(Optional) Configuring the NetEngine 8000 F to Log Out an Online User and Deny Access of a New User After Detecting an IPv6 Address Conflict

To implement authentication, authorization, and accounting for users separately, users must use different IPv6 addresses to go online. This requires the NetEngine 8000 F to detect whether the IPv6 address assigned to a new user conflicts with that of an online user. By default, if the NetEngine 8000 F detects that the IPv6 address assigned to a new user is the same as the IPv6 address of an online user, it sends a DHCPv6 Decline message to the DHCPv6 server. Then the new user cannot go online, but the online user is not affected.

In scenarios in which IPv6 addresses are assigned based on the Option 82 field that carries physical location information of users and ARP probe is not configured, the online user is required to go offline to allow the new user to go online. For example, if a CPE is replaced, users attached to the old CPE will switch to the new CPE to go online. As their physical location information remains the same, they will be assigned the same IPv6 addresses as before. However, if the previous IPv6 address lease has not expired, the user information is retained. Therefore, the NetEngine 8000 F considers that the users are already online and discards the user packets sent from the new CPE. Subsequently, the users fail to go online through the new CPE. To allow the users to go online through the new CPE, configure the NetEngine 8000 F to delete the previous user information and deny new user access so that the users can be triggered to go online again.