[c-nsp] router and transparent bridging help needed.

[Aaron]

I have run into a situation where i need to bridge my incoming
frame-relay t1 directly to an internal router's ethernet interface.

I have no practical experience with cisco so i'm hoping the list can
give me some pointers and suggestions and ideally i'll only get 2nd
degree burns from the flames.

The situation as i need it is as such:..
My isp has a ptp address of 1.2.3.4 and my assigned address is 1.2.3.5
(ips sanitized of course).  I want to pass the 1.2.3.5 address directly
through to my internal router eth0 interface. (sorry in adv. for the
crappy ascii art)

ISP|unknown router|serial(Frame)|address 1.2.3.4
                         |
                   ______|_______
                        wic-1t
                some cisco router
                       ethernet
                 ---------|-------------
                          |
                    1.2.3.5eth0
              internal router/firewall

I have seen some examples but honestly i'm not even sure what hardware I
should be looking at.  The example from the archives
http://marc.info/?l=cisco-nsp&m=115982463524342&w=2 was talking about a
cisco 1601, but that was a ppp based connection.

Another thread i found http://marc.info/?t=118667690000005&r=1&w=2
talked about a frame connection but then they were using a 2600 and the
replies seemed a little mixed as one guy said he should switch to ppp in
half-bridging and someone else replied about something called IRB
approach.  I'm not sure if switching to ppp is an option here so I'd
like to concentrate on frame.

I don' need/want  routing, blocking, natting at all to happen on the cisco,
essentially I want it to act like a hub/switch connected to my internal
firewall/router.

The reasoning behind this is, and please correct me if i'm wrong, I want
as simple and worry free a setup on the cisco as possible.  After
configuring it I won't be fiddling with configs unless something were to
break.  My internal router will do all the natting/firewalling and
routing, and i am confident when configuring that.  I believe the ability
on the OS is much more important than the OS.  I will not need to connect
to the cisco via tcp at all, all connects will be via the management
console.

Any suggestions on hardware (less expensive the better), IOS version
i'll need and probably most importantly, config suggestions, example or
link to pertinent material(i'm willing to learn to fish) would be most
appreciated.

Thanks in advance.

Aaron