Intel 820E manual Bus Topologies, Point-to-Point Interconnect, LOM/CNR Interconnect

Intel® 820E Chipset

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2.22.1.1.Bus Topologies

The LAN Connect Interface can be configured in several topologies, as follows:

•Direct point-to-point connection between the ICH2 and the LAN component

•Dual footprint (see Section 2.22.6.)

•LOM/CNR implementation

2.22.1.2.Point-to-Point Interconnect

The following are guidelines for a single-solution motherboard. Either the Intel 82562EH component, Intel 82562ET component or CNR is installed.

Figure 65. Single-Solution Interconnect

	L
	LAN_CLK
	LAN_RSTSYNC	Platform LAN
ICH2	LAN_RXD[2:0]	Connect
	LAN_TXD[2:0]	(PLC)
		IO_subsys_single_sol_interconn

Length requirements for Figure 65:

Intel 82562EH: L = 4.5 inches to 10.0 inches (Signal lines LAN_RXD[2:1] and LAN_TXD[2:1] are not connected.)

Intel 82562ET: L = 3.5 inches to 10.0 inches

CNR*: L = 3.0 inches to 9.0 inches (0.5 inch to 3.0 inches on card)

2.22.1.3.LOM/CNR Interconnect

The following guidelines enable an all-inclusive motherboard solution. This layout combines the LOM, dual footprint, and CNR solutions. The resistor pack ensures that either a CNR option or a LAN-on- motherboard option can be implemented at one time. The following figures show a model of this. The recommended trace routing lengths are shown in Table 23.

104 Design Guide