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VPN Central Gateway drops SIP RTP traffic between the SIP Call Manager and the phone behind VPN Satellite Gateway, where the SIP call was initiated
Symptoms
  • During SIP conference calls in VPN Star community, some parties are unable to speak or be heard.

  • VoIP traffic / call is functional in one direction only.

  • Kernel debug on VPN Central Gateway ('fw ctl debug -m fw + drop' and 'fw ctl debug -m VPN + packet') shows that it drops the SIP RTP traffic between the SIP Call Manager and the VPN Satellite Gateway where the SIP call was initiated:

    ;fw_log_drop: Packet proto=17 ... dropped by chain_ipsec_methods_ok Reason: vpn_decrypt_methods_ok failed;
    ... ...
    ;chain_ipsec_methods_ok: No decryption message;
    ... ...
    ;fw_log_drop: Packet proto=17 ... dropped by chain_ipsec_methods_ok Reason:  No decryption message;
    ... ...
    

    Another possible drop reason for the returned VoIP packets:

    ;fw_log_drop_ex: Packet proto=17 ... dropped by vpn_decrypt_verify Reason: CONN_ENC_NO_ENTRY[_SR] with packet reversed to the original direction of the connection;
    
Solution
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