Re: [LEDE-DEV] DHCP via bridge in case of IPv4

From: Aaron Z
Date: Sat Jul 09 2016 - 07:48:39 EST

On Sat, Jul 9, 2016 at 4:37 AM, Alexey Brodkin
<Alexey.Brodkin@xxxxxxxxxxxx> wrote:
> Hello,
> I was playing with quite simple bridged setup on different boards with
> very recent kernels (4.6.3 as of this writing) and found one interesting
> behavior that I cannot yet understand and googling din't help here as well.
> My setup is pretty simple:
> ------------- ------------------ -------------------------
> | HOST | | "Dumb AP" | | Wireless client |
> | with DHCP |<----->(eth0) (wlan0)<----->| attempting to |
> | server | | \ br0 / | | get settings via DHCP |
> ------------- ------------------ -------------------------
> * HOST is my laptop with DHCP server that works for sure.
> * "Dumb AP" is a separate board (I tried ARM-based Wandboard and ARC-based
> AXS10x boards but results are exactly the same) with wired (eth0) and wireless
> (wlan0) network controllers bridged together (br0). That "br0" bridge flawlessly
> gets its settings from DHCP server on host.
> * Wireless client could be either a smatrphone or another laptop etc but
> what's important it should be configured to get network settings by DHCP as well.
> So what happens "br0" always gets network settings from DHCP server on HOST.
> That's fine. But wireless client only reliably gets settings from DHCP server
> if IPv6 is enabled on "Dumb AP" board. If IPv6 is disabled I may see that
> wireless client sends "DHCP Discover" then server replies with "DHCP Offer" but
> that offer never reaches wireless client.
Do you have WDS enabled? If not, DHCP has issues in that scenario:

Aaron Z