ARP resolution not done from one end

[Nick Hibma]

>> We have a setup where each mobile node connects with 1 or more tinc instances (over different links) to a central node. tinc is running in switch mode. The link is chosen by setting the IP address on the active link's interface, and the central node sees this after the first packet on the link, and moves the MAC address to a different 'ethernet port' (link). This works really well, and keeps webmal sessions alive on a moving ship (VSat -> 3G -> VSat).
>> 
>> We have changed our setup and now the tunnel becomes idle for long periods of time. The problem is that the central node expires it's ARP table entry for the node. tinc is not forwarding ARP requests over the link / links. After doing 1 ping from the mobile node to the central node the ARP entry is there again as that end does forward ARP requests, and things are back to normal. The roaming node seems to initiate ARP resolution, while the central node does not.
>> 
>> Any points as to why the central tinc is not doing / able to do the ARP request?

Could it be that its because I have DirectOnly in there the roaming node knows where to send the ARP requests because it has a proper Subnet line in the central node's hosts file, but the central node does not have a Subnet statement anywhere for the roaming node?

Nick