dmz with 2 isp's how?

[Suresh Kumar R <listuser@yahoo.com>]

Hello,

We are using LRP with eiger+extended scripts of materhorn ver 1.0 in our lrp box with 3 NICs as shown below.


      External Network (BAD) [via cisco router and rad modem ....]
                |
                |
            eth0|
         ---------------
         |203.200.144.163|             Server Network (DMZ)
         |               |eth2
         |               |----------------------------------------------
         |               |203.200.144.169|             |              |
         |               |               |             |              |
         |192.168.100.250|               |             |              |
         ---------------             --------       -------        -------
                | eth1               | SMTP |       | DNS |        | WWW |
                |                    --------       -------        -------
                |                203.200.144.170 .... (public ips)
                |
        Internal Network (GOOD)

The above setup has been working fine for one year now and now we have one more isp with a different ip subnet altogetheri, coming to the same cisco router thru another wan card. The cisco router has only one ethernet interface which goes to the lrp box.

What we need is this: we cannot change the dmz or internal lan. The traffic should go thru either of these links as which one is relatively free. 

What we tried: We added an alias for eth2 interface which shows up in the command "ip route show". But we fail to ping anywhere from the lrp box. Not even the router's new ip by the new isp.

We know the link is fine asi,  if we bypass the firewall everything is OK. 

Any suggestions on how I can survive?

With thanks,

Suresh
PS. Kindly sent a cc to suresh@ece.cet.ac.in
__________________________________________________
Suresh Kumar.R,  
Dept of Electronics & Communication
College of Engineering, Trivandrum - 695 016, INDIA
Phone: (O) 91 471 595634, 515660