Hi Perry,
On 12/5/20 12:48 PM, Perry Hutchison wrote:
After power-cycling the device, it reported that its IP address had
changed back to 192.168.0.10, and it is now found:
$ scanimage -L
device `pixma:MF4800_192.168.0.10' is a CANON Canon i-SENSYS MF4800 Series
multi-function peripheral
Question: Since link-local addresses in 169.254.0.0/32 seem to be
every bit as local as addresses on the local subnet, would it make
sense for SANE to search for networked scanners on 169.254.0.0/32
in addition to the local subnet?
The short answer is "no".
The long answer follows.
1. Actually SANE doesn't search for devices by itself. Devices are
discovered by Avahi, SANE only uses result of this discovery.
2. There is no other effective method to search for scanners and other
devices on LAN, except what Avahi does (sending discovery multicasts,
gathering replies and so on). Brute-force scanning all addresses in the
range is very ineffective, generates a lot of network traffic and may
even cause some devices, connected to that network, to hung.
3. Avahi actually does its work well. But there are many things that
affects discovery. For example, if device is not reachable due to
routing configuration, it will not be discovered.
4. This case is DHCP failure. SANE makes reasonable assumption that
network infrastructure is properly configured. It is not (and should be
not) a part of SANE responsibility to workaround network infrastructure
miss-configuration.
--
Wishes, Alexander Pevzner ([email protected])
