Inter-Packet Gap Parameters

The PCI FastEthernet and Expansion (PFEX) ASIC and the SBus FastEthernet Parallel SCSI (FEPS) ASIC support the programmable inter-packet gap (IPG) parameters ipg1 and ipg2. The total IPG is the sum of ipg1 and ipg2. The total default IPG is 9.6 microseconds when the link speed set, by the auto-negotiation protocol, is 10 Mbps. When the link speed is 100 Mbps, the total default IPG is 0.96 microseconds.

Table 2-3 lists the default values and allowable values for the IPG parameters, ipg1 and ipg2.

Table 2-3 Read-Write Inter-Packet Gap Parameter Values and Descriptions

Parameter	Values  (Byte Time)	Description
ipg1	0, 255	ipg1 = 8 (default at initialization)
ipg2	0, 255	ipg2 = 4 (default at initialization)

By default, the driver sets ipg1 to 8-byte time and ipg2 to 4-byte time, which are the standard values. (Byte time is the time it takes to transmit one byte on the link, with a link speed of either 100 Mbps or 10 Mbps.)

If your network has systems that use a longer IPG (the sum of ipg1 and ipg2) and if those machines seem to be slow in accessing the network, increase the values of ipg1 and ipg2 to match the longer IPGs of other machines.