Subject: RE: [Adslmib] Profile indexing

From: "Michael Sneed" <[email-masked]>
Date: Thu, 21 Nov 2002 17:54:06 -0500

> >In the case of, say, ifIndex and ifName, this wouldn't be such a problem,
> >since they aren't readily alterable.  Neither would it be if the VDSL MIB
> >were at Proposed, since I would not be at liberty to alter the OID or 
>name.
> >But I think there are assumptions about the administrative (or possibly
> >system) context in your example that are not part of the standard.
>
>Sorry.  I made the assumption that if anyone attempted to implement the
>internet draft, they would have to substitute some number for 'xxxx' in
>
>     ::= { transmission xxxx }
>
>to build a test case.  I further assumed that a reader of this list would
>understand that until (if) the IANA assigned a branch in the transmission
>tree
>to the VDSL MIB, any number that appears in place of 'xxxx' would be solely
>for purposes of example.  I shall refrain from such in the future.  
>Readers:
>Please do not substitute arbitrary numbers for 'xxxx' unless you know what
>you
>are doing and understand that the number has no significance other than on
>your
>own computer.
>
>Consider, instead, in the context of the previous email:
>
>	1.3.6.1.4.1.13674.1.1.13.1.3    pesaPresetMemberSyncSource
>
>which is from an enterprise MIB I just finished.  Used solely as a
>rhetorical
>device, this example should be considered to have no significance outside
>this
>discussion.
>
>:)
>
>Bob Ray
>

Do you own the MIB source?  Or perhaps someone implemented an agent with a a 
different version, where:

1.3.6.1.4.1.13674.1.1.13.1.3    pesaSystemShutdownIfRead ;-)

Maybe these analogies are too abstract, and we should examine the 
assumptions more explicitly.  Consider the case of a generic DSL system.

A user wants to assign profile "Gold" to LineX.

What does a  management application have to do?

If we use integer indices, it must walk the profile-name column of the 
profile table at the agent, looking for a match with "Gold".  When it finds 
it, it can then use the associated integer index to assign the profile to 
LineX.  Depending on the size of the profile table, that could amount to 
getting a lot of data.  More than the difference between the size of an 
integer and reasonable length string.

If the application doesn't walk the table at the agent, then it must be 
relying on a locally cached version of the profile table to provide the   
mapping. (Good assumption?  Bad assumption?)  Maybe, because of local 
administrative rules, that is OK.  Or maybe someone using a craft interface 
management application moved the "Gold" profile from slot 2 to slot 6 in the 
profile table, and put "Paper" in slot 2.  (It is likely the craft interface 
does not preclude this, right?)

If we use the profile name "Gold" as the index, this cannot happen.

So having an application do the translation between string and integer is OK 
if 1) it is OK to do a table walk (which sort of blows the efficiency 
argument), or 2) there is a local cache at EVERY application which does not 
want to do a table walk, and the local cache can be assumed to be properly 
synchronized with the agent, either via technical magic or administrative 
structures.

My guess is that you are assuming 2).  But table walks, technical magic, and 
administrative structures are all a lot of work.  If that is OK with  
everyone, then integer indices are OK.

Regards,

Mike

_________________________________________________________________
MSN 8 with e-mail virus protection service: 2 months FREE* 
http://join.msn.com/?page=features/virus

_______________________________________________
Adslmib mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/adslmib

---

From: "Bob Ray" <[email-masked]>
Date: Mon, 25 Nov 2002 10:04:14 -0600

Are there any opinions from the group on this indexing issue?

Currently, there are three voices/votes:

a) Umberto Bonollo - keep it as is (numeric indices)
b) Mike Sneed - revert to strings
c) Bob Ray - keep it as is 

At the IETF meeting, Faye Ly voted to use strings, so
there is a sorta deadlock (2/2).

Randy?  Bert?  Opinions?

Bob Ray