Example for built in ce0 interface
#kstat -p
note what are the interface and parameter of interest
e.g. to see only ce0 link_speed, link_up and link_duplex parameters
# kstat -p 'ce:0::/link_(speed|up|duplex)/'
sample output :
ce:0:ce0:link_duplex 1
ce:0:ce0:link_speed 100
ce:0:ce0:link_up 1
e.g. to see eri0 ifspeed, link_up, link_duplex parameters
# kstat -p 'eri:0::/(ifspeed|link_up|link_speed)/'