PPPoE and 2 Static IPs for 2 routers

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Aug 18th, 2010
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We want to connect as follows:

Internet <--> ISP PPPoE DSL Modem <--> Cisco 881 (DMVPN) <--> Cisco 871 (IPSec VPN) <--> LAN1 (Private)

                                                                 <--> LAN2 (private)

We have 1 DSL internet connection and 2 Static IP's through PPPoE and 2 unique ID's and passwords.

Currently we have the Cisco 881 with 1 IP and have an outside DMVPN connection to another location.

We want to add another Cisco 871 to inside of the 881 for a different LAN. If it can be done?

How does the PPPoE have to be setup by the ISP (Currently PPPoE providing 2IP's using 2 usernames and passwords)? No problem if the routers are set up in parallel with the DSL modem.

Can we simply define a PPPoE passthrough on the 881 so the 871 gets a public IP or do we need to apply the 2 IP's to the 881?

We are stuck on how we should approach this from a design standpoint? Details come later.

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paolo bevilacqua Thu, 08/19/2010 - 03:47
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You cannot passthrough (bridge) PPPoE from a router to another while terminating another PPPoE on the ADSL facing router. It does not work as you can see in another thread: ttps://supportforums.cisco.com/message/3160235#3160235

In other words, you are starting with a flawed design that will cause you many problems, if ever gets to work.

If there are two offices and each one want their own VPN, get two ADSL circuits.

gmatheson Thu, 08/19/2010 - 13:16
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Thank you for the well explained and definitive answer.

Saves us a lot of time looking for a solution that would not work.

Many thanks,


paolo bevilacqua Thu, 08/19/2010 - 14:37
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You are welcome, curiously the same issue came up twice today.

I must amend my answer anyway, if you connect a small switch after the ADSL modem, you might be able to terminate two PPPoE session on two different ethernet routers. However, I have not tried that myself.

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