RE: Genart last call review of draft-ietf-bmwg-vswitch-opnfv-03

Alissa and Warren,

After Warren's message, a few more replies in-line, below,

Al (for the co-authors)

-----Original Message-----
From: Warren Kumari [mailto:warren(_at_)kumari(_dot_)net]
Sent: Tuesday, June 06, 2017 4:29 PM
To: Dan Romascanu
Cc: MORTON, ALFRED C (AL); gen-art(_at_)ietf(_dot_)org; 
draft-ietf-bmwg-vswitch-
opnfv(_dot_)all(_at_)ietf(_dot_)org; ietf(_at_)ietf(_dot_)org; 
bmwg(_at_)ietf(_dot_)org
Subject: Re: Genart last call review of draft-ietf-bmwg-vswitch-opnfv-03

On Thu, May 11, 2017 at 2:52 PM, Dan Romascanu <dromasca(_at_)gmail(_dot_)com>
wrote:

Hi,

Please see in-line.

Regards,

Dan


On Thu, May 11, 2017 at 8:00 PM, MORTON, ALFRED C (AL)

<acmorton(_at_)att(_dot_)com>

wrote:


Hi Dan,
please see replies, [ACM], below.

-----Original Message-----
From: Dan Romascanu [mailto:dromasca(_at_)gmail(_dot_)com]
Sent: Thursday, May 11, 2017 7:06 AM
To: gen-art(_at_)ietf(_dot_)org
Cc: draft-ietf-bmwg-vswitch-opnfv(_dot_)all(_at_)ietf(_dot_)org; 
ietf(_at_)ietf(_dot_)org;
bmwg(_at_)ietf(_dot_)org; dromasca(_at_)gmail(_dot_)com
Subject: Genart last call review of draft-ietf-bmwg-vswitch-opnfv-


Reviewer: Dan Romascanu
Review result: Almost Ready

I am the assigned Gen-ART reviewer for this draft. The General Area
Review Team (Gen-ART) reviews all IETF documents being processed
by the IESG for the IETF Chair.  Please treat these comments just
like any other last call comments.

For more information, please see the FAQ at

<https://urldefense.proofpoint.com/v2/url?u=https->> >

3A__trac.ietf.org_trac_gen_wiki_GenArtfaq&d=DwICaQ&c=LFYZ-

o9_HUMeMTSQicvjIg&r=OfsSu8kTIltVyD1oL72cBw&m=NTVlLBN-
L3u9zGPHm_CNVcXW7_OGX8_18CtaAalZin0&s=2Hr-
dhKaDHIguY7W97z33RlKjqPDtmoYmM2-jWrbS-o&e= >.

Document: draft-ietf-bmwg-vswitch-opnfv-03
Reviewer: Dan Romascanu
Review Date: 2017-05-11
IETF LC End Date: 2017-05-15
IESG Telechat date: Not scheduled for a telechat

Summary:

Almost Ready.

This document describes describes the progress of the Open Platform
for NFV (OPNFV) project on virtual switch performance "VSPERF".

That

project reuses the BMWG framework and specifications to benchmark
virtual switches implemented in general-purpose hardware. Some
differences with the benchmarking of specialized HW platforms are
identified and they may become work items for BMWG in the future.

It's

a well written and clear document, but I have reservations about it
being published as an RFC, and I cannot find coverage for it in the

WG

charter. I also have concerns that parts of the methodology used by
OPNFV break the BMWG principles, especially repeatability and
'black-box', and this is not clear enough articulated in the

document.

[ACM]
Ok, let's address your specific issues, and come back to your
reservations.



Major issues:

1. It is not clear to me why this document needs to be published as

an

RFC. The introduction says: 'This memo describes the progress of

the

Open Platform for NFV (OPNFV) project on virtual switch performance
"VSPERF".  This project intends to build on the current and

completed

work of the Benchmarking Methodology Working Group in IETF, by
referencing existing literature.' Why should the WG and the IESG
invest resources in publishing this, why an I-D or an Independent
Stream RFC is not sufficient?

[ACM]
The WG considered and discussed this document over 3 revisions
and a year of time before reaching consensus to develop it further
as a chartered item, so this decision was not taken lightly.
See more below.

The WG charter says something about:
'VNF and Related Infrastructure Benchmarking: Benchmarking
Methodologies have reliably characterized many physical devices.

This

work item extends and enhances the methods to virtual network
functions (VNF) and their unique supporting infrastructure. A first
deliverable from this activity will be a document that considers

the

new benchmarking space to ensure that common issues are recognized
from the start, using background materials from industry and SDOs
(e.g., IETF, ETSI NFV).'. I do not believe that this document

covers

the intent of the charter, as it focused on one organization only.

