rekan2 mau tanya neh..
sy coba set l2tp server dengan topologi serperti :
Click here to enlarge
ini adalah log di l2tp nya
jul/21 19:26:48 l2tp,debug tunnel 8 entering state: wait-ctl-conn
jul/21 19:26:48 l2tp,debug,packet sent control message to 10.88.8.15:1701
jul/21 19:26:48 l2tp,debug,packet tunnel-id=11837, session-id=0, ns=0, nr=1
jul/21 19:26:48 l2tp,debug,packet (M) Message-Type=SCCRP
jul/21 19:26:48 l2tp,debug,packet (M) Protocol-Version=0x01:00
jul/21 19:26:48 l2tp,debug,packet (M) Framing-Capabilities=0x1
jul/21 19:26:48 l2tp,debug,packet (M) Bearer-Capabilities=0x0
jul/21 19:26:48 l2tp,debug,packet Firmware-Revision=0x1
jul/21 19:26:48 l2tp,debug,packet (M) Host-Name="L2TP SERVER"
jul/21 19:26:48 l2tp,debug,packet Vendor-Name="MikroTik"
jul/21 19:26:48 l2tp,debug,packet (M) Assigned-Tunnel-ID=8
jul/21 19:26:48 l2tp,debug,packet (M) Receive-Window-Size=4
jul/21 19:26:48 l2tp,debug,packet rcvd control message from 10.88.8.15:1701
jul/21 19:26:48 l2tp,debug,packet tunnel-id=8, session-id=0, ns=1, nr=1
jul/21 19:26:48 l2tp,debug,packet (M) Message-Type=StopCCN
jul/21 19:26:48 l2tp,debug,packet (M) Result-Code=2
jul/21 19:26:48 l2tp,debug,packet Error-Code=6
jul/21 19:26:48 l2tp,debug,packet Error-Message="Tunnel auth failed for L2TP SERVER, no chal resp"
jul/21 19:26:48 l2tp,debug,packet 105(vendor-id=9)=0x00:01
jul/21 19:26:48 l2tp,debug,packet (M) Assigned-Tunnel-ID=11837
jul/21 19:26:48 l2tp,debug,packet sent control message (ack) to 10.88.8.15:1701
jul/21 19:26:48 l2tp,debug,packet tunnel-id=11837, session-id=0, ns=1, nr=2
jul/21 19:26:48 l2tp,debug tunnel 8 entering state: dead

mohon pencerahan..Click here to enlarge

Thanks.