James Harper wrote:

Just what it says. 802.1P just assigns a vague meaning to the priority field bits, it doesn't say what you should do with them in terms if 'sticking them' in the packet. 802.1Q (vlan trunking) includes 3 bits to stick the priority field into.

http://en.wikipedia.org/wiki/802.1q is a good high level overview of what is required.

Thanks. I see.

NDIS_NET_BUFFER_LIST_8021Q_INFO contains info about 802.1Q, i need to insert 802.1Q tag in the frame before transmitting it to the backend, then strips the tag after receiving those packets. I will add those process and have a test.