[ACM]
I'm sorry, but here you are mistaken. The document that satisfied
the "first deliverable ... document that considers the new

benchmarking

space"
is: https://urldefense.proofpoint.com/v2/url?u=https-

3A__tools.ietf.org_html_draft-2Dietf-2Dbmwg-2Dvirtual-2Dnet-
2D05&d=DwIBaQ&c=LFYZ-
o9_HUMeMTSQicvjIg&r=OfsSu8kTIltVyD1oL72cBw&m=hoHWXv58ay3WgLc115XYrprVmF9
14zpiiGCA6MQknbs&s=_mgJOrDLK33Nz_s9OA4mSGcbkZAkQSLjPNJ5qDIEAu4&e=

titled: Considerations for Benchmarking Virtual Network Functions and
Their Infrastructure
which has been submitted to IESG and approved for publication.
Further, the current draft (draft-ietf-bmwg-vswitch-opnfv-03)
references the approved "Considerations" draft in Section 3
(as does almost every related Industry spec I'm aware of).

The BMWG Charter continues:
  Benchmarks for platform capacity and performance characteristics of
  virtual routers, switches, and related components will follow,

including

  comparisons between physical and virtual network functions. In many
cases,
  the traditional benchmarks should be applicable to VNFs, but the

lab

  set-ups, configurations, and measurement methods will likely need

to

  be revised or enhanced.

This draft constitutes one of several follow-on efforts, approaching
the problem exactly as we described in the last sentence above.


[Dan wrote]
How? What last sentence?

Is it:

'In many cases,
  the traditional benchmarks should be applicable to VNFs, but the lab
  set-ups, configurations, and measurement methods will likely need to
  be revised or enhanced.'

[ACM] Yes

How does this document approach this problem?

[ACM] 
Lab setups (mentioned in the sentence) are illustrated in Section 4.
https://tools.ietf.org/html/draft-ietf-bmwg-vswitch-opnfv-03#page-12

Configuration parameters (mentioned in the sentence) are listed in Section 3.3
https://tools.ietf.org/html/draft-ietf-bmwg-vswitch-opnfv-03#section-3.3

If there is a need to revise
or enhance existing BMWG work, what is needed is specific revisions of
documents. This informational document only documents work in one external
organization. I have reservations that this is a WG task to advance this
document, and of the IESG to approve it. Why can't it stand as an I-D until
the WG decides whatever work needs to be undertaken (if any) to meet the
OPNFV needs? Or if they with to have an RFC, why can't it be Independent
Stream?

Will the WG write similar documents for all (or several) other organizations
that implement VNFs one way or another? Should it?

[Warren wrote]
Apologies for the delay, which is my almost entirely fault.

From the Shepherds write-up:
"There has been a fair amount of work done on this draft, and progress
made on revisions, feedback, and comments. Several presentations have
been made in the room during IETF meetings, and followup and
discussion taken to the BMWG list. This draft is particularly useful,
given the popularity of VNF's within the industry."

I believe that there is value in the IETF publishing this as an
Informational document - the document provides useful information for
the Internet community (especially those folk benchmarking VNFs :-)).
The OPNFV virtual switch performance characterization work is very
closely related and relevant to the BMWG work, and I think that having
a collaboration type document (written fom the IETF viewpoint, and
informing IETF participants) is useful.
This *could* have been an Independent Stream doc, but it was discussed
and worked on in the WG, and so having it be a WG document feels much
more correct to me.

W


An aspect of Industry collaboration that we did not anticipate in the
BMWG Charter is our current interactions with Open Source Communities.
The current Charter was approved in June 2014, then OPNFV was founded
on September 30, 2014 [0] and the VSPERF Project was created on
Dec 16, 2014, so we did not anticipate extensive collaboration on
this and other benchmarking topics.

[Dan wrote]
2. In section 3 there 'repeatability' is mentioned, while
acknowledging that in a virtual environment there is no guarantee and
actually no way to know what other applications are being run.

[ACM]
See:
https://urldefense.proofpoint.com/v2/url?u=https-

3A__tools.ietf.org_html_draft-2Dietf-2Dbmwg-2Dvirtual-2Dnet-2D05-
23section-2D3.4&d=DwIBaQ&c=LFYZ-
o9_HUMeMTSQicvjIg&r=OfsSu8kTIltVyD1oL72cBw&m=hoHWXv58ay3WgLc115XYrprVmF9
14zpiiGCA6MQknbs&s=tKgYWpJU1JA2Ig-UrXD5ClUdXXD9WUVsvu3UcWv5Caw&e=


