A questin regarding SBC, T1 & Cisco Router

[riley3]

We have a question about a SBC T1 line and Cisco router. We have a customer that ordered a T1 circuit/line from SBC replacing cable from Time Warner. The Cisco router was installed along with the T1 by SBC. The router has a WAN & LAN port only. The LAN side of the router was preconfigured to 70.130.xx.xx. We can hookup to the LAN port on the router from a laptop with another 70.130.xx.xx number and get to the Internet with no problem. Late Friday we submitted DNS changes to Network Solutions to move dns from Time Warner to SBC IP numbers and it appears they worked ok. However, we can't get into the network (web sites and TS) from the outside. Ping shows all 3 outside IP numbers working (2 dns number and 1 firewall gateway (MS ISA)). We think we forgot to reboot the ISA server after reconfiguring. My question is, does Cisco routers require ports to be opened to allow outside traffic into the network or are they generally open by default when someone like SBC installs them? It seems odd that the SBC installer didn't tell the customer if that's the case. We're thinking we just need to reboot the ISA server. Sorry I don’t have any more information but can’t get into the customer’s location until Monday. Thanks, Riley

 

[KiscoKid]

Out of the box, Cisco routers don't filter IP subnets ot ports between one interface and another. You can easily make them to do that however.

Did access from the outside work BEFORE the DNS transfer? Was the external IP addressing scheme maintained, i.e. was this a just a change of E1 provider only?

If you get really stuck and the ISA server reboot doesn't resolve the issue, can you paste the current router config here please?

Thanks

 

[riley3]

Thanks very much for the quick response. I won't have access to the site until Monday AM but will post if the reboot doesn't help. The customer has been on Road Runner for the past 2 years and RR's IP numbers are 24.173.xx.xx in this area. They changed to SBC (IP numbers 70.130.xx.xx) this past week. Late Friday afternoon we changed the dns servers (they host their own) from RR IP#'s to SBC's IP#'s. Once the three IP numbers were changed on the ISA server the tech got interrupted and forgot reboot. We’re just guessing that’s the problem. It's a Win std 2003 server running only ISA 2k. We've done this often but never with a SBC putting a Cisco router in at the same time.

Later - I just found out the router is a Cisco 1721 and the SBC support tech on the phone told me it’s not installed with any ports blocked – completely open. That tells me the problem is most likely mine. Thanks again, Riley

 

[riley3]

Thanks again for the quick help. We've determined our problem is with ISA server and not the Cisco router. A setting was missed in ISA that points to the outside IP number. Still won't be able to correct it until Monday AM.
Riley