irrelevant objects in a row

[Juergen Quittek <quittek@ccrle.nec.de>]

Hi all,

I'm sketching a draft for a MIDCOM MIB and ran into a question on
table design.

I have a table of midcom policy rules. A table entry contains an
enum object called ruleType indicating the kind of rule of this row.

Now, for describing policy rules, not always all columns are required.
For certain values of the ruleType object, some columns are irrelevant

I wonder what is the best way of handling these columns.
I can see three alternatives:

 - Is it fine just to state in the DESCRIPTION clause that for certain
   values of ruleType the values of these columns are irrelevant?

 - Shall I define a special value for these objects indicating they
   are irrelevant?  This might not be possible in some cases,
   for example if it contains an IP address.

 - Shall the DESCRIPTION clause require the object to be not accessible
   for a certain values of the ruleType object?

Are there better alternatives?

I tend to go for the last one, because then an SNMP walk would
only show relevant information.

How have other MIB modules solved such a situation?

   Juergen
--
Juergen Quittek        quittek@ccrle.nec.de        Tel: +49 6221 90511-15
NEC Europe Ltd.,       Network Laboratories        Fax: +49 6221 90511-55
Kurfuersten-Anlage 36, 69115 Heidelberg, Germany   http://www.ccrle.nec.de