Sporadic connectivity when wired and wireless available

[upnort]

Thinkpad T400 laptop. CentOS 7 fully updated.

I don't seem to recall this problem having existed when I first installed CentOS 7 some time back. Recently I noticed my connectivity is sporadic when both wired and wireless are available. Simple pings fail just as often as succeed.

Pulling the cable or toggling off the wireless switch resolves the problem. Just can't depend on a connection when both are available.

This seems to be a problem in Fedora 22 but not in Fedora 21. Not sure what the relationship might be.

Ideas appreciated.

[gerald_clark]

Don't have two active interfaces on the same subnet.

[upnort]

Don't have two active interfaces on the same subnet.

Why would this be a recent problem? I have never had this problem before on this laptop with Fedora 21, LMDE 1 and 2, and Slackware. Trying to understand the root cause here.

[gerald_clark]

Returned packets may not go out the same interface they came in on.
Packets going out the wrong interface may not reach the destination.

[upnort]

I understand that part. I am trying to understand why the problem exists on some (RH?) systems and not on others.