When your WAP acts as a gateway, it forwards traffic between two subnets (your wireless network and the wired network).
For TCP/IP, this means that the wireless TCP/IP clients can't directly reach the wired TCP/IP clients without first sending their packets to the gateway (your WAP). Your WAP network interfaces will also each be assigned an IP address.
This type of configuration is common for SOHO (small office, home office) or home use, where the WAP is directly connected to your Internet service provider. Using this type of configuration lets you:
The TCP/IP configuration of a gateway and firewall is the same whether your network interfaces are wired or wireless. For details of how to configure a NAT, visit http://www.netbsd.org/docs/.
Once your network is active, you will assign each interface of your WAP an IP address, enable forwarding of IP packets between interfaces, and apply the appropriate firewall and NAT configuration. For more information, see “DHCP server on WAP acting as a gateway” in the section on TCP/IP interface configuration.