odhcp isn't able to start correctly when lan is in vlan filtering bridge

[tiagogaspar8]

Hi all,

I have several routers configured with a single bridge and vlan filtering.

When the LAN interface is configured in one of the vlans of the bridge, odhcp starts but doesn't respond to dhcp solicitations nor sends router advertisements.

After boot, restarting odhcpd fixes the issue.

Also, if in the lan settings if I disable the "Force Link" box, odhcpd starts correctly.

Anything you need let me know, this should be easy to reproduce.

Thanks.

[systemcrash]

This seems to be a case of odhcpd responding to a 'renew' event since bridges are the devices that send those when their topology changes (e.g. via VLAN addition). Renew is typically handled by the proto script handlers. Look for 'renew=1' or something like that.

I don't see any setting which is cause or effect here, like force_link - which doesn't exist in odhcpd - meaning that the system topology probably changes just after the daemon starts, so a manual restart, or that the (static?) proto handler does a renew also for odhcpd daemon (i.e. restart) then that seems like it should happen in the scripts in openwrt repo.

[tiagogaspar8]

Yeah, I'm assuming that's the case, as for a fix, that well beyond my knowledge, could it be that odhcpd tries to bind to the bridge IP that's not yet set up and fails silently?

[systemcrash]

I think odhcpd takes those link address changes into account. So the root fix is probably those proto scripts.

Try adding something to the proto script for your lan interface and see how that works:

...
proto_xxx_renew() {
	local interface="$1"
...
	service odhcpd restart
}