></html>=
>
> --Apple-Mail-3--930082340--
>