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Cisco 1841 PPPoA config with ASA 5505

turner20 asked
Medium Priority
Last Modified: 2012-05-06
Hi all,

At my branch office I currently have a Cisco 1841 with ADSL WIC authenticating PPPoA with the ISP, this router also contains ACL's and a point-to-point VPN tunnel to my main office.  We have been issued only one static IP address from the ISP which is assigned to the dialer interface on the 1841.

I am wanting to install a ASA 5505 in the branch office to give me greater firewall function and manage the VPN, but as the ASA 5505 only supports PPPoE and not PPPoA i was wondering if i can just use the 1841 to authenticate the PPPoA and then pass traffic thru to the ASA??   - if so would the VPN tunnel have to terminate on the 1841 still or could i assign the static IP address to the outside interface of the ASA?  My ISP will not give me a second IP.

Any advice would be appreciated.


Watch Question

Yes you can put the ASA behind the router and leave the public IP address on the routers external interface and terminate the VPN's on the ASA.

A good option would be to have some basic filtering on the router such as denying RFC1918 addresses (10.x.x.x, 172.16.x.x etc) then have more granular rules on the ASA

If you're NAT'ing on the router you'll need to configure VPN pass through so that VPN traffic is not NAT'd and sent straight to the ASA.

See the following link for config options


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