Algorithm 1 Add to a slot

Require: a hash table with N slots, $hash\_table$; each slot contains three fields: $ip$, $mac$, $counter$; an array with k random numbers, $rand$; the length of a bucket, $row\_length$; the threshold, T;

1: procedure ADD-A-SLOT($src\_ip$, $dst\_mac$)

2:  $now\_column, empty\_flag, empty\_index, find\_flag, hash\_value\leftarrow 0$

3:  $insert\_slot\leftarrow \left\{ip: src\_ip, mac: dst\_mac, counter: 1\right\}$

4:  for $i = 1$ to k do

5:    $hash\_value\leftarrow hash(src\_ip, dst\_mac, rand\left[i\right])$

6:    $now\_index\leftarrow now\_column\ast row\_length+hash\_value$

7:    $now\_column\leftarrow now\_column+1$

8:    $read\_slot\leftarrow read\_hash\_table(now\_index)$

9:    if $empty\_flag=0$ and $read\_slot.counter=0$ then

10:       $empty\_flag\leftarrow 1$

11:       $empty\_index\leftarrow now\_index$

12:    else if $read\_slot.ip=src\_ip$ and $read\_slot.mac=dst\_mac$ then

13:       $insert\_slot.counter\leftarrow read\_slot.counter+1$

14:       if $insert\_slot.counter\ge T$ then

15:         $alert\_to\_controller(dst\_mac)$

16:         $insert\_slot\leftarrow \left\{ip: 0, mac:0, counter: 0\right\}$

17:       end if

18:       $write\_hash\_table(now\_index, insert\_slot)$

19:       $find\_flag\leftarrow 1$

20:    end if

21:  end for

22:  if $find\_flag=0$ and $empty\_flag=1$ then

23:    $write\_hash\_table(empty\_index, insert\_slot)$

24:  end if

25: end procedure