set multiple WAN static ip from different subnets on same router firewall

Posted on 2011-10-12
Last Modified: 2012-05-12
We have an ISP that has provided us with 2 static IPs but on different subnets and 2 different gateways
Unfortunately, they're unable to provide us with IP's on the same subnet because we need to subscribe for more static ip addresses.

Basically we have 2 static IPs on the subnet which means there's only 2 usable IPs - one being our assigned IP and the other being the ISP's gateway IP

-1 static ip will be used for regular internet incoming/outgoing traffic
-the other static IP will be used for a publicly hosted website

The question is - can we setup these 2 static IP's with 2 different gateway's on the same router?
We have a Sonicwall NSA240

Also in regards to a physical connection, would a hub/switch be necessary to put in place in between the Sonicwall and the modem? or can we just have 1 network cable going from the modem to the sonicwall?


Question by:andrew_transparent
    LVL 20

    Expert Comment

    The Sonicwall can support two WAN interfaces.

    From your description it is not clear what you have. Are you saying that you have two (cable?) modems, each with one usable ip address? If so, put one on each of the two WAN ports of the NSA240, and configure it accordingly.

    If your configuation is different, please provide more details.
    LVL 1

    Author Comment

    1 ISP has provided us a subscription that has 1 modem and 2 static IPs from different subnets

    I do know that each port can support multiple WAN IP's but that means putting in a switch or hub in between the modem and firewall. plugging in 2 cables into the each port on the Sonicwall (2 ports will be taken up)

    I am wondering if it is possible of assigning 2 WAN IP addresses from different subnets on one port that connects from the modem.
    Hope that is a bit more clear.
    LVL 20

    Expert Comment

    From what you have provided, it appears you have a single ISP connection with an ip address range and a mask of, providing 2 usable ip addresses. Both would be on the same subnet, and have the same gateway, given that you have only one modem. Can you detail exactly what your ISP is telling you about this.
    LVL 1

    Accepted Solution

    Our ISP is messed up... They've just gone through changes and 'upgrades' and provided up IP addresses on the /30 subnet so yes, 2 usable IP's, one for us and the other is the ISP gateway address.
    And the other is different IP on the /30 subnet so we couldn't configure this to work from 1 fireall as it basically has 2 gateways.

    We've just given up and now just restructured our sservers using the 1 IP for all our web, email, internet, etc traffic...

    Thanks for your attention
    LVL 1

    Author Closing Comment

    I just worked around the issue...

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