There are certainly ways to assess the current set of processes
at a particular time. The Software configuration parameters in
Section 3.3 are intended to capture this aspect as part of set-up.
At the same time, there will be challenges to assess the DUT
performance when resources are fully shared, and new testing
strategies will be needed:
https://urldefense.proofpoint.com/v2/url?u=https-

3A__tools.ietf.org_html_draft-2Dietf-2Dbmwg-2Dvirtual-2Dnet-2D05-
23section-2D3.3&d=DwIBaQ&c=LFYZ-
o9_HUMeMTSQicvjIg&r=OfsSu8kTIltVyD1oL72cBw&m=hoHWXv58ay3WgLc115XYrprVmF9
14zpiiGCA6MQknbs&s=eopW3xeia2lNEFJSCCl2Pb--5azWfReW5I7kchktg3Y&e=


[Dan wrote]

Measuring parameters as the ones listed in 3.3 provides just part of
the answer, and they are internal parameters to the SUT.

[ACM]
Yes, knowing the tested configuration is a critical pillar
supporting repeatability (these items are not measured, but configured),
and why we provided this section.
[Dan wrote]

Also, the
different deployment scenarios in section 4 require different
configurations for the SUT, thus breaking the 'black-box' principle.

[ACM]
Specifying DUT configuration does not break any part of the
black-box principle, which establishes that benchmark measurements
will be based on externally observable phenomena. See:
https://urldefense.proofpoint.com/v2/url?u=https-3A__tools.ietf.org_html_draft-2Dietf-2Dbmwg-2Dvirtual-2Dnet-2D05-23section-2D4.2&d=DwIBaQ&c=LFYZ-o9_HUMeMTSQicvjIg&r=OfsSu8kTIltVyD1oL72cBw&m=hoHWXv58ay3WgLc115XYrprVmF914zpiiGCA6MQknbs&s=QFaIozbOelJnOh204GJCLlxA2MRLnHlxQJNO7BZkcqU&e=

Previous BMWG RFCs have identified the critical configuration
parameters of the DUT, such as the number and type of
network interfaces, the arrangement of DUTs in a SUT, etc.


[Dan wrote]
I may have not been clear enough. The document talks about repeatability and
about comparing benchmarks with the ones of specialized HW implementations.
Then it goes into a long but still partial list of factors that can
influence the benchmarking, the majority of them depend on the HW and SW
measurements and parameters of the internal systems. How can this be
compared with a number of small and indeed externally observable
configuration parameters like the number and type of network interfaces.
This is several degrees of magnitude apart in complexity.

[ACM] These are predominantly configured parameters in Section 3.3.
Frankly, I don't see anything listed that is measured.

BMWG has often specified configuration parameters that
are not directly observable, such as the routing protocol 
configuration parameters in parts of 
https://tools.ietf.org/html/rfc6413#section-5
for example.

Everyone actually working this problem appreciates the difficulty
and increase of about 3 orders of magnitude in configuration 
complexity.  Nevertheless, this is the reality of networking
with general purpose computers, and we have to solve this problem
to benchmark the performance in a scientific way.

{Dan wrote]

I believe that there is a need for a more clear explanation of why BMWG
specifications are appropriate and how comparison can be made while
repeatability cannot be ensured, and measurements are dependent upon
parameters internal to the SUT.

[ACM]
I believe that draft-ietf-bmwg-virtual-net-05 already
indicates why the existing BMWG RFCs are a reasonable
starting place for NFV benchmarks, in part because
we want to measure the same benchmarks of physical
network functions in many cases. See
https://urldefense.proofpoint.com/v2/url?u=https-

3A__tools.ietf.org_html_draft-2Dietf-2Dbmwg-2Dvirtual-2Dnet-2D05-
23section-2D4.1&d=DwIBaQ&c=LFYZ-
o9_HUMeMTSQicvjIg&r=OfsSu8kTIltVyD1oL72cBw&m=hoHWXv58ay3WgLc115XYrprVmF9
14zpiiGCA6MQknbs&s=uiLI0WilNHRGx4QniJ_A7JFakbFuwaolWQPL6_cWOY4&e=


Repeatability is a goal of all experiments, and we understand
that there is more work to do in this regard, but what
we know now (documented in this draft) should
be a valuable contribution to the Industry.

[Dan wrote]
Measuring the same benchmarks is a good goal. I believe that the claim of
repeatability needs to be better argued.

[ACM] 
I disagree, the repeatability problem needs to be solved, 
and many of us are working on it.


Minor issues:

1. Some of the tests mentioned in Section 4 have no prior or in
progress work in the IETF: Control Path and Datapath Coupling

Tests,

Noisy Neighbour Tests, characterization of acceleration

technologies.

