The tunnel can not establish successfully when we configure 2 or more LNS ip address in one L2TP gourp and tunnel load-sharing command.
we can ping the 2 LNS address form MA5200G normally.
1. when L2TP tunnel can not established for LAC, first ping the LNS ip address using the tunnel source ip address on MA5200G.
2. If ping successfully, check the tunnel parameter about pass, domain. etc.
3. check the ip routing-table on MA5200G to see if there are route load-balancing for LNS ip address.
In this case, we found the load-balancing for LNS ip address with 2 next-hop by 2 outgoing interface. After we remove one route for LNS, the tunnel can establish very well.
The data in one L2TP tunnel should be transftered in the same path in the network, especially the out going interface of LAC, if LAC have route load-balancing for LNS ip address, when the MA5200G initial the l2tp tunnel, it try to send the packets by 2 interface. In this case, the tunnel can not established.
when using L2TP tunnel, make sure that there is only one route for one LNS ip address in LAC.