Cisco 1721 behind ADSL router - bridge needed?

[nickpin]

Hi all,

We have a 3rd party (US based) trying to set up a connection for one of our customers (UK based) but I'm not convinced about what they are telling us and would like some advice on it.

The customer has a dedicated ADSL line connecting to a Zyxel p661H ADSL router. This then has a Cisco 1721 plugged in behind it which has a VPN module. The idea is to have a VPN tunnel in place between the 3rd party (who are using some kind of Cisco access server) and the customer's 1721, so therefore the Zyxel needs to be transparent.

They've managed to get the VPN tunnel up and can access the 1721 on the customer site. However, they are saying that traffic from the customer to them is being manipulated, in that the Zyxel is adding something to the header of the packets. They tried to configure the Zyxel to act in bridge mode, but are saying that this isn't working, as the US and UK are on different standards - by this we think they mean the kit in the UK is using PPPoA and the US is using PPPoE - and therefore they want us to buy a seperate bridge to put in place.

My problem is that I don't see why a seperate bridge is needed?? Surely there must be instances of people in the UK having a 1721 setup behind an ADSL router without the need for additional hardware?

Can anyone offer advice on this?

Cheers,
Nick

 

[kbing]

Today I just setup a PPPoE PIX firewall to connect to our ISP's PPPoA connection. They don't support PPPoE but it works. Not sure if that completely relates to your problem.

Good luck.

 

[Rob057]

Nick

Had exactly the same problem as you describe last year but from the UK to US. Our final solution was to take the 3rd party modem out of the loop and fit an ADSL module to the 1700 router. We also decided to pay the ISP to supply a static IP address as we were finding that the GRE tunnel would drop and the only way we could bring it back up was to ping through the tunnel from the router. Before you all jump on me about keep alive etc it was a totally random thing that might happen once a day 10 times a day or not for a week. From our testing the main common factor was always routing and more to the point the way our ISP handled its dynamic routing.

Cheers
Rob

 

[nickpin]

Cheers for the info Rob. We're still testing and so far the US side are saying it's down to the ADSL router not routing traffic correctly, or adding something to the packet headers. I've disagreed with this - after all, if the router company made their routers send the traffic in a non-standard way they might not sell too much product...

If the latest test fails then I'm going to look at the ADSL module solution - seems like the easiest way to get it done.