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RE: irrelevant objects in a row


The MIDCOM WG is looking for a MIB that points at different types of
technology rules (firewall, NAT, etc.) A dispatch table with void
pointers makes a lot of sense for this. (or a table with a pointer to an
abstract object that can take any object derived from the abstract

You can use a RowPointer in a mib dispatch table to point into
supplemental tables with different types of rules. 


> -----Original Message-----
> From: Juergen Quittek [mailto:quittek@ccrle.nec.de] 
> Sent: Friday, September 26, 2003 9:31 PM
> To: mibs@ops.ietf.org
> Subject: irrelevant objects in a row
> 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