This bug is to track the fact that l2switch will not operate against a switch that has already connected to openflowplugin when l2switch is started.

this is easy to see with these steps:

1. install odl-openflowplugin-flow-services-ui
2. attach openflow devices (e.g. start mininet)
3. install odl-l2switch-switch-ui

what I understand to be happening is that because 2 happens before 3
above, l2switch does not recognize the switches and does not push
the flows to learn links or hosts

Being able to start l2switch in a live network should be supported.

Maybe a more reasonable way to illustrate this problem is in a larger
network:

1. start mininet in a tree topo with depth=8 (255 switches)
2. start controller and install the one feature odl-l2switch-switch-ui

as l2switch is dependent on openflowplugin, those services will be coming
up first. The network is active and attempting to connect to the controller.
there will be a period between when openflowplugin is up and accepting
openflow connections and when l2switch is ready to process these events.
For any of the switches that connect in this window, they would not get
the proper flows to allow l2switch to operate.

In one test like this, after the controller finished starting all services,
the overall link count was 495 instead of 508. Restarting mininet in this
case will make things fine. Restarting a real network of this size is probably
not ok.

there may be some workarounds, but it seems a reasonable request that l2switch
can handle devices existing as well as newly connecting when it's activated.
another point to make is that it may eventually take longer between when
openflowplugin is ready and l2switch is ready. The longer that takes the more
pronounced this would be.