The TCP port is used within the Abilis CPX to provide a transport service of Connection-Oriented type to the upper level ports which implement TCP/IP applicative services, such as the TELNET or HTTP ports.
The TCP port uses, at its lower level, the network service provided by the IP Router port.
The Transmission Control Protocol (TCP) supports the typical functionalities of the 4th level protocol of OSI architecture:
Connection-Oriented type communications;
Client/Server approach;
Control and Restore of the correct data flow in the communication;
fragmentation, ordering and data reassembling.
The TCP port is labelled within the Abilis CPX by the acronym "TCP" and it is provided with the parameters described in the following section:
The following example shows how to display parameters of TCP ports. Shown value are only examples.
[18:17:22] ABILIS_CPX: D P PO:901 PO:901 ------------------------------------------------------------------------ TCP sesnum:22 tcpwin:2048
All changes made on the TCP port parameters, displayed by low case characters, can be activated only restarting the system.
| SESNUM: | Number of TCP sessions |
| none | 0 - 255 |
It shows the number of maximum sessions that the TCP driver can manage. This value is automatically calculated by the system during the Validation procedure, according to the application services using the TCP port.
The parameter value is only informative and it cannot be modified.
| TCPWIN: | Size (in bytes) of the TCP window |
| 2048 | 2048 - 8192 (in bytes) |
It sets the size (in bytes) of the TCP window.
How to check the state and statistics of the TCP ports through the command D S.
[18:17:22] ABILIS_CPX: D D PO:901
PO:901 ------------------------------------------------------------------------
TCP ID TOP-State TCP/IP-State LocAdd-LocPort RemAdd-RemPort
------------------------------------------------------------------------
0 CONNECTED ESTABLISHED 192.168.000.253-23 192.168.000.002-1254
1 LISTEN LISTEN 000.000.000.000-2060
2 LISTEN LISTEN 000.000.000.000-23
3 LISTEN LISTEN 000.000.000.000-23
4 LISTEN LISTEN 000.000.000.000-23
-----------|---INPUT---|--OUTPUT---|-----------|---INPUT---|--OUTPUT---|
SEG | 4040| 5679|CHAR | 2403| 613710|
REP-SEG-UP | | 1|OPEN | 34| 0|
REP-SEG-DN | | 1|OPEN_FAIL | 0| 8|
CLOSE | 31| 2|RST | | 0|
------------------------------------------------------------------------
-----------|---INPUT---|--OUTPUT---|-----------|---INPUT---|--OUTPUT---|
CHK-ERR | 0| |ERR | 999| |
RST-SEG | | 999|CURR-ESTAB | 1| |
------------------------------------------------------------------------
Extended statistics are also available for the TCP ports. Here is an example on how to check them using the command D SE:
[18:17:22] ABILIS_CPX: D SE PO:901
PO:901 ------------------------------------------------------------------------
TCP --- Cleared 003:22:05:49 ago, on 12/05/2000 at 12:11:40 ----------------
ID TOP-State TCP/IP-State LocAdd-LocPort RemAdd-RemPort
------------------------------------------------------------------------
0 CONNECTED ESTABLISHED 192.168.000.253-23 192.168.000.002-1254
-----------|---INPUT---|--OUTPUT---|-----------|---INPUT---|--OUTPUT---|
SEG | 1366| 1971|CHAR | 842| 224216|
REP-SEG-UP | | 0|OPEN | 8| 0|
REP-SEG-DN | | 0|OPEN_FAIL | 0| 0|
CLOSE | 6| 1|RST | | 0|
------------------------------------------------------------------------
1 LISTEN LISTEN 000.000.000.000-2060
-----------|---INPUT---|--OUTPUT---|-----------|---INPUT---|--OUTPUT---|
SEG | 1771| 2614|CHAR | 977| 305591|
REP-SEG-UP | | 0|OPEN | 7| 0|
REP-SEG-DN | | 0|OPEN_FAIL | 0| 0|
CLOSE | 6| 1|RST | | 0|
------------------------------------------------------------------------
The information "Cleared DDD:HH:MM:SS ago, at DD/MM/YYYY HH:MM:SS", referred by the extended statistics, shows the time interval elapsed from the last reset of statistics (by the format "days:hours:minutes:seconds") and date/time of its execution (by the format "day:month:year" and "hours:minutes:seconds").
| ID: | TCP session identifier |
| 0 - (SESNUM: - 1) |
It identifies the TCP session.
| TOP-State: | Current state of the session |
| READY, LISTEN, CALLING, CONNECTED, CLOSING, UNDEFINED, ERR |
It shows the current state of the session.
| Driver | States | Meaning | Values shown in: | ||
|---|---|---|---|---|---|
| System Log | Debug Log | Display LCD | |||
| TCP (Session X25) | READY | The session is ready to send connection requests to the TCP/IP network, it means an application port of the upper level is able to make connection requests | |||
| LISTEN | The session is ready to receive connection requests coming from the TCP/IP network, it means an application port of the upper level is waiting the connection requests | ||||
| CALLED | Session is going to open the connection | ||||
| CALLING | |||||
| CONNECTED | Session is connected | ||||
| CLEARED | Session is going to clear the connection | ||||
| CLEARING | |||||
| UNDEFINED | Session is into an error state | ||||
| ERR | Software error. Contact the Abilis assistance. | ||||
| TCP/IP-State: | Current state of the TCP level connection |
| CLOSED, LISTEN, SYN-SENT, SYN-RCVD, ESTABLISHED, FIN-WAIT-1, FIN-WAIT-2, CLOSE-WAIT, LAST-ACK, CLOSING, TIME-WAIT, DELETE-TCB, UNDEFINED, ERR |
It shows the current state of the TCP level connection.
