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Configuring Static IP Block - Need Help!

Configuring Static IP Block - Need Help!

I've been reading and hacking at this for about 3 days now and still haven't gotten any of my static IP's working. First of all let me explain my setup...


I have U-verse with a Motorola NVG589 Modem/Router. The Motorola is being used as the modem and is setup in IP Passthrough mode so that my Cisco router can do all of the routing. The Cisco has Tomato firmware on it. All this functions perfectly.


I have been given my IP block: XXX.XXX.XXX.104/8 (this is clearly not a /8, its a /29 and ATT notes it in their system as /8 to mean an 8 IP block)


I followed this writeup to add a Public Subnet to the modem:


That part seemed to go OK but the router did not take on the expected public address of XXX.XXX.XXX.110. It still has it's 99.XXX.XXX.241 address as it always did. I believe this is wrong.


Does anyone know if this is right or wrong? In IP passthrough mode, my Cisco router gets assigned the public IP that the Motorola obtains. I've considered setting the Cisco router's IP to the .110 address but I think the Motorola should assign it as its in pasthrough mode. 


I also noticed that no matter what, some of the devices like the TV dvr transmitter thing is getting assigned one of my public IP's which is NOT what I want...


What gateway should I be setting on my hosts with public IP's? With it set to (my Cisco) I can ping .110. 


I've set it's IP to .108 but I can't connect to it from anywhere else in my network. Traceroute provides this...


Traceroute to XXX.XXX.XXX.108 (XXX.XXX.XXX.108), 30 hops max, 60 byte packets
1 * * *
2 ( 2.086 ms 2.098 ms 2.117 ms
3 ( 3001.744 ms !H 3002.251 ms !H 3002.311 ms !H


Any help or suggestions? Please let me know if I left out any useful information...

Message 1 of 7
ACE - Master

Re: Configuring Static IP Block - Need Help!

I would recommend that you send a Private Message to the ATTU-verseCare Community Specialist team.  One of the specialists will respond to your PM shortly.  Please look for the flashing envelope at the top right of the page for your response from a team member.


In your message provide the best way and time to reach out to you.  They can help you get this all set up.

"If you find this post helpful and it solved your issue please mark it as a solution.  This will help other forum members locate it and will also let everyone know that it corrected your problem. If they have the same issue they will know how to solve theirs"

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 2 of 7

Re: Configuring Static IP Block - Need Help!

Ok I will give that a shot. I'll mark this as a solution if I can get it all working...

Message 3 of 7
Community Support

Re: Configuring Static IP Block - Need Help!

Hi phutchins82,


We have received your message and will be happy to work with you to get this resolved.


-David T

AT&T Customer Care

Need help with an account specific question?  Post a new question here on the forums by clicking the "Ask a Question" button.
For additional support, please visit us at our AT&T services hub.
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Employee Contributor*
*I am an AT&T employee and the postings on this site are my own and don't necessarily represent AT&T's position, strategies or opinions.
Message 4 of 7

Re: Configuring Static IP Block - Need Help!

I'd like to give David a huge thanks for his help! He gave me a call the other night and helped me get a lot further than I was before. I'm still not quite where I want to be with this but I have atleast got it working.


To anyone that is looking for the answer, I will write up a post on how I got to where I am. I have been able to forward traffic in and out to nodes with private IP's behind my router but have not yet found a way to assign the nodes the actual public IP's while they are behind my Cisco router set to be passthrough behind the Motorola....

Message 5 of 7
Community Manager

Re: Configuring Static IP Block - Need Help!

Awesome, thank you for letting us know!



Rethink Possible

Did a post have a solution that worked for you? Help other people find solutions faster by marking posts that helped you as an "Accepted Solution". Learn about accepted solutions: Learn More.

Employee Contributor*
*I am an AT&T employee and the postings on this site are my own and don't necessarily represent AT&T's position, strategies or opinions.
Message 6 of 7

Re: Configuring Static IP Block - Need Help!

The problem returned...


I had everything working for quite a while but a few months ago it stopped working.


I can get the modem to assign static IP's directly from it but when I have it in passthrough mode so that I can use my own router, the static IP traffic does not seem to be forwarded from ATT's router/modem to my router. My router does get the IP address of the modem/router as it is supposed to but it is not one of my static ip's like I would have expected.


Does anyone know how to get traffic forwarded to your router when the att router/modem is in passthrough mode?


I can ping the gateway for my static IP block from the computers plugged into my router. I have nat rules and masquerading set up to forward traffic destined for one of my public IP's to the appropriate internal address on my router.


Glad to provide any further info if needed...

Message 7 of 7
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