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Connecting ISP Bridge to CPE Router

Posted on 2015-02-19
Medium Priority
Last Modified: 2016-11-23
Hello. I have an Ethernet over Copper circuit that terminates into an Adtran 838 Bridge. I have to use a Cisco router to connect the circuit into my firewall. My router (Cisco 1841) has two (2) FastEthernet (FE 0/0 & FE 0/1) Interfaces. FE 0/0 is programmed and connected to the CPE WAN IP of the Adtran Bridge. The other Interface (FE 0/1) is programmed to the gateway LAN subnet provided by the ISP, and connected to my firewall. My firewall is a Dell SonicWall NSA3500.

 I am unable to ping the gateway of the LAN subnet provided by the ISP from behind the firewall. I can ping the IP addresses of both FastEthernet interfaces from the router console. From the router console I cannot ping anything on The Internet.

I am not a Cisco expert, but, I would imagine I need the following to happen:

1.  I need the ability to ping the ISP LAN Subnet Gateway IP Address from behind my firewall.
2.  I need the ability to ping anything pingable on The Internet from the router console.

Thanks in advance for any assistance offered.
Question by:QuinnCushing
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Expert Comment

ID: 40656046
Can you ping ISP gateway from router? And a machine on the LAN?

Accepted Solution

QuinnCushing earned 0 total points
ID: 40690804
I could ping from the router to the ISP gateway. I was unable to ping the ISP gateway from the LAN.
I made a change on the firewall, to allow ICMP packets to pass from the LAN to the WAN via NAT translation.
All is working as expected now.

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