[avahi] localhost service discovery in offline mode

[Remi Emonet]

Hi all,

I started using avahi more that 2 or 3 years back, mainly exploiting the 
dns-sd aspect (service discovery). Avahi is working pretty well but I 
have one case where it has a behavior that I do not expect. I hope this 
mailing list is the right place for this (or should I rather use the bug 
tracker even for non-bugs?).

Here is the "problem": the computer is connected to a local network, it 
publishes some services and is able to discover services on other 
computers (no problem here), but, if I unplug the network cable (or 
disable the local network connection) all services disappear, including 
the ones declared on localhost. In our context, we would have liked to 
keep the service discovery functionality even if the host is totally 
isolated.
Does anyone sees any way to tell avahi to continue working even if only 
the loopback interface is "connected"?
Don't hesitate to tell me if the objective or my problem is not clear.

Here is a simple way to illustrate my point:
  - have a network connection
  - in terminal T1, start "avahi-browse    _lo._tcp"
  - in terminal T2, start "avahi-publish-service   Heeere    _lo._tcp    
8888"
-> in T1 you get: "+ eth0 IPv4 Heeere  _lo._tcp  local"
  - unplug the network cable (or disable the corresponding interface)
-> in T1 you get: "- eth0 IPv4 Heeere  _lo._tcp  local"
--> This means the services on localhost cannot discover each others 
anymore.

My current test configuration is an Ubuntu 10.04 LTS 64 bits, but I have 
seen the same behavior with (all) other linux systems I've used before.

Thank you in advance for any help and comments you could provide.
Best Regards,
Rémi