Two Subnets On WAN Port?

Painted_Turtle Posts: 2
First Anniversary First Comment Zyxel Certified Network Administrator - WLAN Zyxel Certified Network Administrator - Switch
edited April 2021 in Security

How does one configure an ATP with two subnets on the same WAN port?

For customers wanting a static IP block, one of our ISPs (Comcast Cable) provides a cable modem/router which provides two different IP blocks to the customer. One is the public, static, block and the other is a private, block. Typically the private block is DHCP served.

For example, they might give you the following configuration for your public IP if you wanted one public IP: Public IP for your use The public IP of the cable modem/router Subnet Mask

On the same interface port, they would also provide a NATed private block, which is typically something like: cable modem/router Range of private IP available for use Subnet Mask

And typically, there is a range of addresses which are DHCP served from this block.

Since they do provide a customer login to their box, and since there is some useful monitoring and troubleshooting information that can be gleaned from it, it is desirable to be able to also connect to the cable box.


  1. How does one configure an ZyXEL ATP to support this?
  2. Is there any kind of standard name for this type of configuration?

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