a question

I was not sure where to post this but I have been lurking around for a while and was not able to find an answer for this.

I recently bought an 851 series router and have been playing around with the configuration settings and have recently tried getting it to connect to the internet, I have so far been able to establish connection from the computer to the router and can even ping the ATT modem interface that I own, from the router. I unfortunately am not capable of pinging anywhere out on the internet from the 800 series router. The ATT modem is acting as the main NAT service and is not capable of switching into ethernet bridge mode so that the 851 series router can act as the main NAT service. is there something im missing here?

I'm fairly new to networking and have been studying for my CCENT for about 6 months now but this situation has thrown me for a loop. Any help would be greatly appreciated! I would like to be able to just connect the router to the internet so that when i buy more routers in the future I can set up my own internal network.

Thanks in advance.

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Comments

creamy_stew

I'm kind of drunk, so if don't make sene, just ignore me

Assuming you have other networks behind your cisco router, the ATT device won't know how to get to them. IE, it will know its own directly connected inside network on which your 851 will have an outside interface, but it wont know of any networks behind/beyond that.

If you want Internet connectivity for devices on a network behind your 851, you'll probably have to do a nat on your 851 as well.

Either that, or put a static route on the ATT device pointing the nets behind your router to your outside 851 interface. (probably wont happen)

/creamy

nevolved

Disregard what I previously wrote, I never read your post well enough:). It definitely sounds like the ATT router doesn't know how to get back into your network.

creamy_stew

nevolved:

Oh, I totally missed the fact the he couldn't even access Internet sites even from the router itself.

Weird though, one would think the ATT device would hand out dg/dns/etc in the dhcp lease.

edit:
Oh now the thread is a mess

nevolved, I actually think you had a point in that onji didn't even have Internet connectivity from the 851 itself.

edit2:
Either that or I'm outdumbing myself lol.

onji: How are you configuring the outside interface on the 851? What is your default route?

dynamik

What's your addressing scheme for your internal network? What IPs do you have assigned to the router interfaces? What's the IP of the ATT device (just say "public" if it is indeed public)? Whici devices are providing DHCP? How is your DNS setup? Can you not ping beyond the ATT device using IPs and domain names or just domain names (this would indicate a DNS issue)?

Have you power-cycled the ATT device? Sometimes that remedies odd situations like these.

kalebksp

creamy_stew wrote:

nevolved:

Oh, I totally missed the fact the he couldn't even access Internet sites even from the router itself.

Weird though, one would think the ATT device would hand out dg/dns/etc in the dhcp lease.

edit:
Oh now the thread is a mess

nevolved, I actually think you had a point in that onji didn't even have Internet connectivity from the 851 itself.

edit2:
Either that or I'm outdumbing myself lol.

onji: How are you configuring the outside interface on the 851? What is your default route?

He wouldn't have internet access from the device if it does not have the ATT modem setup as the default gateway, he'd only be able to ping the directly attached interface. I think that you are likely correct about the main issue in your first post.

onji

He wouldn't have internet access from the device if it does not have the ATT modem setup as the default gateway, he'd only be able to ping the directly attached interface. I think that you are likely correct about the main issue in your first post.

Ah, thank you! this completely fixed my problem. who knew this stuff could be so fascinating

kalebksp

Glad I could help. Good luck with your studies!