[c-nsp] special routing (vrf?) with Cisco 3825

[Horváth Szabolcs]

Hello,

We'd like to set up a special routing between remote sites.

The network looks like the following:

   <Site #1 LAN>        <Site #2 LAN>       <Site #3 LAN>
         |                    |                   |
   <  Site #1  >        <  Site #2  >       <  Site #3  >
   < CE router >        < CE router >       < CE router >
         |                    |                   |
         |                    |                   |
    /---------------------------------------------------\
    |                                                   |
    |          Service Provider's MPLS backbone         |
    |                                                   |
    \---------------------------------------------------/
                              |
                              |
                       < Central Site >
                       <   CE router  >
                              |
                       <   Firewall   >
                              |
                       < Central LAN  >


We have 4 sites over an IP VPN. All traffic is routed through the central CE router (the network is configured to "hub & spoke" mode).
Direct traffic between sites is not allowed, only through the central CE router. 

In addition, we have to pass the traffic through the "Firewall" which is going to or coming from the "Site #3".

1. So the route from site #1 to site #3 should look like: 

 Site #1 LAN ---> Site #1 CE router ---> SP network ---> Central CE router ---> Firewall ---> Central CE router ---> 
   SP network ---> Site #3 CE router ---> Site #3 LAN

2. The route from site #3 to site #2 should look like:
 
 Site #3 LAN ---> Site #3 CE router ---> SP network ---> Central CE router ---> Firewall ---> Central CE router --->
   SP network ---> Site #2 CE router ---> Site #2 LAN


The Central CE router is Cisco 3825.

Is this idea can be achieved with current Cisco technologies?
If yes, how does this technology called? I've read about VRF, it might help, but I'm not sure.
Could you please point out the main steps to configure this?

I have a few years Cisco experience, mostly with lan, but I have never ever used complex routing stuffs like this.
I just need a minimal info to start and I'll try to implement. In the first step, I'm just curious if this can be done or you know better solution to do this job.

Thanks in advance,
Szabolcs Horvath