RTL8181 Wireless LAN Access Point/Gateway Controller DATA ...

RTL81810 22 OWC Out of Window Collision. A status bit. Out of window collision, Whenset, it means an “out-of-window” collision is encountered duringtransmitting packet.0 21 LNKF Link Failure. A status bit. NIC sets this bit to inform link failure todriver0 20 EXC Excessive Collision. When set, indicates that the transmission wasaborted owing to consecutive 16 collisions.0 19-16 CC3-0 Collision Counter. When Own bit =0, it’s a status field, A 4-bitcollision counter, shows the total collision times before the packet wastransmitted.0 23-16 - Reserved.0 15-0 Frame_Le Transmit frame length. This field indicates the length in TX buffer, inngth byte, to be transmitted4 31-18 RSEV Reserved.4 17-16 TAGC VLAN tag control bits:00: Packet remains unchanged when transmitting.10: Add TAG. 0x8100 (Ethernet encoded tag protocol ID, indicatingthat this is an IEEE 802.1Q VLAN packet) is inserted after sourceaddress, and 2 bytes are inserted after tag protocol ID fromVLAN_TAG field in transmit descriptor.4 15-0 VLAN_TAGThe 2-byte VLAN_TAG contains information, from upper layer, ofuser priority, canonical format indicator, and VLAN ID. Please refer toIEEE 802.1Q for detailed VLAN tag information.8 31-0 TxBuff Logic Address of transmission buffer.Reception DescriptorRx Command Descriptor (OWN=1)31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0OWN=1EORRESVRESVTAVABuffer_SizeOffset 0VLAN_TAG Offset 4RX_BUFFER_ADDRESSDummyOffset 8Offset 12Bye Bit# Bit Name DescriptionOffset#0 31 OWN When set, indicates that the descriptor is owned by NIC, and isready to receive packet. The OWN bit is set by driver afterhaving pre-allocated buffer at initialization, or the host hasreleased the buffer to driver. In this case, OWN=1.0 30 EOR End of Rx descriptor Ring. Set to 1 indicates that this descriptoris the last descriptor of Rx descriptor ring. Once NIC’s internalreceive descriptor pointer reaches here, it will return to the firstdescriptor of Rx descriptor ring after this descriptor is used bypacket reception.28CONFIDENTIAL v1.0