ZyXEL Communications 2WG

ZyWALL 2WG Support Notes

A20. My ZyWALL can not get an IP address from the ISP to connect to the Internet, what

can I do?

Currently, there are various ways that ISPs control their users. That is, the WAN IP is provided only when the

user is checked as an authorized user. The ISPs currently use three ways:

1. Check if the 'MAC address' is valid

2. Check if the 'Host Name' is valid, e.g., @home

If you are not able to get the Internet IP from the ISP, check which authentication method your ISP uses and

troubleshoot the problem as described below.

1. Your ISP checks the 'MAC address'

Some ISPs only provide an IP address to the user with an authorized MAC address. This authorized MAC

can be the PC's MAC which is used by the ISP for the authentication. So, if a new network card is used or

the ZyWALL is attached to the cable modem directly, the ISP will reject the DHCP discovery from this

MAC, thus no IP is assigned by the ISP.

The ZyWALL supports to clone the MAC from the first PC the ISP installed to be its WAN MAC. To

clone the MAC from the PC you need to enter that PC's IP in WAN menu of the ZyWALL web

configurator.

2. Your ISP checks the 'Host Name'

Some ISPs take advantage of the 'host name' message in a DHCP packet such as @home to do the

authentication. When first installing, the ISP's tech people configure the host name as the 'Computer Name' of

the PC in the 'Networking' settings. When the ZyWALL is attached to the cable modem to connect to the ISP,

we should configure this host name in the ZyWALL's system (menu 1).

A21. What is BOOTP/DHCP?

BOOTP stands for Bootstrap Protocol. DHCP stands for Dynamic Host Configuration Protocol. Both are

mechanisms to dynamically assign an IP address for a TCP/IP client by the server. In this case, the ZyWALL

Internet Access Sharing Router is a BOOTP/DHCP server. WinXP/2000 and WinNT clients use DHCP to

request an internal IP address, while WFW and WinSock clients use BOOTP. TCP/IP clients may specify their

own IP or utilize BOOTP/DHCP to request an IP address.

A22. What is DDNS?

The Dynamic DNS service allows you to alias a dynamic IP address to a static hostname, allowing your