Examples of managing VTAM

Here are examples of some of the VTAM commands that you might use in a z/OS network administration role for controlling VTAM.

Like all z/OS environments, VTAM allows the use of some abbreviations instead of the full command syntax. Some automation software products have taken this a step further and provided command executables that eliminate the need to know the full VTAM command syntax. For detailed information about commands and examples, refer to z/OS Communications Server SNA Operation, which contains VTAM operations and commands.

Examples of displaying VTAM resources

Enterprise Extender (EE) is being used by many customers to carry SNA traffic over IP networks. One of the most commonly used commands to check the status of an EE network is illustrated in Figure 1.

The DISPLAY NET,EE command (DISPLAY can be abbreviated as D) gives the network administrator a quick look at the remote IP endpoint of an EE session. In this sample, the remote endpoint was 192.168.80.90. The command output provides the line and PU (physical unit) information as well as other node characteristics.

You can see some information on the connection beginning at IST2035I. NLP stands for network layer packet. The NLPs retransmitted count can be used to gauge the amount of lost traffic over the session.

Figure 1. DISPLAY of remote Enterprise Extender endpoint

 D NET,EE,IPADDR=(,192.168.80.90)
 IST097I DISPLAY ACCEPTED
 IST350I DISPLAY TYPE = EE
 IST2001I  ENTERPRISE EXTENDER CONNECTION INFORMATION
 IST924I -------------------------------------------------------------
 IST1680I LOCAL IP ADDRESS 192.168.80.9
 IST1910I LOCAL HOSTNAME VIPA16.SSCP1A.TCP.RALEIGH.IBM.COM
 IST1680I REMOTE  IP ADDRESS 192.168.80.90
 IST1909I REMOTE HOSTNAME VIPA16.SSCP2A.TCP.RALEIGH.IBM.COM
 IST2022I EE CONNECTION ACTIVATED ON 09/12/05 AT 09:27:15
 IST2023I CONNECTED TO LINE LNEE1000
 IST2024I CONNECTED TO SWITCHED PU SWEE2A1
 IST2025I LDLC SIGNALS RETRANSMITTED AT LEAST ONE TIME    =         0
 IST2026I LDLC SIGNALS RETRANSMITTED SRQRETRY TIMES       =         0
 IST2009I RTP PIPES =          7      LU-LU SESSIONS      =         6
 IST2027I DWINOP  = NO      REDIAL = *NA*        REDDELAY =      *NA*
 IST2028I KEEPACT = NO
 IST2029I MTU SIZE = 1232
 IST924I -------------------------------------------------------------
 IST2035I TOTALS FOR ALL PORT PRIORITIES
 IST2036I   NLPS SENT           =                95182  ( 095K )
 IST2037I   BYTES SENT          =             10787917  ( 010M )
 IST2038I   NLPS RETRANSMITTED  =                    0  ( 000K )
 IST2039I   BYTES RETRANSMITTED =                    0  ( 000K )
 IST2040I   NLPS RECEIVED       =                95227  ( 095K )
 IST2041I   BYTES RECEIVED      =              9756692  ( 009M )
 IST2042I 1 OF 1 EE CONNECTIONS DISPLAYED
 IST314I END

A network administrator might want information on a reported problem with an APPN RTP ( rapid transport protocol) link. The administrator would use the DISPLAY NET,RTPS command.

In Figure 2 , the RTP PU cnr00004 is being tested. An RTP PU represents the endpoint of an HPR route. The result of this command is a display, in message IST1792I, of the total time taking to traverse the route. Routing delays in SNA can be of significant impact for time sensitive applications. The advantage of this test command is that the network administrator might be able to determine quickly whether the reported problem is really with the link, or whether the delay is being introduced by an application.

