TCP/IP ManagementTCP/IP ManagementTCP/IP ManagementTCP/IP Management

GO TCPADMGO TCPADM

TCP/IP Management

• Using the TCP/IP management tools to keep TCP/IP on your AS/400 robust, reliable and effective.

• Each option of the menu GO TCPADM has an associated command.

GO TCPADM

GO CFGTCP WRKTCPSTS=NETSTAT CFGTCPAPP VFYTCPCNN=PING STRTCP STRTCPFTP ENDTCP STRTCPTELN STRTCPSVR SNDTCPSPLF ENDTCPSVR WRKSBSJOB

The components of TCP/IP processing on the AS/400

include:

• The TCP/IP jobs• The physical connection over the line• The logical connection to the network• Optional SNMP services

TCP/IP Jobs• One of the jobs that is running named QTCPIP is the

controlling TCP/IP job.• Other jobs such as QTFTP*****, QTGTELNETS,

QTSMTP*****, QTWSG*****, QTLPD*****, QTPO***** , QTHTT***** also executed in QSYSWRK depending on your configuration.

The jobs that accompany QTCPIP are started in two ways: • Automatically, when the STRTCP is issued• Manually, through the use of the STRTCPSVR• TCP/IP functions that can be autostarted are

FTP, Telnet, SMTP, LPD, HTTP, WSG ,POP.• STRTCPSVR : options for the SERVER

parameter are *SNMP , *TELNET, * FTP , *SMTP, *LPD, *HTTP, *WSG , *POP

GO TCPADM• WRKCFGSTS To check the status of resources• VRYCFG To specify the names of the configuration objects to be varied on or off.• PING To confirm network connections and configuration• NETSTAT = WRKTCPSTS To display network status ( *IFC *RTE *CNN )• DSPMSG MSGQ(QTCP)• DSPLOG LOG(QHST)• WRKSBSJOB(QSYSWRK)

PING • Can help find problems in logical connections• If the connection is successful ,receives a return reply.• If the packet never returns, there is no route from the source

to the destination system and back again. This does not mean that TCP/IP is not configured correctly; it may mean that the routing is not established properly.

• If the packet does make a successful round trip, the time that it takes to make the round trip may be excessive. You may need to examine your network for potential performance or bottleneck problem

VFYTCPCNN• After configuring a system for TCP/IP

communications ,use PING command to ping the address ( or name) of the newly configured system.

• A successful PING doesn’t necessarily indicate that the system is properly configured to communicate in the network (routing and DNS issues may remain), but it does indicate the TCP/IP protocol is loaded properly.

NETSTAT/WRKTCPSTS

• The network status you can view are

• TCP/IP interface status *IFC• TCP/IP route information *RTE• TCP/IP connection status *CNN

TCP/IP interface status• This display shows the interfaces currently configured

on the system, including the loopback interface.• The interface status are: Active, Inactive, Ending,

Failed ,Starting ,RCYPND, RCYCNL• It’s a good idea to print the interface status fro

documentation purpose.

TCP/IP Route Information

• The route destination• The subnet mask of the destination

network ,sunnetwork, or system• The next hop IP address• A route available indication *yes --- the router is active and available *no --- the router is not available ,possibly due to an

inactive interface or a nonfunctioning router.

TCP/IP Route Information• The Route Information detail display is valuable for determining

whether a route exists in the AS/400 routing table.• For instance, PING is unsuccessful , you can examine the

routing table to determine whether a route exists to the remote system .If the route is available, the problem might be in the TCP/IP configuration of the remote system, the routing on the remote system, or invalid routing information . If the route is not available, direct your attention to the routers and lines in the network that are logically between the source and the destination systems.

TCP/IP connection status

• Listen--- the AS/400 is listening at the local port for an incoming connection

• Established--- the connection is established and the system are communicating

• Closed --- the connection has ended• Other states may be seen during a transition period• The ports( both remote and local) can use well-known names rather

than a port number. These names are defined in the service table modified by the command

WRKSRVTBLE

TCP/IP connection details

• The number of bytes in and out ( from AS/400 perspective) for this connection.

• The retransmission information gives the number of segments retransmitted by the AS/400 due to an acknowledgement not being received.

• If the number of retransmission is higher than the number that has been historically present for this connection, it could be an indication that there are network problems.

TCP/IP connection details

• The send window information identifies the current and largest size of the send window, or the number of bytes that can be transmitted without an acknowledgment.

• A large send window indicates that the network is successfully transmitting large packets without the need for retransmission.

• A small send window size means that the system has detected problems and has reduced the window size in an attempt to reduce the number of retransmissions.

Trouble Shooting

• If the TCP/IP services you want to enable are not functioning

Solution: Check QSYSWRK---- make sure the appropriate job is running in this subsystem

Trouble Shooting

• If a server process has been running but no longer functions and cannot be seen when WRKSBSJOB QSYSWRK

• Solution: Check the joblog for the missing process. By default joblogs go to the output queue QEZJOBLOG

Trouble Shooting

• If you got physical connection problem• Solution: WRKCFGSTS ---- make sure

*LIN, *CTL , *DEV are all in ACTIVE status. That enables communications across a line and start the QTCPIP job and associating the job with the line.

Trouble Shooting• If you got logical connection problem

• Solution: PING VFYTCPCNN If the connection is successful ,you can

receive a return reply

NETSTATWRKTCPSTS

Trouble Shooting

• If the connection is active and data is being transferred, F5 to refresh the screen should show a change in the byte counts. Otherwise probably means a recently broken connection, a network problem or a problem at the remote system.

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