Will existing Cisco 2621 work with BT infinity

[gemnetitservices]

We have an exisiting Cisco 2621 XM router with an ADSL interface connected to BT Broadband.  Basic layout below:

Internet------ADSL on Cisco 2621 ------ Pix 506e ---- 3600 switch with interVLAN routing to multiple VLANS

There are 5 static IP addresses.  The internal FE port on the 2621 has one external assigned to it.  The outside int of the PIX has another external IP assigned from the 5.  The other 3 are NATd through to internal IPs via the PIX to inernal servers etc.

The ADSL is being upgraded to BT Infinity.  This new service comes with a separate VDSL modem and a separate BT router.  Ideally I want to ignore the BT router and use the Cisco 2621 as it has 2 FE ports and I suspect I could do something using PPPOE. 

So New layout would look like

Internet ----- BT VDSL modem------ Cisco 2621 ----- Pix 506e ---- 3600 switch with interVLAN routing to multiple VLANS

I think it is a bit strange the way it is setup as 2 static IPs cant be used.  There is an opportunity to use a ASA 5505 which may become available...

Has anyone done something similar?  Any help much appriciated

[o.wong]

Hi Gerald,

I would ditch the 2621 router - I can't see any reason for it to be there.

The BT Infinity service is PPPoE - therefore, if you can connect a PPPoE client directly into the BT VDSL modem, you should be able to bring up the connection.  There's a PIX configuration guide here:

http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_configuration_example09186a00801055dd.shtml

There's two reasons why you should get rid of the 2621:

- it's old, and no longer supported by Cisco (this applies to the PIX-506E also - if you can get the ASA, so much the better)

- in all likelihood, the 2621 would be a bandwidth bottleneck on a BT Infinity service.  (2621 router is rated at 12,500 packets per second - based on 64 byte packets, that's only 12.8Mbps)

Your setup would look like this:

Internet ------- BT VDSL modem --[PPPoE]--- PIX/ASA ------ multilayer switch

This will also use less of your static IPs, as there is now no router in the way.

Of course, if the router is performing any function other than just ADSL termination, then this is null and void.

Hope this helps.