6-2
Section
Using Socket Services with Socket Service Request Switches
107
Area until a socket is opened again. Writing data to the DM Area, however, is not
synced with writing to the Socket Status Areas, and timing may vary somewhat.
TCP connection status
–
–
–
–
–
–
–
–
–
–
–
–
m+9 to m+16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Status in indicated in bits 0 to 3 using the 1-digit hexadecimal codes shown in the
following table.
Code
Status
Meaning
0
CLOSED
Connection closed.
1
LISTEN
Waiting for connection.
2
SYN SENT
Active and waiting for SYN.
3
SYN
RECEIVED
SYN sent and received.
4
ESTABLISHED
Connection established.
5
CLOSE WAIT
FIN received and waiting for close.
6
FIN WAIT1
Finished and FIN sent.
7
CLOSING
Finished and FIN exchanged. Waiting for
acknowledgement of FIN arrival.
8
LAST ACK
FIN received and finished. Waiting for acknowledgement
of FIN arrival.
9
FIN WAIT2
FIN arrival acknowledged. Waiting for FIN.
A
TIME WAIT
Finished and waiting for silence for twice the maximum
segment life (2MSL).
6-2-6 Socket Services and Socket Status
When using socket services, it is important to consider the timing of the status
changes in the Socket Status Area. The diagram below shows a flowchart for
opening UDP.
