Hi Furuzi,
I see you old post about tunnel disconnection and I encounter the same. I tried many versions of routerOS, many CISCO parameters and I still got a tunnel disconnection on all my Mikrotik LNS... except one
.
I've sorted the Cisco logs and it seems that after a period of time, Mikrotik does not send ICRP or ZLB anymore to maintain the tunnel. I also tried without L2TP tunnel authentication and it's the same behavior. in green the normal operation for many days, IRCQ and ZLB ack, in orange Cisco does not receive ICRP, in red, timeout, start of disconnecting PPP in tunnel, and then tunnel reset:
2021-08-25 10:52:20.655 172.31.131.2 L2TP tnl 2167B4:0000D22B: FSM-CC ev Session-Conn
2021-08-25 10:52:20.655 172.31.131.2 L2TP tnl 2167B4:0000D22B: Search for cc: found existing cc
2021-08-25 10:52:20.655 172.31.131.2 L2TP tnl 2167B4:0000D22B: Session count now 345
2021-08-25 10:52:25.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend CDN, flg TLS, ver 2, len 55
2021-08-25 10:52:25.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICCN, flg TLS, ver 2, len 177
2021-08-25 10:52:26.040 172.31.131.2 L2TP tnl 2167B4:0000D22B: Rx Hello, flg TLS, ver 2, len 20
2021-08-25 10:52:26.040 172.31.131.2 L2TP tnl 2167B4:0000D22B:
2021-08-25 10:52:26.040 172.31.131.2 L2TP tnl 2167B4:0000D22B:
2021-08-25 10:52:26.040 172.31.131.2 L2TP tnl 2167B4:0000D22B: Tx ZLB ACK to ZH_PPPoE_Core tnl 120
2021-08-25 10:52:26.040 172.31.131.2 L2TP tnl 2167B4:0000D22B:
2021-08-25 10:52:33.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend CDN, flg TLS, ver 2, len 55
2021-08-25 10:52:33.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICRQ, flg TLS, ver 2, len 92
2021-08-25 10:52:33.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICCN, flg TLS, ver 2, len 177
2021-08-25 10:52:41.650 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICCN, flg TLS, ver 2, len 177
2021-08-25 10:52:41.650 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICRQ, flg TLS, ver 2, len 92
2021-08-25 10:52:41.650 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend CDN, flg TLS, ver 2, len 55
2021-08-25 10:52:49.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: Retransmit timer temporarily adjusted from 8000 ms to 1000 ms
2021-08-25 10:52:50.650 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICCN, flg TLS, ver 2, len 177
2021-08-25 10:52:50.650 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend CDN, flg TLS, ver 2, len 55
2021-08-25 10:52:50.650 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICRQ, flg TLS, ver 2, len 92
2021-08-25 10:52:58.650 172.31.131.2 L2TP tnl 2167B4:0000D22B: Retransmit timer temporarily adjusted from 8000 ms to 1000 ms
2021-08-25 10:52:59.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend CDN, flg TLS, ver 2, len 55
2021-08-25 10:52:59.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICRQ, flg TLS, ver 2, len 92
2021-08-25 10:52:59.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICCN, flg TLS, ver 2, len 177
2021-08-25 10:53:07.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend CDN, flg TLS, ver 2, len 55
2021-08-25 10:53:07.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICCN, flg TLS, ver 2, len 177
2021-08-25 10:53:07.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: O Resend ICRQ, flg TLS, ver 2, len 92
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: General error - refer to error code
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: Vendor specific
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: Error Code
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: Optional Message
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: FSM-CC established->Wt-STOPACK
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: Shutting down tunnel
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: Vendor Error
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: FSM-CC do Tx-StopCCN
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: FSM-CC ev Shut
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: Tunnel shut
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: "Too many retransmits to 172.31.150.211"
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B:
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: Result Code
2021-08-25 10:53:15.649 172.31.131.2 L2TP tnl 2167B4:0000D22B: With 345 sessions
2021-08-25 10:53:15.650 172.31.131.2 L2TP tnl 2167B4:0000D22B: FSM-CC in Wt-STOPACK
2021-08-25 10:53:15.650 172.31.131.2 L2TP tnl 2167B4:0000D22B: VPDN Session count now 344
2021-08-25 10:53:15.650 172.31.131.2 L2TP tnl 2167B4:0000D22B: Session count now 343
I also tried with physical router instead of CHR, changing path, splitting tunnels to limit PPP. Nothing correct this tunnel lost.
Does anyone have stable L2TP LNS tunnels ?
Best Regards