ZyXEL Communications ZyXEL Vantage VSG-1000 - Manual (Page 107)

VSG-1000 Vantage Service Gateway
IP Address Assignment Conflicts A
Appendix A
IP Address Assignment Conflicts
This appendix describes situations where IP address conflicts may occur. Subscribers with duplicate IP addresses
will not be able to access the Internet.
Case A: The VSG is using the same LAN and WAN IP addresses
The following figure shows an example where the VSG is using a WAN IP address that is the same as the IP
address of a computer on the LAN.
Diagram 1 IP Address Conflicts: Case A
You must set the VSG to use different LAN and WAN IP addresses on different subnets if you enable DHCP server
on the VSG. For example, you set the WAN IP address to 192.59.1.1 and the LAN IP address to 10.59.1.1.
Otherwise, It is recommended the VSG use a public WAN IP address.
Case B: The VSG LAN IP address conflicts with the DHCP client IP address
In the following figure, the VSG is acting as a DHCP server. The VSG assigns an IP address, which is the same as
its LAN port IP address, to a DHCP client attached to the LAN.
Diagram 2 IP Address Conflicts: Case B
To solve this problem, make sure the VSG LAN IP address is not in the DHCP IP address pool.
Case C: The Subscriber IP address is the same as the IP address of a network device
The following figure depicts an example where the subscriber IP address is the same as the IP address of a network
device not attached to the VSG.
Diagram 3 IP Address Conflicts: Case C
You must set the VSG to use different LAN and WAN IP addresses on different subnets if you enable DHCP server
on the VSG. For example, you set the WAN IP address to 192.59.1.1 and the LAN IP address to 10.59.1.1.
Otherwise, It is recommended the VSG use a public WAN IP address.