I recommend you to use only one router (to simplify), and use two little cheap routers (the ones that your ISP gives for almost free) for sending the Internet IPs to your Cisco router (firewall). (Maybe it's the configuration you'r telling about...)
Although I believe OER is the solution to all of our problems, I haven't tested it, and haven't seen it working well, maybe it's a rock to use it just for a two ISP load-sharing configuration...
My very simple recomendation is:
int F0
description Local interface
ip address 192.168.0.1 255.255.255.0
ip nat inside
int F1
description Outside interface
ip address
ip address secondary
ip nat outside
ip route 0.0.0.0 0.0.0.0
ip route 0.0.0.0 0.0.0.0
ip nat pool POOL1 prefix-length 24
ip nat pool POOL2 prefix-length 24
ip nat inside source route-map LAN-ISP1 pool POOL1 overload
ip nat inside source route-map LAN-ISP2 pool POOL2 overload
!
access-list 1 remark Gateway for ISP1
access-list 1 permit
access-list 2 remark Gateway for ISP2
access-list 2 permit
access-list 100 remark LAN 192.168.0.x to outside
access-list 100 permit ip 192.168.0.0 0.0.0.255 any
!
route-map LAN-ISP1 permit 10
match ip address 100
match ip next-hop 1
route-map LAN-ISP2 permit 10
match ip address 100
match ip next-hop 2
This configuration can be more complex using sla to ensure lines are up before bringing up the default routes, but maybe these few lines are easier to understand and deploy. (With this working you can improve it later, the only problem is that with this configuration when a ISP fails all your connection fails)
One recomendation is not using load-sharing per-packet, use per-destination (the default issue), maybe it won't load-share 50%/50%, but it really works with two different ISPs without BGP (I think it's the real thing here).
Good routing, see U on Internet:
Fazerbcn
