The Cisco DPC3939B and VPNs

Question

We just had a DPC3939B installed. We have a requirement to have a VPN connection to another site but I can find no information about how that is done.  We currently have a Barracuda Link Balancer with another internet connection that we currently use for the VPN but we want to get off that internet connection. Our new DPC3939B is plugged into the second in port on the Barracuda. Obviously I need to get the external IP routed to the Barracuda to use the VPN functionality. What is the best way to handle it? Is it even possible?

Frank · Accepted Answer

Thanks for responding VBSSP-RICH

We have a block of 5 static IP's. We will be using 2 for VPN's.

We currently have static external IP's assigned to the Barracuda. Obviously we cannot do that with the DPC3939B because it's a gateway and not just a cable-modem. I an having a hard time finding out if it will passthrough all the VPN protocols if I use NAT. Or, if there is another way of setting this up. I heard talk about a "True Bridge Mode" but I would lose some functionality that we want to keep.

VBSSP-RICH · Answer

Hello Frank and welcome,

You should be able to implement and use your Barracuda Link Balancer (BLB) device for your VPN as long as the configuration setup is established correctly (as partially indicated within here ). If you could let us know if your BLB is using Comcast Gateway (CG) DHCP or StaticIP, that would be helpful for us to provide additional input assistance for you. The best way to mplement this is to obtain a staticIP from Comcast to make sure the IP address of the BLB is constantly accessible for the obious reasons.

Hope this helps you out.

VBSSP-RICH · Answer

Hey Frank,

That's good news that you are using StaticIPs for this standard VPN networkiing practice. The standard VPN ports should automatically be opened for this facility but you can always log into the DPC by connecting a computer to any one of the LanPorts 104 in the rear, bring up a browser, username=cusadmin, pw=highspeed and be able to use the advanced StaticIP Port Forwards to insure a port on a staticIP device is definitively open both TCP & UDP. You cannot use True Bridge Mode on any Comcast Gateway with StaticIP, so this is not an option. You have all the facilities you need for many other VPN customer are successfully implementing this facility.

Hope this helps you out and keep us posted on your progresss.