[avahi] Resolving many ( > 200 ) items seems to lead to apparent congestion in the dbus

Lennart Poettering lennart at poettering.net
Fri May 15 05:54:34 PDT 2009

On Fri, 15.05.09 10:17, Daniel Wynne (daniel.wynne at mobotix.com) wrote:

> Hi All!
> Since we sometimes deal with more than 250 hosts, we often run into
> timeouts from the Resolvers. For now, we immediately try again until all
> Hosts are resolved. This can take up to 10 mins...
> After restarting the application we end up resolving only about 50% of
> the hosts. A restart of the dbus allows the application to find all
> hosts again.
> Is there a knwon issue about the dbus system that "free"-ed items remain
> for an amount of time? Is there an easy workaround for this? 
> Do you think it would be good practice to establish an queue system to
> avoid the resolver-timeouts?

How are you using this? Are you resolving 250 hosts one after the

Avahi enforces limits at all places, i.e. on the cache, timeouts,
queries sent out and so on, to make sure we don't flood the network,
and that Avahi cannot be used for a DoS attack. 

mDNS is intended to be used in smaller networks, up to 200 hosts or
something like that. I.e. small offices, homes. If you have larger
networks than that mDNS is not the protocol you should be using.


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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