A Cisco 1841 with two ADSL modules are implemented for load balancing. Both ADSL links are configured with PPPoE for Internet access. However, there is an obvious traffic drop in the implementation. We found that the data lost is caused by the mal-function of NAT. What we want is that traffic exiting interface Dialer1 will be translated to Dialer1's IP, while those exiting Dialer2 translated to Dialer2's. However, some traffic exiting interface Dialer1 will be translated to Dialer2's IP, and vice versa.
We did a workaround for this problem by doing NAT one more time. Hence the access-list 10 includes an entry 188.8.131.52/16, which is the IP range assigned to PPPoE client by the ISP.
However, the problem is not totally solved since some connection will drop occasionally.
Any one have a better implementation than this or any advise is greatly appreciated!