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3 1751's - 2 can't see or ping internet connection

This is a brand-new network, there is only one laptop at each site for setup and troubleshooting. The configuration is this:

All routers are 1751s.

Central Office: 3 serial cards

1 goes to Office 1 over a full T1, PPP, Private address at each end ( and,

1 goes to Office 2 over a full T1, PPP, Private address at each end ( and,

1 goes to ISP, fractional T1, Frame Relay, their public address. (Let's say is a public address connecting to, on their end, just to keep it simple and keep our privacy.)

Ethernet has address of on

Office 1 and Office 2 are exactly the same. Each 1751 has 1 serial card that corresponds to the serial card on the above router and they each also have a private subnet on the ethernet port. They are simply gateways to the Central Office and each other.

On the Central Office router I can ping everything, all 5 serial ports, all 3 private networks, and the internet. I have full internet connectivity here.

On Office 1 and 2 I can ping all 3 of the private networks and all the routers but both cannot ping the internet connection. They do not have any connection to the internet, either, not surprising considering I can't ping the internet connection.

Other facts: I am using NAT on the internet connection. It's set up to use that interface as the public address. I have dynamic routing set up on all routers (RIP 2.1, I think), there are no static routes entered. I've tried every combination of static routes with the same results, everything pings everything else except those two routers can't ping the internet.

Questions: Is there a special consideration in routing from private addresses to public addresses? Will RIP sort that out or do I need static routes here? Is there a conflict with routing from the two PPP connections to the Frame Relay connection? Why does dynamic routing pick up the internet connection for the Central Office private network but not the other two networks?

Any help is greatly appreciated. I've set this network up twice with the same results and I'd hate to spend so much time on what should be a simple issue.


New Member

Re: 3 1751's - 2 can't see or ping internet connection

Do you have default routes on the remote sites?

Is the RIP advertising the default routes to your remote site router?

Did you allow the remote site network to be translated?

If you do trace from the laptop at the remote site, where does it stop?

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