Red Hat Bugzilla – Bug 474393
[RHEL4.6] ethtool/mii-tool returns wrong values about link status
Last modified: 2010-10-23 02:20:13 EDT
Description of problem:
Both ethtool and mii-tool returns wrong values about link status when the
interface is down (ifconfig ethX down).
The problem is that there is no reliable tool which would report physical
state on network cards regardless if they are up or down.
Steps to Reproduce:
1. Put the interface down (ifconfig ethX down)
2. Try to check if the link is detected or not.
this is working as designed. when an interface is downed we shut off the hardware. It doesn't make sense to keep hardware running just so it can support the reading of state information that is only relevant if the device were powered on. If you really want to determine link state when the device is on:
ifconfig ethX up; ethtool ethX; ifconfig ethX down