TCP previous segment lost
From this tcpdump
12.12.12.12 is ip client , 100.100.100.13 is ip Virtual server
12.12.12.12 100.100.100.13 TCP 66 4204 > http [SYN] Seq=0 Win=65535 Len=0 MSS=1460 SACK_PERM=1
100.100.100.13 12.12.12.12 TCP 66 http > 4204 [SYN, ACK] Seq=0 Ack=1 Win=4380 Len=0 MSS=1460 SACK_PERM=1
12.12.12.12 100.100.100.13 TCP 64 4204 > http [ACK] Seq=1 Ack=1 Win=65535 Len=0
12.12.12.12 100.100.100.13 HTTP 124 POST /WSCDS/services/WSCDS?wsdl HTTP/1.1 [Packet size limited during capture]
12.12.12.12 100.100.100.13 HTTP 124 [TCP Previous segment lost] Continuation or non-HTTP traffic[Packet size limited during capture]
100.100.100.13 12.12.12.12 TCP 60 [TCP ACKed lost segment] http > 4204 [ACK] Seq=1 Ack=2049 Win=6428 Len=0
12.12.12.12 100.100.100.13 HTTP 124 Continuation or non-HTTP traffic[Packet size limited during capture]
100.100.100.13 12.12.12.12 TCP 60 [TCP ACKed lost segment] http > 4204 [ACK] Seq=1 Ack=2479 Win=6858 Len=0
what the meaning and what cause of TCP Previous segment lost ?
thank you