2-8
AIC-6915 Ethernet LAN Controller Programmer’s Manual
Table 2-8. Receive Completion Descriptor (Word 1)
Bit(s)
Description/Function
Status2 field
31
Perfect
- destination address matches one of the 16 predefined “perfect” addresses.
30
Hash
- hashed destination address matches a bit set in the hash table
29
CRC Error
- TRUE if the packet had a CRC error. [PE-15 CRC error]
28
ISL CRC error
- TBD
27
Dribble
- TRUE if the packet contains a noninteger number of bytes (i.e. extra bits or an
extra nibble).
26
Receive Code Violation
- An illegal 4B/5B code was received in the packet.
25
Vlan Frame
- TRUE if the packet’s tag matched the tag programmed in the MAC
VlanType register.
24
ChecksumOk
- If set, the packet is a TCP or UDP packet, the checksum was checked
and is good.
23
ChecksumBad
- If set, the packet is a TCP or UDP packet, the checksum was checked
and is bad
22
PartialChecksumValid
- If set, the partial checksum is valid
21
Fragmented
- If set, the frame was fragmented
20
TcpFrame
- If set, the frame was a TCP frame
19
UdpFrame
- If set, the frame was a UDP frame
18:16
FrameType
- 0=Unknown, 1=IPv4, 2=IPv6, 3=IPX, 4=Icmp, 5=Unsupported
Status3 field
15
IslFrame
- If set, the frame is an ISL frame, meaning that the first 5 bytes of its
destination are 01:00:0C:00:00.
14
PauseFrame
- If set, the frame is a Pause MAC Control frame as defined in the IEEE
802.3x specification.
13
ControlFrame
- If set, the frame is a MAC control frame other than a pause frame as
defined in the IEEE 802.3 specification.
12
Header
- If set, the completion descriptor is for a frame header.
11
Trailer
- If set, the completion descriptor is for the remaining data in a frame whose
header was transferred.
StartIndex field
10:0
StartIndex
- Index of the first buffer used in the buffer queue. This field is only
important when both receive descriptor queues are being used.