Figure 2. DISPLAY of the HPR route test

 D NET,RTPS,ID=cnr00004,TEST=yes
 IST097I DISPLAY ACCEPTED
 IST350I DISPLAY TYPE = RTPS
 IST1695I PU NAME       CP NAME      COSNAME SWITCH CONGEST STALLSESS
 IST1960I CNR00004 NETA.SSCP2A       #INTER    NO     NO     NO     1
 IST1786I HPR ROUTE TEST INITIATED FOR RTP PU
 IST1454I 1 RTP(S) DISPLAYED
 IST314I END
 IST1787I HPR ROUTE TEST RESULTS FOR RTP PU CNR00004
 IST1788I NODE CP NAME    TG NUMBER  PARTNER CP NAME  INTERNODAL TIME
 IST1789I                                             (MILLISECONDS)
 IST1790I NETA.SSCP1A       21       NETA.SSCP2A                  1
 IST1792I TOTAL RTP TRAVERSAL TIME 1 MILLISECONDS
 IST314I END

Examples of changing VTAM resources

The primary command used for controlling VTAM is the VARY command.

Note: Ensure you understand the VARY and MODIFY commands well before using them. Your security profile as a z/OS network administrator provides you with the ability to fully control the network and its resources. Always verify that the resource you are changing or modifying is the correct one--and understand the impact.

VARY command

The VARY command affects the status of the physical resource and session. Usually, a vary command results in a complete state change from active to inactive or the opposite. The vary command is abbreviated as the single character V.

The following command activates a VTAM resource that might be in an inactive state or a new VTAM resource you have just created:

V NET,ACT,ID=resource

Figure 3. The VARY ACT command

 V NET,ACT,ID=Z6TMD005   
 IST097I VARY ACCEPTED   
 IST093I Z6TMD005 ACTIVE

The following command inactivates a VTAM resource that might be in an active state, have a problem, or needs to be made inactive in order to modify it, and then reactivate it:

 V NET,INACT,ID=resource

Figure 4. The VARY INACT command

 V NET,INACT,ID=Z6TMD005             
 IST097I VARY ACCEPTED               
 IST105I Z6TMD005 NODE NOW INACTIVE

The MODIFY command

The MODIFY command enables you to change VTAM options, tables, storage and traces. Usually, a modification command results in a change in the characteristics of a resource, but does not change it from a state of active to inactive or the opposite.

The modify command is abbreviated as the single character F:

F NET,VTAMOPTS,startoption=option

This command allows you to modify VTAM start options; with some options there are restrictions and dependencies. If your VTAM was defined as an interchange node (ICN) containing both subarea and APPN support, you might want to change the VTAM search order (SORDER) option.

If the current setting was set to SUBAREA, you might want to change it to APPNFRST. You would do this with the following command:

F NET,VTAMOPTS,SORDER=APPNFRST

The following command enables you to turn on a VTAM buffer for a particular resource:

F NET,TRACE,id=resource,TYPE=BUF

The following command stops the VTAM buffer trace:

F NET,NOTRACE,ID=resource,TYPE=BUF

Figure 5 shows the use of these commands.

Figure 5. VTAM buffer trace started, then stopped on a VTAM LU

 F NET,TRACE,ID=Z6TS0001,TYPE=BUF         
 IST097I MODIFY ACCEPTED                  
 IST1515I BUFFER TRACE ACTIVE             
 IST513I TRACE INITIATED FOR NODE Z6TS0001
 F NET,NOTRACE,ID=Z6TS0001,TYPE=BUF          
 IST097I MODIFY ACCEPTED                     
 IST512I TRACE TERMINATED FOR NODE = Z6TS0001

The HALT command

This command is used to stop VTAM--which is not something you want to test on your production LPAR! A HALT command without any parameters performs a nondisruptive end to VTAM. The HALT command is abbreviated as the single characterZ .

The following command halts VTAM more quickly than a normal HALT command. The command causes sessions to be terminated and VTAM to shut down.

Z NET,QUICK

The following command causes VTAM to abend and is quite a nasty way to bring it down. You would normally try the Z NET,QUICK command first.

Z NET,CANCEL