Proposal mismatch
Symptom
The proposals mismatch.
Analysis
The following is the debugging information:
got NOTIFY of type NO_PROPOSAL_CHOSEN
Or
drop message from A.B.C.D due to notification type NO_PROPOSAL_CHOSEN
The two parties in the negotiation have no matched proposals.
Solution
For the negotiation in phase 1, look up the IKE proposals for a match. For the negotiation in phase 2, check whether the parameters of the IPsec policies applied on the interfaces are matched, and whether the referred IPsec proposals have a match in protocol, encryption and authentication algorithms.