PPPOA (dynamic IP)
                                                               +------+
   eth0 (PUBLIC PPPoE)                         +---------------|MODEM |
+-------------+                                |  192.168.2.100+------+
| LINUX router| eth2 (192.168.2.101/24)--------+
+-------------+
  eth1 192.168.2.254/24

eth0 and eth2 are NATTED, the problem is that its routing to eth2 instead of eth0, i already created a routing table for it. When i investigate at the tcpdump its seems that it cause due eth1 and eth2 are on the same subnet. im thinking to use /30 on eth2.