Section 2, Task 1: Customize and Verify Your Test PDB Action 7a: Check the results

Depending on the vendor of a network device, some metrics are set by hand at configuration time. To assure that they were typed correctly, check the configuration of your network devices to assure that the following variables have appropriate values:

• IFDESC, whose values are used to identify interfaces (if this string variable has Kept status of Yes in your PDB)
  
  
• IFSPEED, whose values are crucial in calculation utilization (if this string variable has Kept Status of Yes in your PDB)
  
  
• any other variables that were entered manually when the network devices were configured.

In table HN2IFT, the calculation of ifUtilization (IFUTIL) in IT Service Vision uses the value of ifSpeed (IFSPEED). Frequently, ifSpeed is established for each interface of each network device manually by the technician configuring the device. There is no automatic validity check; the value could be incorrect. Using other configuration information that you have, you need to assure yourself that the values being reported for ifSpeed are indeed correct.

Another consideration of using ifSpeed and ifUtilization is determining whether an interface is half-duplex or full-duplex. In the calculation of ifUtilization that is supplied with IT Service Vision, all interfaces are assumed to be half-duplex. Interface utilization is thus calculated using the sum of input and output octets

ifutil = (ifiocts+ifoocts)*8 / ifspeed

If you use concentrators on your lines or if the interface is full-duplex, utilization may sometimes be reported as exceeding 100%. For a line with concentrators, this is the only meaningful indicator of how much of the capacity of the line is being consumed. However, the utilization of full-duplex interfaces is more meaningfully reported as the maximum of input and output octets

ifutil = max(ifiocts,ifoocts)*8 / ifspeed

To identify to IT Service Vision which of your interfaces are full-duplex, replace the supplied SAS informat definition (which presumes all interfaces are half-duplex) with your own definition that identifies which interfaces at your site are full-duplex. Follow these steps:

1. Check that you started the IT Service Vision server with the SITEACC= parameter set to write.
   
   
2. In the PROGRAM EDITOR window, type this program starting at the first line in the body of the window

   proc format library=sitelib.cpfmts;
   invalue CSFDX
   'hostname instance' = 1
   'hostname instance' = 1
   .
   .
   .
   other = 0;
   run;

   where hostname and instance identify a full-duplex interface and a single blank separates them. The reference to sitelib indicates that this informat is being stored in your SITELIB library and will be accessible to everyone at your site.

   For example, suppose your IT Service Vision site library is /usr/cpe/sitelib, the number 2 interface on dimes.unx.sas.com and the number 4 interface on swimmer.unx.sas.com are full-duplex, and all other machines and interfaces are not full-duplex. Your informat definition program would look like this:

   proc format library=sitelib.cpfmts;
   invalue CSFDX
   'dimes.unx.sas.com 2' = 1
   'swimmer.unx.sas.com 4' = 1
   other = 0 ;
   run;

3. Submit the above commands.
   
   
4. To check the format, type this program in your PROGRAM EDITOR window, starting at the first line in the body of the window:

   proc fsview data=detail.hn2ift;
   where input(trim(machine)||" "||left(put(instans,7.)),CSFDX.);
   run;

5. Submit it. In the FSVIEW window, there should be one observation for each full-duplex interface and no other observations.
   
   
6. Close the FSVIEW window.

The SAS informat CSFDX is used by the IT Service Vision process step when it calculates ifUtilization, so for the utilization calculation to be done properly you must run the above statements before you run the process step.

If you add or change full-duplex interfaces, you will need to run these statements again. The new information will be utilized the next time that you run the process step.