Subject: Re: open issues in agentX MIB

From: "Smitha Gudur" <[email-masked]>
Date: Fri, 31 Jul 1998 14:45:24 PDT

Hi, Mike,

There is relationship between sessionID defined in RFC2257 and
the agentxSessionIndex.

Current description for agentxSessionIndex includes:

"Index values assigned for a given registration are constant for the 
lifetime of this table."

is inappropriate and needs to be removed.  

The other part of the description is consistent with the RFC.

"A unique index for the subagent session. Note that if a
subagent's session with the master agent is closed for
any reason its index should not be re-used, therefore,
the values of agentxSessionIndex may not be contiguous and
will generally not be the same for the same subagent
across multiple sessions."

thanks for the inputs.

regards
smitha

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>If there is a relationship between sessionID as defined in RFC2257and
>agentxSessionIndex then the relationship needs to be clarified and the
>description of agentxSessionIndex made consistent with the definition 
in
>the RFC. (See sections 6.1, 6.2.16, 7.1.1(3))
>
>MikeT
>
>

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---

From: Bob Natale <[email-masked]>
Date: Fri, 31 Jul 1998 18:32:19 -0400

>At 7/31/98 02:45 PM, Smitha Gudur wrote:

Hi Smitha,

>There is relationship between sessionID defined in RFC2257 and

Logically, that's true.  The value used for agentxSessionIndex
to identify the session should be the same as that used for
the SessionID as given by the master agent to the subagent.
The problem Mike alludes to here derives from the "should not
be re-used" semantics used for agentxSessionIndex in the MIB
but which are missing from the RFC references to SessionID.

I would argue that the RFC text should be tightened in this
respect, to stipulate non-reuse; but it is clear that a
reasonable argument can be made for not stipulating it and
leaving it up to the implementation.

In my view, however, management apps will be able to use
the MIB better to monitor the overall AgentX system if
the non-reuse semantics of agentxSessionIndex are carried
over to SessionID.  This value, via agentxSessionIndex,
is critical to all three of the tables currently defined
in the MIB [btw, we should all be reading from the -02.txt
version of the MIB document, dated April 14, 1998, at this
point]:

	agentxConnectionTable
	agentxSessionTable
	agentxRegistrationTable

In thinking through the relationships, it seems that we
need to add agentxConnIndex to the AgentxSessionEntry and 
agentxSessionIndex to the AgentxRegistrationEntry.  In this
way, each registration entry can point to the session in
which it lives and each session can point to the connection
in which it lives.

[Note to Smitha and Lauren here in particular:]
The rationale and the consequent OBJECT-TYPE macros
should be obvious (I think), but if not let me know.

>"Index values assigned for a given registration are constant
>for the lifetime of this table."
>

Right.

>The other part of the description is consistent with the RFC.

That's the debatable part.

>thanks for the inputs.

Likewise.

Cordially,

BobN
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---

From: Mike Thatcher <[email-masked]>
Date: Mon, 03 Aug 1998 11:19:18 -0700

> the SessionID as given by the master agent to the subagent.

Now this may have been discussed before, and if so could you review
the reasoning.  But if the value for for agentxSessionIndex is
expected to be the value of the SessionID, why don't you call it
agentxSessionID?  Otherwise  people like me may read the MIB and since
there is no reference to sessionID, could implement this as a unique
value assigned by the MIB implementation with no reference to
sessionID at all.

MikeT

---

From: Bob Natale <[email-masked]>
Date: Mon, 03 Aug 1998 14:47:17 -0400

>At 8/3/98 11:19 AM, Mike Thatcher wrote:

Hi Mike,

>agentxSessionID?  Otherwise  people like me may read the MIB and
>since there is no reference to sessionID, could implement this as
>a unique value assigned by the MIB implementation with no reference
>to sessionID at all.

Yes, you are exactly right...and that is, in part, why the
current process of normalizing the MIB doc wrt the protocol
doc is under way.  At this stage, I'd say it's not a totally
unidirectional process--i.e., we *could* identify some useful
MIB construct that might need supporting text in the protocol
document...but I can't see anything like that on the horizon.

I suppose that Smitha and/or Maria was/were just trying to
be internally self-consistent with naming conventions in an
earlier rev of the MIB and the wording stuck...'til now.
I agree with you that it would be wise to use identical
terminology--driven by that used in RFC 2257--in every
place possible in the MIB document (ditto in any eventual
API document that the WG might elect to work on in the
future).

>MikeT

[Btw, Mike, mail I send to your Cisco address keeps
bouncing back to me...I assume you're getting this
via the AgentX list ok...and your rahul.net address
seems to work for me...?]

Cordially,

BobN
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---

From: Mike Daniele <[email-masked]>
Date: Mon, 03 Aug 98 15:42:40 -0400

Hi,

>API document that the WG might elect to work on in the

It's not just the name of the object, right?
The real issue is, is agentxSessionIndex == h.SessionID?
We need to say so in the MIB spec one way or the other.
 
I asked a while ago

> 5) Is the value of agentxSessionId the same as the sessionID field
>    within the protocol?

And Randy replied

>The value of agentxSessionIndex should map to the value of h.sessionID 
>used for a given session.  The non-reuse requirements for the MIB index
>are stricter than those for the protocol field.  (Aside: why does the
>protocol require that h.sessionID be given values unique across all of
>a master agent's transports?  The logical requirement for uniqueness
>ends at the level of a transport connection.)

Since we're moving toward refining h.SessionID to not be reused by the 
master within the realm of 32-bit rollover, it seems like the non-reuse 
requirements of the 2 are identical.

Given that, it seems beneficial to me to use an index with semantic
meaning.  Make them the same value.
 
I think the name agentxSessionIndex is fine.  

I think the description should state this value must equal h.SessionID for
this session.

Note, currently it's legal to use a SessionID of 0.  If we're going to
make agentxSessionIndex == h.SessionID, we may want to stipulate
SessionIDs start at 1.

Mike

---

From: Bob Natale <[email-masked]>
Date: Mon, 03 Aug 1998 16:35:28 -0400

>At 8/3/98 03:42 PM, Mike Daniele wrote:

Hi Mike,

<...>

Right.

>requirements of the 2 are identical.

Right.  Maintaining uniqueness of h.SessionID across all active
sessions--irrespective of transport connections--is simpler than
maintaining uniqueness within transport connections and yields
more payoff to boot (e.g., simplifying registration relationships
and possibly traffic/error reporting).

>meaning.  Make them the same value.

Yes.

>I think the name agentxSessionIndex is fine.  

Ok by me.

>I think the description should state this value must equal h.SessionID
>for this session.

Yes.

>Note, currently it's legal to use a SessionID of 0.  If we're going
>to make agentxSessionIndex == h.SessionID, we may want to stipulate
>SessionIDs start at 1.

I favor this stipulation too.

Cordially,

BobN
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