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Using my own router with a block of static IP addresses


Using my own router with a block of static IP addresses


I have just had business fiber installed and am leasing a /27 block of IP addresses.  I have a BGW210 modem.

I'd like to use my own IP router with my static block of IP addresses -- the /27 means I have 30 useable addresses.

I can't figure out how to configure the BGW210 though to do this.  Any suggestions?


It has pass-through, public subnet, and cascade router.  I've tried each approach and spent 6-7 hours on the phone with the offshore tech support people.  No offense, but they don't seem to understand the problem.

Any suggestions?


I want the modem to pass all traffic for my /27 block to my own router which is connected to the LAN port.





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Accepted by drbobbyk
‎11-03-2017 7:18 PM

Re: Using my own router with a block of static IP addresses


I think I figured it out.

On my modem, first, I turn off all firewall rules, packet filters, etc.


Then, I go configure cascade router.  I assign the external interface of my router an private-ip address outside the dhcp pool assigned by the modem but in the network. for example.  The modem's internal address is


Then, for cascade router, I tell the modem that my cascade router is and the netblock to forward to my router is the block that AT&T assigned me.  For example, my block is x.x.x.128/27  or x.x.x.128 and for the netmask.

On my router, on the internal interface, I assign it the net block x.x.x.128/27 and use the first address in the block for my router's interface on my subnet.  Rest of addresses are assigned either statically or via dhcp.  It seems to work and it doesnt waste one of my routable addresses on my router's external interface.


I can't be the only putz doing this.  I wish the tech support people overseas would have told me this.



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