Found
more info on sunsolve - note the following in that link:
The latest Solaris Ethernet devices and drivers (hme, qfe, eri, dmfe, ge, ce) are fully 802.3 compliant.
Even though these drivers have the ability to change auto-neg, speed and duplex settings,
Sun's preferred (and recommended) way is to auto-negotiate and not disable auto-neg capabilities!
In general, any commodity Level 2 Switch will work in a Solaris environment if it provides industry
standard features in the following areas of performance: Auto-Negotiation, Internal, Bandwidth, Buffering & Latency.
Note: Sun does not endorse nor recommend any particular makes or models of switches or hubs.
Always read the manufacturer's specifications to verify that a switch meets the requirements.
In some cases, auto-negotiation capabilities could be disabled on both sides of the link, e.g., for
troubleshooting, compatibility problems, or permanent link connections in order
to "lock" the speed and duplex of the Ethernet link.
Note: Both sides, the Solaris driver and switch (the "link partners"), must be set for the same capabilities.
Setting one side to auto-neg and forcing the other side will not work correctly.