Subject: [PCN] PCN terminology

From: <[email-masked]>
Date: Fri, 3 Aug 2007 18:22:53 +0100

Hi,

I'm starting to do the mods in order to create
draft-ietf-pcn-architecture-00, based on
draft-eardley-pcn-architecture-00.

One of the things is to adapt the PCN terminology. The consensus at the
WG in Chicago was to move to names that are more 'neutral' and to use
names for marking that reflect how the marking is done (rather than what
it is trying to achieve). I think that PCN-upper-rate & PCN-lower-rate,
and threshold-marking and excess-rate-marking were mentioned. 

A copy and paste of the definitions isn't quite possible, are the
following are OK? I also tried to take account of Bob's review comment
(25 july on the list) that we shouldn't use "rate" in the definitions
loosely. 

*        PCN-lower-rate: a reference rate configured for each link in
the PCN-domain, which is lower than the PCN-upper-rate. It is used by an
algorithm that determines whether a packet should be PCN-marked with a
first encoding

*        PCN-upper-rate: a reference rate configured for each link in
the PCN-domain, which is higher than the PCN-lower-rate. It is used by
an algorithm that determines whether a packet should be PCN-marked with
a second encoding. 

*        Threshold-marking: a PCN-marking algorithm such that all
PCN-traffic is marked if the PCN-traffic exceeds a particular rate
(either the PCN-lower-rate or PCN-upper-rate). NOTE: The definition
reflects the intent of the algorithm rather than its instantaneous
behaviour, since the rate measured at a particular moment depends on the
algorithm, its implementation and the traffic's variance as well as its
rate

*        Excess-rate-marking: a PCN-marking algorithm such that the
amount of PCN-traffic that is PCN-marked is equal to the amount that
exceeds a particular rate (either the PCN-lower-rate or PCN-upper-rate).
NOTE: The definition reflects the intent of the algorithm rather than
its instantaneous behaviour, since the rate measured at a particular
moment depends on the algorithm, its implementation and the traffic's
variance as well as its rate

*        PCN-marking: either threshold-marking or excess-rate-marking

{if necessary we can define: PCN-lower-rate-marking and
PCN-upper-rate-marking}

 I'll remove the term ECN-marking, which is unnecessary.

 What do you reckon?

Best wishes,

phil

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---

From: Michael Menth <[email-masked]>
Date: Tue, 07 Aug 2007 00:13:06 +0200

Hi Phil and others,

as far as I can remember, we were about to discuss on the list the use of
1) "(configured-)admission rate" vs. "admissible rate" for the PCN lower 
threshold.
2) "admission marking" vs. "admission-stop marking" for the marking 
associated with the PCN lower threshold.
which are very similar and it shouldn't be a problem to find a consensus 
for one of them.

As PCN is used for admission control, and as all proposals I am aware 
of, use the admissible rate threshold and the associated marking to 
support admission control, I don't see the need for neutral names like 
"lower PCN threshold". I don't find them good because they hide the 
purpose the defined mechanism and make explanations more difficult. I 
was unable to attend the meeting in Chicago, so I miss the reasons for 
neutral instead of mnemonic names. What's the motivation behind this, in 
particular for the lower PCN threshold?

Regards,

Michael

[email-masked] wrote:
>
> Hi,
>
> I’m starting to do the mods in order to create 
> One of the things is to adapt the PCN terminology. The consensus at 
> the WG in Chicago was to move to names that are more ‘neutral’ and to 
> use names for marking that reflect how the marking is done (rather 
> than what it is trying to achieve). I think that PCN-upper-rate & 
> PCN-lower-rate, and threshold-marking and excess-rate-marking were 
> mentioned.
>
> A copy and paste of the definitions isn’t quite possible, are the 
> following are OK? I also tried to take account of Bob’s review comment 
> (25 july on the list) that we shouldn’t use “rate” in the definitions 
> loosely.
>
> · PCN-lower-rate: a reference rate configured for each link in the 
> PCN-domain, which is lower than the PCN-upper-rate. It is used by an 
> · PCN-upper-rate: a reference rate configured for each link in the 
> PCN-domain, which is higher than the PCN-lower-rate. It is used by an 
> second encoding.
> · Threshold-marking: a PCN-marking algorithm such that all PCN-traffic 
> is marked if the PCN-traffic exceeds a particular rate (either the 
> PCN-lower-rate or PCN-upper-rate). NOTE: The definition reflects the 
> intent of the algorithm rather than its instantaneous behaviour, since 
> the rate measured at a particular moment depends on the algorithm, its 
> implementation and the traffic's variance as well as its rate
>
> · Excess-rate-marking: a PCN-marking algorithm such that the amount of 
> PCN-traffic that is PCN-marked is equal to the amount that exceeds a 
> particular rate (either the PCN-lower-rate or PCN-upper-rate). NOTE: 
> The definition reflects the intent of the algorithm rather than its 
> instantaneous behaviour, since the rate measured at a particular 
> · PCN-marking: either threshold-marking or excess-rate-marking
>
> I’ll remove the term ECN-marking, which is unnecessary.
>
> What do you reckon?
>
> Best wishes,
>
> phil
>
> ------------------------------------------------------------------------
>

-- 
Dr. Michael Menth, Assistant Professor
University of Wuerzburg, Institute of Computer Science
Am Hubland, D-97074 Wuerzburg, