When a test is started, the ports get re-initialized. If Landslide is connected to a router or switch, that router or switch interface also has to be ready to receive the traffic. We have seen many cases where these other devices are not ready and therefore do not pass on the Landslide packets. What customer is seeing is just a timing issue. Without port reservation, all ports are initialized which takes longer. This longer time would give a switch / router time to recover from our ports going down and coming back up, so they probably will not see Landslide sends 3 ARP requests simultaneously without "Reserve Ports". With port reservation enabled, only the ports involved in the test are initialized. This happens much more quickly and the test probably starts sending the ARPs before the switch / router / DUT interface is ready. The solution is easy, use automation control to add a small delay. In cases of Cisco Routers the delay has been as high as 30 - 45 seconds.