Data Sheet

Inline Functions—Ethernet Controller I210
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VP Field
The VP field indicates whether the incoming packet's type matches the VLAN Ethernet Type
programmed in the VET Register. For example, if the packet is a VLAN (802.1Q) type, it is set if the
packet type matches VET and CTRL.VME is set (VLAN mode enabled). It also indicates that VLAN has
been stripped from the 802.1Q packet. For more details, see Section 7.4.
IPCS (IPv4 Checksum), L4CS (L4 Checksum), and UDPCS (UDP Checksum)
The meaning of these bits is listed in Table 7-6:
Refer to Table 7-18 for a description of supported packet types for receive checksum offloading.
Unsupported packet types do not have the IPCS or L4CS bits set. IPv6 packets do not have the IPCS bit
set, but might have the L4CS bit set if the I210 recognized the TCP or UDP packet.
PIF
Hardware supplies the PIF field to expedite software processing of packets. Software must examine any
packet with PIF bit set to determine whether to accept the packet. If the PIF bit is clear, then the packet
is known to be destined to this station, so software does not need to look at the packet contents.
Multicast packets passing only the Multicast Vector (MTA) set the PIF bit. In addition, the following
condition causes PIF to be cleared:
• The DA of the packet is a multicast address and promiscuous multicast is set (RCTL.MPE = 1b).
• The DA of the packet is a broadcast address and accept broadcast mode is set (RCTL.BAM = 1b)
A MAC control frame forwarded to the host (RCTL.PMCF = 0b) that does not match any of the exact
filters, has the PIF bit set.
Error Field (8)
Most error information appears only when the store-bad-packet bit (RCTL.SBP) is set and a bad packet
is received. See Table 7-7 for a definition of the possible errors and their bit positions.
• RXE (bit 7) - RX Data Error
• IPE (bit 6) - IPv4 Checksum Error
• L4E (bit 5) - TCP/UDP Checksum Error
• Reserved (bit 4:0)
Table 7-6. IPCS, L4CS, and UDPCS
L4CS UDPCS IPCS Functionality
0b 0b 0b
Hardware does not provide checksum offload. Special case: Hardware does not provide UDP
checksum offload for IPV4 packet with UDP checksum = 0b
1b 0b 1b / 0b
Hardware provides IPv4 checksum offload if IPCS is active and TCP checksum is offload. A
pass/fail indication is provided in the Error field – IPE and L4E.
0b 1b 1b / 0b
Hardware provides IPv4 checksum offload if IPCS is active and UDP checksum is offload. A
pass/fail indication is provided in the Error field – IPE and L4E.
Table 7-7. RXE, IPE and L4E
7654 3 21 0
RXE IPE L4E Reserved