I dont know how make it over openwrt configs (i dont use these config files), But is it possible to do it with swconfig. You can make vlan interface and these vlans make tagged to cpu port and untagged to switchport. Then you can rename it with iproute to eth1, eth2 .....
im using this way on huge of rb750.
Example working for me
swconfig dev sw0 set enable_vlan 1
vconfig add sw0 2
swconfig dev sw0 port 2 set pvid 2
swconfig dev sw0 vlan 2 set ports "0t 2"
ip link set sw0.2 name eth1
ip link set eth1 txqueuelen 1000
swconfig dev sw0 set apply
And repeat it for each port you want to separate
You Have to change sw0 with switchname of your router
swconfig list
Im not sure if tiny ip package from busybox know rename interfaces. Im using full iproute2 package.
(Last edited by milankocvara on 28 May 2015, 22:09)