Re: ifNumber and its ilk considered harmful

[Andy Bierman <abierman@cisco.com>]

At 01:28 PM 2/7/2003 -0800, Mike MacFaden wrote:
>On Fri, Feb 07, 2003 at 12:21:42PM -0800, C. M. Heard wrote:
>>> Have any recent reviews disapproved of using scalars like ifNumber?
>>
>>Not from me, certainly.  Indeed, I agree that the FIB counter
>>inetCidrROuteNumber should be re-instated into 2096-update,
>>and said so in my recent comments on the ipv6 list.  The
>>inetCidrRouteTable can be HUGE (100Ks of entries), and it's
>>obviously not efficient (and probably not even feasible) for
>>a management station to count the number of entries by
>>retrieving the whole table.
>
>Indeed.
>
>An alternative I proposed to Margaret was to follow the model
>used in rfc2021 for HUGE tables: namely using two counters
>to track inserts and deletes. 

This doesn't make any sense.  If an implementation utilizing
subagents can support two counters (inserts and deletes) then
it can easily support a single gauge like ifNumber.  It just
implements ifNumber internally as two counters and returns
inserts - deletes when asked for ifNumber.

Andy



>Another thing not considered in Margaret's latest 2096 replacement
>draft is that both rfc2096 and its successor are both active 
>in the same agent at the same time. 
>
>So I think ipCidrRouteNumber will apply
>to both the existing and replacement table regardless, 
>it will just be a count of the ipv4 routes...
> 
>Mike