Tue Nov 12 14:19:03 EST 2013

Weird bridging/routing problem on Belkin Share Max

OpenWRT doesn't route between eth0.0 (LAN) and wl0 on br-lan.
Disabling firewall completely doesn't change behavior.

Trying with ping:
            router -> raspi     OK
raspi    -> router              OK

tx-wlan  -> router -> raspi     raspi sees packets, sends reply, but router doesn't see replies on eth0.0
raspi    -> router -> tx-wlan   router doesn't see incoming on eth0.0

This looks like a routing issue, but in that case the packets coming
from the ethernet through the switch should at least be visable to the
router on eth0.0 (part of br-lan).  They are not.

Something is wrong with that switch.

If I change the arp entry of tx-wlan in raspi tables to mac of router,
packets come trough but cause redirect packets.

Best guess:

  The hardware switch doesn't properly learn the location of tx-wlan.

It doesn't seem to be linux bridge because the ethernet port doesn't
see the packets coming in.  Nothing gets dropped in the firewall
(iptables -L -v)

ARP packets do seem to get through since both raspi and tx-wlan can
learn each other's mac addresses.

Since I've seen other weird stuff happen with that switch, it's going
to take the final blame..

ARP stuff:
raspi sends arp request for tx-wlan, reply ok
tx-wlan sends arp request for raspi, no reply

Reason is the same: the switch still doesn't recognize the return path
for the arp reply.