[Dnsmasq-discuss] No DHCP leases handed on bridge interface

Albert ARIBAUD albert.aribaud at free.fr
Fri Jul 15 16:18:58 BST 2016


Le Fri, 15 Jul 2016 16:39:37 +0200
Sébastien Delafond <seb at debian.org> a écrit:

> On Jul/15, Albert ARIBAUD wrote:
> > Just to make sure: "eth0.2" would normally denote a virtual
> > interface for VLAN 2 traffic on eth0. Are VLANs involved in your
> > network setup?  
> Hi Albert,
> the hardware is an ARM board using the roboswitch module: that
> basically uses VLANs internally, in order to let users dynamically
> create logical groups from the 9 physical ethernet ports available on
> the board, by writing to /proc/switch/eth0/*. Does that help ?

That leads to further questions, at least. VLANs do not cause problems
for dnsmasq, but bridging VLANs may be tricky and more prone to network

So just to make sure, can you list all interfaces and all bridges in
your system, including ifconfig outputs?

FYI and assuming you can read French :) here is an overview of an
issue I had with bridged VLANs: <http://albert.aribaud.net/fr/node/11>.

The Englih TL;DR of it is: I had eth0 and eth1 bridged (as "br0") and
needed VLAN 100 traffic to pass across transparently. Not only did I
need to also bridge eth0.100 and eth1.100 (as "br100"), but I also
had to use iptables to make br0 reject VLAN 100 packets, otherwise they
were dropped instead of being processed and passed across by br100.

Again: no reason why your problem might be the one I had; I'm just
giving an example of how mixing bridges and VLANs can be tricky.

> Cheers,
> --Seb


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