  Due to the rapid development of IoT technology, automatic guided vehicles
(AGVs) interact with an industrial control system (ICS) through the wireless
network to support the freight distribution in the automated warehouse.
However, the message exchange among AGVs and the ICS would experience large
packet loss or long transmission delay, in the presence of wireless network
link failure and link congestion. Therefore, the performance of warehouse
automation would be degraded. In this paper, we propose the Software Defined
Fast Failure Recovery(SD-FFR) mechanism, aiming to improve network reliability
and avoid link congestion caused by load unbalance. With SD-FFR, when link
failure occurs, the SDN controller actively detects the link failure within
milliseconds, and then reroutes the affected traffic flows accordingly. The
proposed SD-FFR mechanism also takes load balance into consideration in
selecting routing paths when a new traffic flow joins or link failure occurs in
the network. The evaluation results show that network performance can be time
efficiently improved.
