[Dnsmasq-discuss] Advertising link MTU in the RA

Simon Kelley simon at thekelleys.org.uk
Mon May 13 17:17:35 BST 2013

On 13/05/13 16:52, Yuri Pankov wrote:
> On Mon, 13 May 2013 11:01:49 +0100, Simon Kelley wrote:
>> On 10/05/13 15:26, Yuri Pankov wrote:
>>> Hi,
>>> Is there a way to specify link MTU sent in the RA (same as AdvLinkMTU
>>> option in radvd)?
>>> Running:
>>> Dnsmasq version 2.62 Copyright (c) 2000-2012 Simon Kelley
>>> Compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP DHCPv6
>>> no-Lua TFTP no-conntrack
>> The current release (2.66) sends the MTU of the server's interface
>> automatically in the RA. I'm not sure if that was added after 2.62, but
>> I think not.
>> There's no way to specify a value other that the value derived from the
>> local interface.
> Got it. I'm using HE's tunnel, which is set to 1280, and the MTU got
> from RA is 1500, despite being set to 1280 for the interface (using
> OpenWRT with 6in4 settings). I can live with that for now, setting the
> MTU manually on the laptop, but if you could add an option to configure,
> it would be awesome. And thanks for the great software :-)

The current release, 2.66 determines the MTU in a different way, which 
may fix this problem.




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