Tried that just now, but...
...still no dice. However, since then, I've noticed some interesting other behavior...
I tried setting the LB's "checkinterval" value to 30, so that it checks to see if it can access nodes 30 seconds apart. (Or a "tick" in old MUD parlance). At this current point, the loopback interface on every node is down.
Then I fire up ldirectord, and let it see the nodes. (If the loopback alias on the nodes is currently up, then it won't get a response from the nodes, and will flag those nodes as unavailable.)
If I were to hit the Virtual IP from a web browser it'll time out.
However, if I turn on the loopback aliases on the nodes right now, everything works perfectly - the requests successfully route to a random node.
At least, until the next tick, maximum 30 seconds later, at which point, the load balancer cannot make a request of the node and marks it as being nonfunctional.
It is almost as if the Load Balancer does forward packets to the node, but cannot receive confirmation that it has done so. ldirectord marks the node disabled after "checkinteraval" seconds have passed, because requests to the node don't come back. It is obvious that the node is listening, but is unable to respond to the LB because the node's loopback alias is set to the Virtual IP.
Any help would be appreciated.
(From a loopback standpoint, I don't understand how a node is ever expected to communicate with another server when the node loopback alias is set to be the same as that other server.)