[ACM]
I'm sorry, but that's not an accurate portrayal of BMWG's literature.

https://urldefense.proofpoint.com/v2/url?u=https-

3A__tools.ietf.org_html_rfc6413&d=DwIBaQ&c=LFYZ-
o9_HUMeMTSQicvjIg&r=OfsSu8kTIltVyD1oL72cBw&m=hoHWXv58ay3WgLc115XYrprVmF9
14zpiiGCA6MQknbs&s=FfwuOuYcIFOsJXVrIH-r4q2JyOmLP8Wqt6_sjGDnPe4&e=
examined Control Plane/Dataplane

interactions, for example.

https://urldefense.proofpoint.com/v2/url?u=https-

3A__tools.ietf.org_html_draft-2Dietf-2Dbmwg-2Dvirtual-2Dnet-2D05-
23section-2D3.3&d=DwIBaQ&c=LFYZ-
o9_HUMeMTSQicvjIg&r=OfsSu8kTIltVyD1oL72cBw&m=hoHWXv58ay3WgLc115XYrprVmF9
14zpiiGCA6MQknbs&s=eopW3xeia2lNEFJSCCl2Pb--5azWfReW5I7kchktg3Y&e=

item 2 specifically included Noisy Neighbour among the new
testing strategies.

[Dan wrote]
Please provide references for each in text.

[ACM] 
I'm sorry, but these references were for you, and 
only to remind you of BMWG's scope of work.
The IGP benchmarking reference is not appropriate here, and 
the other BMWG draft has been sufficiently referenced earlier.


Every network interface with an ASIC is an example of acceleration,
one that we've characterized in physical network devices for years.


Yes, but we do not deal here with externally observable interfaces only, and
if the characterization of the acceleration technologies matters than you
need a way to express it (where can we find it in existing BMWG work? new
work?)

[ACM] 
I think you misunderstood my reply. The acceleration technologies
we're calling-out perform specific functions, such as de/encapsulation
or encryption/decryption. An external/black-box test should measure
performance improvements in a way that can be compared to systems
under test that do not have the benefit of acceleration.
So, like I said above, when router vendors added ASICs on interfaces,
it didn’t change the fundamental benchmarks, but the performance 
improved.

If new work is needed / proposed to be added for the BMWG scope and
framework it would be useful for BMWG to list these separately.


Nits/editorial comments:

1. What is called 'Deployment scenarios' from VS perspective in
Section 4 describe in fact different configurations of the SUT in

BMWG

terms. It seems better to separate this second part of section 4 in

separate section. If it belongs to an existing section it rather
belongs in 3 than in 4.

[ACM]
Section 3 is more about extending the configuration guidance
from
https://urldefense.proofpoint.com/v2/url?u=https-

3A__tools.ietf.org_html_draft-2Dietf-2Dbmwg-2Dvirtual-2Dnet-2D05-
23section-2D3.2&d=DwIBaQ&c=LFYZ-
o9_HUMeMTSQicvjIg&r=OfsSu8kTIltVyD1oL72cBw&m=hoHWXv58ay3WgLc115XYrprVmF9
14zpiiGCA6MQknbs&s=Lwt9SappgKQIl2xBbUX9xEWpUrt0QV41B43nSef0BxM&e=


Section 4 summarizes the VSPERF Level Test Design document,
of which these deployment scenarios are a key part.


[Dan wrote]
Yes, but this seams to belong to configurations of SUTs, even if they are
called 'Deployment scenarios' in OPNFV-speak, and they impact repeatibility.

[ACM] 
You can only compare the performance of different computer SUTs when they
implement the same vSwitch (and VMs) and deployment scenario.
Consistent onfiguration parameters and test setups are all important 
components of achieving repeatable results.



thanks for your comments; hopefully this detailed reply
will reduce your reservations about publication.

Al
(for the co-authors)

[0]
https://urldefense.proofpoint.com/v2/url?u=https-

3A__www.opnfv.org_announcements_2014_09_30_telecom-2Dindustry-2Dand-
2Dvendors-2Dunite-2Dto-2Dbuild-2Dcommon-2Dopen-2Dplatform-2Dto-
2Daccelerate-2Dnetwork-2Dfunctions-2Dvirtualization&d=DwIBaQ&c=LFYZ-
o9_HUMeMTSQicvjIg&r=OfsSu8kTIltVyD1oL72cBw&m=hoHWXv58ay3WgLc115XYrprVmF9
14zpiiGCA6MQknbs&s=uvGoI10jbVot1-EAjx0SCT0fy0RzEwTlWyW6DWre4IU&e=




--
I don't think the execution is relevant when it was obviously a bad
idea in the first place.
This is like putting rabid weasels in your pants, and later expressing
regret at having chosen those particular rabid weasels and that pair
of pants.
   ---maf