Data Sheet

Programming Interface — Ethernet Controller I210

489

8.18.11 Defer Count - DC (0x4030; RC)

This register counts defer events. A defer event occurs when the transmitter cannot immediately send

a packet due to the medium being busy either because another device is transmitting, the IPG timer

has not expired, half-duplex deferral events, reception of XOFF frames, or the link is not up. This

streaming transmits that are deferred due to TX IPG.

8.18.12 Transmit with No CRS - TNCRS (0x4034; RC)

This register counts the number of successful packet transmissions in which the CRS input from the PHY

was not asserted within one slot time of start of transmission from the MAC. Start of transmission is

defined as the assertion of TX_EN to the PHY.

The PHY should assert CRS during every transmission. This register only increments if transmits are

enabled (TCTL.EN is set). This register is not valid in SGMII mode, in full-duplex mode, and in 100 Mbps

half-duplex mode .

8.18.13 Host Transmit Discarded Packets by MAC Count - HTDPMC

(0x403C; RC)

This register counts the number of packets sent by the host (and not the manageability engine) that

are dropped by the MAC. This can include packets dropped because of excessive collisions or link fail

events.

8.18.14 Receive Length Error Count - RLEC (0x4040; RC)

This register counts receive length error events. A length error occurs if an incoming packet passes the

filter criteria but is undersized or oversized. Packets less than 64 bytes are undersized. Packets over

1518, 1522 or 1526 bytes (according to the number of VLAN tags present) are oversized if Long Packet

Enable (RCTL.LPE) is 0b. If LPE is 1b, then an incoming, packet is considered oversized if it exceeds the

size defined in RLPML.RLPML field.

If receives are not enabled, this register does not increment. These lengths are based on bytes in the

received packet from <Destination Address> through <CRC>, inclusive. Packets sent to the

manageability engine are included in this counter.

Note: Runt packets smaller than 25 bytes may not be counted by this counter.

Field Bit(s) Initial Value Description

CDC 31:0 0x0 Number of defer events.

Field Bit(s) Initial Value Description

TNCRS 31:0 0x0 Number of transmissions without a CRS assertion from the PHY.

Field Bit(s) Initial Value Description

HTDPMC 31:0 0x0 Number of packets sent by the host but discarded by the MAC.