Actually you can write a litle bash script to get all the informations you require:

all the commands below, just assemble them to do anything you need:

#To find which driver, interfaces you have:
<ifconfig -a>

Here are some NIC drivers userd by Solaris (just in case)
# hme - Sun Fast-Ethernet device driver
# qfe - Sun qfe Quad Fast-Ethernet device driver
# eri - Fast-Ethernet device driver
# fjqe - Fujitsu PCI Quad 10/100 Ethernet
# fjgi - Fujitsu PCI Gigabit Ethernet
# e1000g - Gigabit Ethernet driver Intel PRO/1000
# bge - Gigabit Ethernet driver for Broadcom BCM57xx
# nxge - Sun 10/1 Gigabit Ethernet network driver
# ce - Cassini Gigabit-Ethernet device driver

#Check the which instance of NIC port we are connecting to:

ndd -get /dev/interface instance

#Check status:
ndd -get /dev/interface link_status (0=down, 1=up)

#Check link mode:
ndd -get /dev/interface link_mode (0=half-duplex, 1=full-duplex)

#Check link speed :
ndd -get /dev/interface link_speed (0=10mbs, 1=100mbs)

#Check autonegotiation capabilities:
ndd -get /dev/interface adv_autoneg_cap (0=false, 1=true)

#Set autonegotiation:
ndd -set /dev/intergace adv_autoneg_cap 1 (set to true)

#Finding errors in dmesg
grep -i <interface> /var/adm/messages

Note: Those changes written with ndd -set, are not persisten, they will be lost at system reboot. But if you like to add them permanently, you may consider editing file /kernel/drv/<interface>.conf


Hope this helped
______________________
The power of Solaris cannot be experienced on an Intel machine!!!