ethtool showing link detected when no link present
I have an SFP ethernet interface which ethtool shows as having a link detected = yes, when there isn't actually any cable present - see output below:
Settings for eth6:
Supported ports: [ FIBRE ]
Supported link modes: 1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 1000baseT/Full
Advertised auto-negotiation: Yes
Supports Wake-on: umbg
Current message level: 0x00000007 (7)
Link detected: yes
Now, the problem is consistent between reboots. I can correct the problem by doing an ifconfig down and then ifconfig up, but this this doesn't sit easy with me. I'd like to find out why the issue occurs in the first place as I think it may be related to an issue where I saw all 16 interfaces fail to come up with the exception of just eth6, the interface I'm experiencing the problem on! The issue occurs regardless of whether there is a fibre transceiver inserted. Furthermore, the issue occurs on multiple identical machines I'm running on, again all consistently showing the problem.
The only hint I currently have on the problem is the following line in syslog:
e1000: eth6: e1000_watchdog_task: NIC Link is Up 1000 Mbps Full Duplex
and there's no other occurrence of this line for any other interface in the syslog.
lspci shows the driver to be:
07:00.0 Ethernet controller: Intel Corporation 82571EB Gigabit Ethernet Controller (rev 06)
And I'm running kernel 2.6.17
Any light is greatly appreciated!