I have situation that causes me problems which i am not sure how to solve.
In the picture below you can see topology of network which i am dealing with. My problem is that i would like to accomplish that institution which have it's own core router and one which is just access point client, can go on internet with redudancy... In other words, their's primary route to go to internet is in up direction towards proxy server squid, and when that line is not working, their's adsl line tak over connection to internet.
So, the computers that are on LAN in that institution have in their browsers typed in proxy (exactly that squid proxy which is connected on main core router) and that is working fine. But, what happens when that proxy becomes unavailable to them? in that case their adsl line should tak over.
How to accomplish that? I have RIP running on network so routes are not the problems. All routers are aware of every routers routes. You can also see that proxy server goes out on ISP 1 to catch http traffic. So, i would like to configure routers in way that LAN clients in institution can go through proxy on internet and not just internet traffic, but also mail traffic (110 and 25) as long as that proxy is available. When it's not all traffic should go on their's adsl line.
I am aware that something like that should be accomplished by mark routing feature in mangle, but not so sure how. I tried everything, but the best solution that i've managed so far to accomplish is that internet traffic goes ok, but mail traffic goes on their adsl line. And when their's adsl line is not working their's mail is not working because that traffic is not passing through the main line, but through adsl line only.
Anyone with the idea hot to configure that? i assume that only two core routers are important to configure. On the main core router we already have situation with ISP redudancy that is working with routing marks, so i am a little bit confused why not in this new situation....
Please help..
