The current operational practice in an IPv4 environment is to somehow keep track of which machine is using which IPv4 address at a certain point in time either by statically allocating IPv4 addresses or by using DHCP and keeping lease logs. It is also very common to identify machines in the enterprise network management systems by their MAC addresses. It is thus crucial for the secure and efficient operation of IPv4 networks to log the IP address, MAC address and L2 port combinations. There are also some tools, implemented in L2 switches, to prevent DHCP abuse and ARP poisoning called DHCP snooping and ARP inspection respectively. Let’s see what is possible in IPv6, and what countermeasures are possible to prevent abuse. There are different possible ways to assign IPv6 addresses as described in the following sections.