Subject: [Diffserv] New diffserv MIB (rev 13) and MIB Compliance

From: "Wijnen, Bert (Bert)" <[email-masked]>
Date: Sat, 15 Sep 2001 17:10:09 +0200

You may have noticed that Fred has posted a new diffserv mib.
It has (at my suggestion) been updated to contain two compliance
statements. Fred has writes:

   Some would like them named

                diffServMIBReadWriteCompliance
       and     diffServMIBReadOnlyCompliance

   and some would like them named

                diffServMIBFullCompliance
       and     diffServMIBCompliance

I am among the some (actually I proposed) who think that they 
should be named:

    diffServMIBFullCompliance
    diffServMIBReadOnlyCompliance

My reasoning/argumentation/thinking is that:

- This MIB has got a lot of attention so that it can also be
  used for configuration (with SNMP) of diffserv capable devices.
  The Diffserv WG and MIB authors have worked with the SNMPCONF
  and RAP WG people to also look at it from the perspective of
  allowing configuration on a network-wide basis, or for
  policy-based configuration.

- I have proposed a limited set of values for RowStatus (i.e. 
  no need to support createAndWait and notInService, so that
  we reduce the complexity at the agent side. So that means that
  (for this MIB), when a row/entry is created, one MUST send
  all the values for all columnar objects for the whole row
  (as an aside, for this MIB such SNMP SET PDUs will all fit
   even in a 484 octet SNMP PDU). This is a first step to try 
  and alleviate some concerns about SNMP SET complexity.

- We traditionally have used only one compliance statement that
  had the form of the diffServMIBReadOnly compliance. We always
  named it just something like diffServMIBCompliance. This means
  that vendors who implement the MIB in read-only mode claim the
  same compliance as those who implement in read-write mode.
  Also for customers, when they ask a vendor for MIB compliance,
  this means that they need to explicitly state if they want them
  to do read-only or read-write coimpliance. So it seems better
  to actually do 2 compliance statements. 

- The ReadOnly compliance allows people to implement read-only 
  but also read-write.

- The ReadWrite (or in my view better the Full) compliance requires
  people to implement read-write, so that you can configure with SNMP.

- ReadWrite compliance of course expresses what the compliance means
  namely that you implement in read-write mode as opposed to just
  read-only mode.

- But to be fair, the ReadOnly compliance is really only a partial
  implementation of the functionality of the MIB.
  I figured I would not want to give that a negative name of something
  like diffServMibPartialCompliance. 

- Instead I proposed to give a ReadWrite implementation a positive
  spin using a name of diffServMIBFullCompliance. And to be fair again,
  a read-write implementation is indeed a FULL compliance with ALL the
  functionality that the MIB provides.

- And it is also fair to say, that I have a little hope that by the
  use of FullCompliance, we might encourage people just a tidbit to
  indeed implement and use the full functionality of the MIB. 
  Of course every customer and vendor will evaluate the cost/benefit
  ratio of each compliance before they ask for it or implement it.
  That is, in the end the market decides.

- Let me also add that we already have examples of the use of
  a FULL compliance with other partial compliances, like in
  RFC2573, where we do have on snmpNotifyFullCompliance
  and a few other partial compliance statements.
  Other examples can be found in RFC1628, RFC2594, RFC2789 and
  RFC2837. So it is not new to show people what is needed for
  FULL compliance.

Anyway, as Fred asked, if you have an opinion on this, it would be 
good to express this on this mailing list.

Bert 

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---

From: Brian E Carpenter <[email-masked]>
Date: Mon, 17 Sep 2001 10:32:31 -0500

"Wijnen, Bert (Bert)" wrote:
...
>     diffServMIBReadOnlyCompliance

This looks like a compromise with several people supporting it.

If this is *unacceptable* to you please say so *now*.

   Brian Carpenter
   diffserv co-chair