Subject: [bmwg] RE: Objections to Applicability statement draft: OSPF convergence benchmarking

From: "Manral, Vishwas" <[email-masked]>
Date: Sat, 15 Feb 2003 06:14:25 -0500

The link to the paper: -
 
http://www.research.att.com/~albert/papers/sigcom-imw01/mes-ws01-paper.pdf
<http://www.research.att.com/~albert/papers/sigcom-imw01/mes-ws01-paper.pdf>

Thanks,
Vishwas

-----Original Message-----
From: Manral, Vishwas 
Sent: Saturday, February 15, 2003 2:17 PM
To: 'Scott Poretsky'; [email-masked]
Subject: Objections to Applicability statement draft: OSPF convergence
benchmarking

Hi Scott,
 
You have stated the same points of white-box benchmarks again for the
methodology draft, which i have replied in the other mail.
 
The factors we rely on have been stated clearly in the OSPF RFC2328. I guess
you are talking about section 6 for all the "implementation" related
information. Also measurements were taken on the CIsco box, using the same
methodology, please check the document I have been relating to in the last
two mails.
 
The new point you have stated is the abscence of traffic. Our draft does not
prevent anyone from using data traffic to get more measurements(just that
those measuremnts wil have the effect of data traffic, if we can have
similar data traffic for all measurements we can easily get comparative
measurements(though absolute measurements would be a bit wrong). We can
always use data traffic, check bullet 2, Section 5, of the applicability
draft for that.
 
Actually thinking of it, i guess we can refine the applicability statement
with your help.;-) Any further comments will be helpful.
 
Thanks,
Vishwas

-----Original Message-----
From: Scott Poretsky [mailto:[email-masked]]
Sent: Friday, February 14, 2003 11:28 PM
To: [email-masked] <mailto:[email-masked]> 
Subject: Re: Fwd: Re: [bmwg] WG Last Call: OSPF convergence benchmarking

Folks,

While I think that IGP Convergence testing is very worthwhile work for the
BMWG to undertake, these drafts do not address IGP Convergence.  These
proposed drafts focus on LSA propagation benchmarking.  Due to the extreme
interest in industry for IGP convergence measurements, I was working on IGP
Convergence terminology and benchmarking methodology drafts when these
proposed drafts were submitted.  I have provided the IGP Convergence drafts
to Kevin and they should soon be posted.  My comments to the proposed LSA
Propagation benchmarking drafts are below.  

Scott
----------------------------------------------------------------------------
-
Terminology
Internal Measurements and External Measurements are already defined as White
Box and Black Box.

Point-to-Point, Broadcast, SPF, Hello Interval, and Router Dead Interval are
already defined in IETF RFCs

Incremental-SPF is a vendor-specific feature.

Convergence is stated as " A network is termed to be converged when all of
the devices within the network have a loop free path to each possible
destination. "   The definition is then modified for  a single DUT as follow
"Since we are not testing network convergence, but performance for a
particular device within a network, however, this definition needs to be
narrowed somewhat to fit within a single device view.  In this case,
convergence will mean the point in time when the DUT has performed all
actions needed to react to the change in topology represented by the test
condition ".   This must include updating the FIB and hardware as externally
verified with data traffic.  This draft contradicts its own definition by
verifying convergence through measurement of only LSA propagation.  In fact,
updating the FIB is explicitly excluded from measurement.

Methodology
Section 5. Overview and Scope
Control Plane measurements are not convergence measurements.  Convergence is
benchmarked by time to reroute traffic.

Section 6. Test Conditions
Bullet 2  It cannot be assumed that there is zero delay to execute the SPF
or  LSA processing.  Reference [5] actually _recommends_ router vendors
implement zero delay to achieve low convergence.  The benchmarking
methodology should allow convergence measurements to be made regardless of
implementation.

Bullet 3  Data traffic is actually required to make a deterministic
measurement of route convergence.
Unlisted: Number of IGP routes is a critical parameter for convergence time.

Sections 7. through 9.
The biggest problem with the methodology is that not all components for
convergence time are measured.  Focus is on LSA Processing, which is only 1
of 4 major components.

Route change due to cost or next-hop change is not considered.  This is the
most common reason for route convergence.

Well -defined Convergence methodology can be applied to ISIS or OSPF.  The
Link-State IGP does not matter.  In fact the methodology should be able for
use to benchmark one IGP against the other given the same DUT.

All procedures meet one or more of the following flaws:
White box measurements are part of the procedure.
Time to install route (update FIB), update hardware, and reroute traffic are
not considered.
Test case is Implementation-specific.
Test case has nothing to do with convergence - more OSPF performance test. 

Applicability
The applicability document explains that convergence testing is needed using
1. White box benchmarks
2. DUT intrusive measurements
3. Knowledge of DUT implementation
4. Absence of traffic results in impractical benchmarks.  Convergence time
is benchmarked by traffic loss.
1 through 3 violate basic test methodology requirements.  4 makes invalid
convergence tests.
This work is less about convergence benchmarking and more about LSA
propagation benchmarking.

---

From: "Manral, Vishwas" <[email-masked]>
Date: Sat, 15 Feb 2003 06:14:25 -0500

The link to the paper: -

Thanks,
Vishwas

-----Original Message-----
From: Manral, Vishwas 
Sent: Saturday, February 15, 2003 2:17 PM
To: 'Scott Poretsky'; [email-masked]
Subject: Objections to Applicability statement draft: OSPF convergence
benchmarking

Hi Scott,

 

Thanks,
Vishwas

-----Original Message-----
From: Scott Poretsky [mailto:[email-masked]]
Sent: Friday, February 14, 2003 11:28 PM
To: [email-masked] <mailto:[email-masked]> 
Subject: Re: Fwd: Re: [bmwg] WG Last Call: OSPF convergence benchmarking

Folks,

Scott

Methodology

Sections 7. through 9.

Applicability