| Driver | States | Meaning | Values shown in: | ||
|---|---|---|---|---|---|
| System Log | Events Log | Display LCD | |||
| TCP (TCP connection) | CLOSED | Connection is closed | |||
| LISTEN | The driver is waiting connection requests | ||||
| SYN-SENT | The driver sent a connection request | ||||
| SYN-RCVD | The driver received a connection request | ||||
| ESTABLISHED | Connection established | ||||
| FIN-WAIT-1 | Active closing. The driver sent a disconnection request. | ||||
| FIN-WAIT-2 | Active closing. The driver received an acknowledgement to a disconnection request | ||||
| CLOSE-WAIT | Passive closing. The driver received a disconnection request | ||||
| LAST-ACK | Passive closing. The driver sent the last acknowledgement to a disconnection request | ||||
| CLOSING | Both parts require the connection to be closed | ||||
| TIME-WAIT | Session closed. The driver will reach the state CLOSED (after the time-out) | ||||
| DELETE-TCB | Error detected. Contact the Abilis assistance. | ||||
| UNDEFINED | |||||
| ERR | Software error, contact the Abilis assistance | ||||
| LocAdd: | IP local address used by the connection |
| 0 - 255.255.255.255 |
It shows the IP local address used by the TCP connection, only if it is not in the state CLOSED.
| LocPort: | Number of the IP local port used by the connection |
| 0 - 65535 |
It shows the number of the IP local port used by the TCP connection, only if it is not in the state CLOSED.
| RemAdd: | IP remote address used by the connection |
| 0 - 255.255.255.255 |
It shows the IP remote address used by the TCP connection, only if it is not in the state CLOSED or LISTEN.
| RemPort: | Number of the IP remote port used by the connection |
| 0 - 65535 |
It shows the number of the IP remote port used by the TCP connection, only if it is not in the state CLOSED or LISTEN.
| SEG: | Overall number of segments received/sent in all the sessions |
| 0 - 4.294.967.295 |
The counter SEG (INPUT) is incremented every time a frame is received, while the SEG (OUTPUT) one every time it is sent.
| CHAR: | Overall number of characters received/sent in all the sessions |
| 0 - 4.294.967.295 |
The counter CHAR (INPUT) is incremented every time a frame is received, while the CHAR (OUTPUT) one every time it is sent
| REP-SEG-UP: | Overall number of segments repeated in all the sessions when session state is UP |
| 0 - 4.294.967.295 |
The counter REP-SEG-UP (OUTPUT) is incremented every time a frame is repeatedly sent on UP state.
| REP-SEG-DN: | Overall number of segments repeated in all the sessions when session state is DOWN |
| 0 - 4.294.967.295 |
The counter REP-SEG-DN (OUTPUT) is incremented every time a frame is repeatedly sent on DOWN state.
| OPEN: | Overall number of OPENs in all the sessions |
| 0 - 4.294.967.295 |
The counter OPEN (OUTPUT) is incremented every time that the session state changes from CLOSED to SYN-SENT (correspondent to sending a connection request).
The counter OPEN (INPUT) is incremented every time that the session state changes from CLOSED to SYN-RCVD (correspondent to receiving a connection request).
| OPEN_FAIL: | Overall number of failed attempts to establish a connection |
| 0 - 4.294.967.295 |
The counter OPEN-FAIL is incremented every time a connection establishment fails. Input/Output indicates on which call direction there were the failure.
| CLOSE: | Overall number of connections closed |
| 0 - 4.294.967.295 |
The counter CLOSE is incremented every time a connection established is closed. Input/Output indicates on which direction there were the closure (input=close started from remote host. output=close started locally).
| RST: | Overall number of connection reset |
| 0 - 4.294.967.295 |
The counter ESTAB-RST (OUTPUT) is incremented every time the connection state changes from ESTABLISHED or CLOSE-WAIT to CLOSED (correspondent to the connection clearing).
| CHK-ERR: | Overall number of checksum errors detected during reception of segments |
| 0 - 4.294.967.295 |
The counter CHK-ERR (INPUT) is incremented every time a segment, containing a checksum error, is received.
| ERR: | Overall number of bad segments received |
| 0 - 4.294.967.295 |
The counter ERR (INPUT) is incremented every time a segment, containing an error, is received.
| RST-SEG: | Overall number of segments sent with "RST" |
| 0 - 4.294.967.295 |
The counter RST-SEG (OUTPUT) is incremented every time a segment containing the "RST" information, is sent.
| CURR-ESTAB: | Overall number of connections whose state is ESTABLISHED or CLOSED-WAIT |
| 0 - 4.294.967.295 |
The counter CURR-ESTAB (INPUT) shows the overall number of connections whose state is ESTABLISHED or CLOSED-WAIT
Fields displayed by the extended statistics are the same of the ones showed by the execution of the command D S, but they refers to the single session of the TCP port.
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