Subject: on <draft-ietf-ippm-owdp-00.txt>'s model

From: "Cole, Robert G (Bob), ALSVC" <[email-masked]>
Date: Mon, 11 Dec 2000 17:19:01 -0500

Stanislav,
Benjamin,
Matt,

I have a question regarding the model chosen in the
one way delay measurement protocol.  Basically, the model
chosen is more complete than I had anticipated (not that
this is good or bad).  I copy a figure from your draft
(below).  Your draft covers both the OWDP-Test and OWDP-Control
protocols.

       +----------------+              +------------------+
       | Session-Source |--OWDP-Test-->| Session-Receiver |
       +----------------+              +------------------+
              ^                                ^
              |                                |
              |                                |
              V                                |
       +----------------+<---------------------+
       |     Server     |<------------+
       +----------------+             |
              ^                       |
              |                       |
         OWDP-Control            OWDP-Control
              |                       |
              V                       V
       +----------------+     +-----------------+
       | Control-Client |     | Retrieve-Client |
       +----------------+     +-----------------+

An alternative (I think) is to define the OWDP-Test protocol
and to rely on the work in the RMONMIB WG to handle the
OWDP-Control protocol through SNMP and the current draft
MIBs being discussed therein.  (see figure below).

       +----------------+              +------------------+
       | Session-Source |--OWDP-Test-->| Session-Receiver |
       +----------------+              +------------------+
              ^                                ^
              |                                |
             SNMP                             SNMP
              |                                |
              V                                |
       +----------------+<---------------------+
       |SNMP Server Appl|
       +----------------+            

The drafts I refer to are:

<draft-kalbfleisch-sspmmib-01.txt>
<draft-ietf-rmonmib-apm-mib-02.txt>
<draft-ietf-rmonmib-tpm-mib-00.txt>

At a minimum, I would hope that your draft would be constructed
in such a way that it does not exclude the use of the later model
where one uses an SNMP application to configure the test source and sinks
and the measurements are run using the OWDP-Test protocol without
relying on the OWDP-Control protocol.

I would much appreciate hearing your thoughts on this later approach.

Thanks,
Bob

-----------------------------------------------------
Robert G. Cole
AT&T Labs, Network Design and Performance Analysis Dept.
Tel: (410) 939-8732 	FAX: (410) 939-8732 
Pager: (888) 858-PAGE, pin 127113
email: [email-masked]	URL: http://chapman.mt.att.com/

330 Saint Johns St., 2nd Floor
Havre de Grace, MD  21078
		USA

---

From: "Henk Uijterwaal (RIPE-NCC)" <[email-masked]>
Date: Tue, 12 Dec 2000 01:19:56 +0100 (CET)

Bob,

> An alternative (I think) is to define the OWDP-Test protocol and to
> rely on the work in the RMONMIB WG to handle the OWDP-Control protocol
> through SNMP and the current draft MIBs being discussed therein.  
> (see figure below).
> 

In this picture, which process is sitting where and what does SNMP-SA
exactly tell the SS and SR?  

My preference would be: 

SA sits at a control point
SS and SR are measurement nodes

SA tells SS to send measurement packets starting at t=x with some set
            of parameters.
SA tells SR to expect data from SS starting at t=x

SS tells SA what it has sent
SR tells SR what it has received.

SR combines the 2 to report delays

This also works to measure losses (count the number of packets at both
ends) and thus connectivity.

> At a minimum, I would hope that your draft would be constructed in
> such a way that it does not exclude the use of the later model where
> one uses an SNMP application to configure the test source and sinks

I think that there is a lot of mileage in this idea.  The feedback that I
get from our customers on our work (http://www.ripe.net/test-traffic), is
that they are interested in eventually integrating delay and loss
measurements in their existing monitoring systems, and not in a
stand-alone device.  If we come up with our own protocol, then I fear that
the next thing we have to do, is to write a wrapper around the OWDP setup
protocol in order to integrate it with SNMP.

Henk

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---

From: stanislav shalunov <[email-masked]>
Date: 11 Dec 2000 20:26:21 -0500

"Cole, Robert G (Bob), ALSVC" <[email-masked]> writes:

> Basically, the model chosen is more complete than I had anticipated
> (not that this is good or bad).
[...]
> MIBs being discussed therein.

Robert,

draft-ietf-ippm-owdp-00 defines both OWDP-Control and OWDP-Test, but
it's not anticipated that all hosts that speak OWDP-Test would
necessarily also speak OWDP-Control.

Additionally it should be mentioned that our draft doesn't specify
protocols used on the unlabeled links of the example setup figure (and
doesn't even discuss whether there should be a protocol on this links).
The task of Session-Sender and Session-Receiver configuration could be
accomplished in a number of different ways.

This could be SNMP.  This could be sending shell commands over an SSH
session.  This could be anything.

I suppose we should explicitly mention the possibility of using
OWDP-Test without OWDP-Control, which will be done in the next draft
revision.  This is a prose change only.

-- 
Stanislav Shalunov <[email-masked]>	Internet Engineer, Internet2

A large number of installed systems work by fiat.  That is, they work
by being declared to work.                             -- Anatol Holt

---

From: stanislav shalunov <[email-masked]>
Date: 11 Dec 2000 20:46:49 -0500

"Henk Uijterwaal (RIPE-NCC)" <[email-masked]> writes:

> If we come up with our own protocol, then I fear that the next thing
> we have to do, is to write a wrapper around the OWDP setup protocol
> in order to integrate it with SNMP.

Henk,

Since OWDP-Test and OWDP-Control are separable, I don't think there's
need to define a wrapper.

On the other hand, having OWDP-Control can be helpful in the scenario
of network monitoring system using SNMP for a single network.  Namely,
you could, e.g., have a single host in your domain that speaks
OWDP-Control and allow (subject to a policy) use of your network
monitoring nodes to send or receive test traffic to/from outside your
domain.

"Nuclear war can ruin your whole compile."          -- Karl Lehenbauer

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From: "Henk Uijterwaal (RIPE-NCC)" <[email-masked]>
Date: Tue, 12 Dec 2000 02:49:46 +0100 (CET)

Stanislav,

> session.  This could be anything.

If it can be anything, then I believe the draft should simply say "how the
sessions are configured, is not discussed in this draft" instead of
putting 1 specific solution in the draft with a footnote that one can use
something else as well.

Including a specific solution, IMHO, gives the mistaken impression that
this is somehow preferred over other solutions.  If you want to make
OWDP-control a protocol, put it another draft.

Henk

ps. Ben, Matt, Stanislav: are you here and can we meet to discuss this
draft by VOS sometime tomorrow?

---

From: "Henk Uijterwaal (RIPE-NCC)" <[email-masked]>
Date: Tue, 12 Dec 2000 02:59:32 +0100 (CET)

Stanislav,

> need to define a wrapper.

If your measurement device uses OWDP-control and mine SNMP, then in order
to set up a measurement session between the two, one will have to
translate OWDP to SNMP (or the other way around).

> of network monitoring system using SNMP for a single network.  
> Namely, you could, e.g., have a single host in your domain that speaks

I fail to see why we need an extra protocol for this: with SNMP, one can
tell this host just as well to start sending/receiving test-traffic
from/to other sites.  

Henk