VPN Tunnel Interface Support for IP Helper

The VPN Tunnel Interface can support IP Helper. DHCP Replay in IP Helper with Tunnel Interface Support shows a simple example of DHCP replay in IP Helper:

• PC is the device needed to get an IPv4 address from the DHCP protocol.
• GatewayA is the gateway-enabled IP helper.
• GatewayB is the gateway with a DHCP server.

DHCP Replay in IP Helper with Tunnel Interface Support

To configure IP Helper with a VPN Tunnel Interface

The numbers in DHCP Replay in IP Helper with Tunnel Interface support correspond to the numbered tasks.

1. In PC:
   1. Connect to the LAN (X0) subnet of GatewayA.
   2. Set to obtain an IP address through DHCP mode.
2. Set up a VPN tunnel between GatewayA and GatewayB.
   1. Add a VPN Tunnel Interface.
3. In Gateway B:
   1. Add a route entry from the Tunnel Interface’s IP address to GatewayA’s X0 interface.
   2. Add the outbound interface of the Tunnel Interface.
   3. Add an IP address range as the DHCP scope for PC.
4. In Gateway A:
   1. Enable IP Helper.
   2. Add an IP Helper DHCP relay protocol from X0 to GatewayB’s Tunnel Interface address. The protocol is DHCP.