[avahi] Record too large, cannot send

[Harvey, Edward]

> From: avahi-bounces+edward.harvey=analog.com at lists.freedesktop.org
> [mailto:avahi-bounces+edward.harvey=analog.com at lists.freedesktop.org]
> 
> I am running Ubuntu Oneiric (beta 1) amd64, fully updated
>       netatalk 2.2~beta4-1
>       avahi-autoipd 0.6.30-4ubuntu1
>       avahi-daemon 0.6.30-4ubuntu1
>       avahi-utils 0.6.30-4ubuntu1
> 
> Trying to configure server as a time machine server.  Working great so far,
> but only up to 20.  As soon as I add the 21st share, they all disappear.  I can
> still connect to the shares via netatalk (go into Finder, type in
> afp://tmserver), but the bonjour/avahi information disappears, so the target
> no longer appears in the Time Machine "Select Disk" dialog.
> 
> When I watch the syslog with 20 versus 21 shares enabled in netatalk, the
> following is the clear differentiating factor.  At 21 users, I get this message:
> Sep 23 05:17:40 tmserver avahi-daemon[1042]: Record too large, cannot send
> 
> Any ideas how to resolve this problem?

I tracked this down through the source code, and found the AvahiDnsPacket has a property called max_size, which gets set based on the system mtu.  So I changed the system mtu (tried increasing from 1500 to 1600) and restarting avahi-daemon and netatalk...

The log message disappeared (No more avahi-daemon "Record too large, cannot send" appearing in the syslog) but the client still cannot see the server with 21 shares or more.  (Again, yes can browse afp:// but no, does not populate list via bonjour)

So I'm hoping someone might have some more useful information or suggestions...