+# del-bridge.<node_id>: Delete the bridge on node <node_id>.
+#
+# We can do this only if the db on node <node_id> is running, but
+# we don't need to re-delete if the db is restarted (hence the
+# order-only dependency).
+#
+# Deleting a bridge also deletes all interfaces of the bridge
+# as a side effect. This in turn invalidates local tunnel
+# port numbers and endpoint info on both sides of each affected tunnel.
+# The corresponding links obviously go down.
+# Controller information is also lost.
+# We invalidate the cache accordingly.