Portal authentication modes

Portal authentication has three modes: direct authentication, re-DHCP authentication, and cross-subnet authentication. In direct authentication and re-DHCP authentication, no Layer 3 forwarding devices exist between the authentication client and the access device. In cross-subnet authentication, Layer 3 forwarding devices can exist between the authentication client and the access device.

A user manually configures a public IP address or obtains a public IP address through DHCP. Before authentication, the user can access only the portal Web server and predefined authentication-free websites. After passing authentication, the user can access other network resources. The process of direct authentication is simpler than that of re-DHCP authentication.

Before a user passes authentication, DHCP allocates an IP address (a private IP address) to the user. The user can access only the portal Web server and predefined authentication-free websites. After the user passes authentication, DHCP reallocates an IP address (a public IP address) to the user. The user then can access other network resources. No public IP address is allocated to users who fail authentication. Re-DHCP authentication saves public IP addresses. For example, an ISP can allocate public IP addresses to broadband users only when they access networks beyond the residential community network.

Only the HPE iNode client supports re-DHCP authentication. IPv6 portal authentication does not support the re-DHCP authentication mode.

Cross-subnet authentication is similar to direct authentication, except it allows Layer 3 forwarding devices to exist between the authentication client and the access device.

In direct authentication, re-DHCP authentication, and cross-subnet authentication, a user's IP address uniquely identifies the user. After a user passes authentication, the access device generates an ACL for the user based on the user's IP address to control forwarding of the packets from the user. Because no Layer 3 forwarding device exists between authentication clients and the access device in direct authentication and re-DHCP authentication, the access device can learn the user MAC addresses. The access device can enhance its capability of controlling packet forwarding by using the learned MAC addresses.