Allow externial IP address to pass through 678 ROuter

[Swoop]

Okay here is my deal, any help would be greatly appreciated. We currently have 10 workstations behind our Cisco 678 Router. The router is acting as DHCP server and also performs NAT/PAT.

We are currently in the process of setting up a Microsoft ISA Server Firewall to sit between our Cisco and our workstations. The ISA Server will be performing NAT and DHCP to the internal workstations.

What I want to do is be able to pass the external IP address we receive from our ISP through the Cisco and directly to the external interface on the ISA server. Basically I want to disable NAT/PAt and DHCP on the Cisco. The Cisco will hook directly to the external interface of the ISA server. I just want my Cisco to act as a DSL modem. Can this be done?

Thanks


Charles

[Siliconjunkie]

Why not just static nat the external IP of the 678 to the internal IP of the ISA box. Then you can still write acls if need be.

I doubt you are going to be able to do what you want with only one IP.

[davidw]

Yeah, ACLs are the way to go on this one.

[Swoop]

Couple of things, one, what do you mean by ACL's and two, when you say static nat the external IP of the 678 to the ISA box IP are you talking about using the "set nat entry add" command in the router?

BTW, I found out from my ISP that we currently have a PPPOA DSL connection and that if we wanted to put the 678 in bridging mode then we would have to switch over to a PPPOE connection, and that just brings up a whole new set of problems when trying to run ISA on a PPPOE connection.

Thanks,

Charles