Intel PCI-X, Intel Gigabit Ethernet Controllers Transmit IPG Register, Tipg 00410R/W, Rtlc, Nrtu

Register Descriptions

Field	Bit(s)	Initial	Description
		Value
			Reserved
Reserved	23	0b	Read as 0b.
			Should be written with 0b for future compatibility.
			Re-transmit on Late Collision
			When set, enables the Ethernet controller to re-transmit on a late
			collision event.
RTLC	24	0b	The collision window is speed dependent. For example, 64 bytes
			for 10/100 Mb/s and 512 bytes for 1000Mb/s operation. If a late
			collision is detected when this bit is disabled, the transmit function
			assumes the packet is successfully transmitted.
			The RTLC bit is ignored in full-duplex mode.
			No Re-transmit on underrun (82544GC/EI only)
			If this bit is set, the 82544GC/EI does not re-transmit packets that
			initially had an underrun.
NRTU1	25	0b	This function is accomplished by waiting for the entire packet to be
Reserved			buffered in the transmit FIFO before the controller attempts to re-
			transmit a packet that previously encountered an underrun. This
			operation guarantees only one underrun can occur per packet.
			This is a reserved bit for all other Ethernet controllers and should
			be written with 0b for future compatibility.
			Reserved
Reserved	31:26	0b	Read as 0.
			Should be written with 0b for future compatibility.

1.82544GC/EI only.

For the 82541xx and 82547GI/EI, carrier extension (through the TCTLCOLD field) provides a method to increase the duration of the carrier event to a minimum usable duration in order to meet a 200 m collision domain objective, even though half-duplex operation is impractical at Gigabit. Packets that are signaled from the CSMA/CD layer that do not meet the minimum slot time of 512 bytes have extension bytes appended to them in order to meet this minimum slot time requirement. The extension bytes are defined within the context of the frame encapsulation discussion of the 802.3z standard and are recognized by 802.3z compliant devices. Refer to Figure 13-1

Preamble	SFD	DA	SA	T/L	Data/Pad	FCS	Extension
				Minimum Frame Size
					Slot Time
				Duration of Carrier Event

Figure 13-1. Carrier Extended Frame Format (82541xx and 82547GI/EI)

13.4.34Transmit IPG Register

TIPG (00410;R/W)

This register controls the IPG (Inter Packet Gap) timer for the Ethernet controller.

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