[OpenIndiana-discuss] OI IPv4 Stack setting DF flag on fragmented UDP packets

[Till Wegmüller]

Hi Markus

Nice to see you on the List :)

The First question will be who does the fragmenting and what kind of
fragment are we talking about.

If it is IP based it could also be a router on the way that fragments it.

If it is on the DNS layer then there should just be two IP packets that
should pass through a stateful firewall on the client router.

In any case you can play with the MTU with ipadm set-ifprop and ipadm
show-ifprop

It might be that the MTU is set below 1500 which is the case on my
machine. Mine is 1472 by default (no idea why, but could be automegotiation.

In any case I don't think that the Packaet Size of a DNS should be much
bigger then.

Hope this helps
Greetings
Till

On 04.12.2017 19:31, Markus Wernig wrote:
> 
>>   http://whiteboard.ping.se/Networking/DnsTcp
> 
> Yes, I can force BIND to switch to TCP by setting max-udp-size 1440, but
> that's just giving in ...
> 
>> Regardless, I expect that DNS 'named' is reponsible for setting the DF
>> flag.
> 
> Hm. On Solaris, this was also a BIND named, compiled from source with
> gcc4, and there is no compile option to influence that. So I assume it
> must be in libc somewhere.
> 
> best /markus
> 
> 
> 
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