[U-Boot] packet dropping problem in uboot

Dear All, I have a board with a DSP processor and two Ethernet controllers(dm9000) . U-boot is installed on the DSP processor which is configured to work with these two Ethernets. I have two questions: 1- I can just work with one of the Ethernets at a time and call eth_rx for it, is it possible to work with both of ethernets and read data from them as data arrives(currently I have implemented a polling mechanism to read from both eths)? 2- I want to read packets from one eth and send it from another eth, but I found out that I can just transfer ARP packets in this way and I can't even read other packet types like UDP, Does uboot have a built-in mechanism for dropping and filtering some kind of packets?

Regards, Ahari