- Sun Installation and User's Guide GigaSwift Ethernet Adapter

Chapter 4 Configuring Driver Parameters 41
Gigabit Link Clock Mastership Controls
The concept of link clock mastership was introduced with gigabit twisted-pair
technology. One side of the link is the master that provides the link clock and the
other side is the slave that uses the link clock. Once this relationship is established,
the link is up, and 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 describes the Forced mode parameters.
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 ce device supports a programmable mode called enable_ipg0.
When an instance receives a packet with enable_ipg0 set (the default), it 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.
TABLE 4-4 Forced Mode Parameters
Parameter Description
master-cfg-enable Determines whether or not during the autonegotiation process
the link clock mastership is setup automatically.
master-cfg-value • If the master-cfg-enable parameter is set, then the
mastership is not set up automatically but depends on the
value of master-cfg-value.
• If the master-cfg-value is set then the physical layer
expects the local device to be the link master.
• If the master-cfg-value is not set then the parameter
expects the link partner to be the master.
• If autonegotiation is not enabled, then the value of master-
cfg-enable is ignored and the value of master-cfg-value
is key to the link clock mastership.
• If the master-cfg-value is set, then the physical layer
expects the local device to be the link master.
• If the master-cfg-value is not set then the parameter
expects the link partner to the master.