A Table Overflow LDoS Attack Defending Mechanism in Software-Defined Networks

Algorithm 1

Data collection.

(1)	Topo = Controller.topo
(2)	Ci = Topo(i).capacity
(3)	while (time elapse T)
(4)	for Si in Topo
(5)	send table_stats_request message to Si
(6)	Ai = length(table_stats_reply.active_count)
(7)	send flow_stats_request message to Si
(8)	for Fij(t) in flow_stats_reply
(9)	Dij(t) = Fij(t).duration
(10)	Pij(t) = Fij(t).packet
(11)	Bij(t) = Fij(t).byte
(12)	if timeSpan = = ilde_timeout/2 and Fij(t) is Ai,jk(t)
(13)	Ai,ik(t) = Ai,jk(t) + 1
(14)	pi(t), Pi,jk(t)//count the number of packet_in in this period