Creating configuration objects, especially lines, controllers and devices for communications, can be a time-consuming and frustrating job. You have to make sure you have all of the parameters specified correctly on the object or it may not work the way you intended -- or at all. That means once you finally have your configuration objects created and running correctly, you will want to ensure that you don't have to recreate them from scratch. One way to protect yourself is to save the objects as part of your save strategy, which is highly recommended. If you have to, you can always go back to the tape or save file and retrieve them. However, that method can also be time-consuming. Fortunately, IBM has given us another way to recreate the objects: the Retrieve Configuration Source (RTVCFGSRC) command.
The RTVCFGSRC command allows you to store the create commands for your configuration objects in a command language source member (or a set of members, depending on how your use the command). You can keep the source file on your system. Then if you need to quickly recreate the configuration objects, you can compile the source member and run the resulting program. A good example of when you might need to do that is when someone accidentally deletes the configuration object and you need to quickly recreate it to get things working again.
I like to use RTVCFGSRC when I am modifying an existing configuration object to make it work in a new environment or to tune it to work better in an existing environment. As a very simple example, suppose my network team is upgrading the company's Ethernet service from 10M to 100M. I want to take advantage of the faster speed, and the hardware I have will allow me to do so. I need to just reconfigure my existing Ethernet line description. In this case I need to change the LINESPEED and LINKSPEED parameters from 10M to 100M. But what if the change was more complicated? It would be a good idea to have the old configuration saved before starting to change parameters using the CHGLINETH command.
To save the configuration source, you can type RTVCFGSRC at a command line. When you hit enter you will see a display like the one in Figure 1:
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Retrieve Configuration Source (RTVCFGSRC)
Type choices, press Enter.
Configuration description . . . Name, generic*, *ALL
+ for more values
Type . . . . . . . . . . . . . . *ALL, *NWSD, *NWID, *LIND...
Source file . . . . . . . . . . QCLSRC Name, QCLSRC
Library . . . . . . . . . . . *LIBL Name, *LIBL, *CURLIB
Source member . . . . . . . . . *CFGD Name, *CFGD
Bottom
F3=Exit F4=Prompt F5=Refresh F10=Additional parameters F12=Cancel
F13=How to use this display F24=More keys
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Figure 1: The RTVCFGSRC command
You can enter the line description name and the type and specify the source file and member name, as shown in Figure 2. Note that in Figure 2 *CFGD was used for the source member parameter, which will create a source member in MYLIB/QCLSRC with a name of MYLINE (from the configuration description parameter).
You can specify either *NET or *OBJ for the retrieve option parameter. *OBJ will give you the source for just the object specified, but *NET will give you the source for that object and any objects below it in the configuration hierarchy. For a line description, *NET will retrieve the source for the lind and any ctld and devd objects that are attached to the line. I usually specify *NET and then if I find later that I need to create only one of the objects, I can copy the create command for the specific object into a different source file or modify the existing source file, commenting out or deleting what I don't need.
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Retrieve Configuration Source (RTVCFGSRC)
Type choices, press Enter.
Configuration description . . . > MYLINE Name, generic*, *ALL
+ for more values
Type . . . . . . . . . . . . . . > *LIND *ALL, *NWSD, *NWID, *LIND...
Source file . . . . . . . . . . > QCLSRC Name, QCLSRC
Library . . . . . . . . . . . > MYLIB Name, *LIBL, *CURLIB
Source member . . . . . . . . . *CFGD Name, *CFGD
Retrieve option . . . . . . . . *NET *NET, *OBJ
Bottom
F3=Exit F4=Prompt F5=Refresh F10=Additional parameters F12=Cancel
F13=How to use this display F24=More keys
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Figure 2: Filling in the RTVCFGSRC command
If you view the source member that you just created, you will see something like what's shown in Figure 3.
Columns . . . : 1 80 Edit MYLIB/QCLSRC
SEU==> MYLINE
FMT ** ...+... 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... 8
*************** Beginning of data ********************************************************
0000.01 /* MYLINE 11/07/05 13:58:34 */ 051107
0000.02 CRTLINETH LIND(MYLINE) RSRCNAME(CMN01) ONLINE(*YES) + 051107
0000.03 VRYWAIT(*NOWAIT) MAXCTL(40) ADPTADR(*ADPT) + 051107
0000.04 EXCHID(05600441) ETHSTD(*ALL) LINESPEED(10M) + 051107
0000.05 DUPLEX(*FULL) MAXFRAME(1496) SSAP((04 1496 *SNA)(12 1496 + 051107
0000.06 *NONSNA)(AA 1496 *NONSNA)(C8 1496 *HPR)) THRESHOLD(*OFF) + 051107
0000.07 GENTSTFRM(*YES) LINKSPEED(10M) COSTCNN(0) COSTBYTE(0) + 051107
0000.08 SECURITY(*NONSECURE) PRPDLY(*LAN) USRDFN1(128) + 051107
0000.09 USRDFN2(128) USRDFN3(128) AUTOCRTCTL(*NO) CMNRCYLMT(2 5) + 051107
0000.10 MSGQ(*SYSVAL) TEXT('ethernet line description for mysys') 051107
0000.11 CRTCTLNET CTLD(MYCTL) ONLINE(*NO) LINE(MYLINE) CNNRSPTMR(170) + 051107
0000.12 TEXT('CREATED BY AUTO-CONFIGURATION') 051107
0000.13 CRTDEVNET DEVD(MYDEV) TYPE(*TCPIP) ONLINE(*NO) CTL(MYCTL) + 051107
0000.14 TEXT('CREATED BY AUTO-CONFIGURATION') 051107
****************** End of data ******************************************************************************************
Figure 3: Source member created by RTVCFGSRC
After you verify that the source has been created, you can modify the existing line description for MYLINE as much as you want, knowing that if you get to a point where you need to get back to the original, you can simply delete the existing MYLINE, MYCTL, and MYDEV objects, compile source file MYLINE and run the resulting MYLINE program.
You may even want to create a job scheduler entry to retrieve your communication configuration source periodically so that you always have a recent copy of your communications setup. This can save a lot of time if something is deleted.
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About the author: Dan Reusche is a senior systems administrator at Think Federal Credit Union in Rochester, Minn. He has worked with the IBM AS/400 and iSeries platform since 1988, when he worked at the IBM Rochester Development Lab and support of AS/400 systems used within IBM. You may contact him at dreusche@chartermi.net.
