Use ifconfig -v to see the additional values for all interfaces. Some will show more with additional verbose switches.
[2.4.4-RELEASE][root@7100.stevew.lan]/root: ifconfig -v ix0
ix0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=8400b8<VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,VLAN_HWTSO>
ether 00:08:a2:0e:a5:91
hwaddr 00:08:a2:0e:a5:91
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet autoselect
status: no carrier
plugged: SFP/SFP+/SFP28 10G Base-SR (LC)
vendor: FINISAR CORP. PN: FTLX8571D3BCV-CK SN: ANL1C1V DATE: 2012-11-21
module temperature: 34.26 C Voltage: 3.31 Volts
RX: 0.00 mW (-inf dBm) TX: 0.63 mW (-1.96 dBm)
Steve