Sun Microsystems Gigabit Ethernet MMF/UTP Adapter manual Interpacket Gap Parameters

data can be communicated. Two physical layer parameters control whether your side is the master or the slave, or whether mastership is negotiated with the link partner.

TABLE 3-7Forced Mode Parameters

ParameterDescription

master-cfg-enableDetermines whether or not during the autonegotiation process the link clock mastership is setup automatically.

master-cfg-value• If the master-cfg-enableparameter is set, then the mastership is not set up automatically but depends on the value of master-cfg-value.

•If the master-cfg-valueis set, then the physical layer expects the local device to be the link master.

•If the master-cfg-valueis not set, then the parameter expects the link partner to be the master.

•If autonegotiation is not enabled, then the value of master- cfg-enableis ignored and the value of master-cfg-valueis key to the link clock mastership.

•If the master-cfg-valueis set, then the physical layer expects the local device to be the link master.

•If the master-cfg-valueis not set, then the parameter expects the link partner to the master.

Caution – Do not adjust the link clock mastership parameters unless you clearly understand the settings of the link partner. Incorrect link clock mastership configuration results in link-up failure.

Interpacket Gap Parameters

The ipge device supports a programmable mode called enable_ipg0.

When an instance receives a packet with enable_ipg0 set (the default), The instance adds an additional time delay before transmitting the packet. This delay, set by the ipg0 parameter, is in addition to the delay set by the ipg1 and ipg2 parameters. The additional ipg0 delay helps reduce collisions.

If enable_ipg0 is disabled, the value of ipg0 is ignored and no additional delay is set. Only the delays set by ipg1 and ipg2 will be used. Disable enable_ipg0 if other systems keep sending a large number of back-to-back packets. Systems that have enable_ipg0 set might not have enough time on the network.

38 Sun PCI-Express Dual Gigabit Ethernet MMF/UTP Adapter Installation and User’s Guide • June 2006