This object contains the information of a MAC change
notification event. It consists of several tuples packed
together in the format of '<tuple1><tuple2>...'.
Each tuple consist of 13 octets in the format of
'<operation><VLAN><MAC><dot1dBasePort>' where
<operation> is of size 1 octet and supports the following values
0 - End of MIB object.
1 - MAC learnt.
2 - MAC removed.
3 - MAC updated.
<VLAN> is VLAN number of the VLAN which the MAC address is
belonged to and has size of 2 octet.
<MAC> is the Layer2 Mac Address and has size of 6 octets.
<dot1dBasePort> is the value of dot1dBasePort for the
interface from which the MAC address is learnt and has size
of 4 octets.