One loopback address at MA5200G cannot ping through from foreign web and cannot ping through in equipment connected with MA5200G. Check route of MA5200G loopback address and it is normal.
1. Check route at upper equipment. There is route to loopback address but it cannot ping through. Ping other address and it is normal.
2. Check the configuration at MA5200G. Find that loopback address and LNS group are bound and SPU is bound under LNS group.
3. Check MA5200G board configuration with dispaly device. There is no SPU. Because one loopback address binds LNS group and SPU, packets to this loopback will be handled by bound SPU. If there is no SPU, all packets are discarded.
After loopback address is bound with lns-group, packets with PING loopback address is sent to tunnel board. After the tunnel board is plugged, packets cannot be handled and loopback address cannot ping through.
When tunnel board at MA5200G is plugged, delete configuration under LNS-group once lns-group binds loopback address. Otherwise there is problem.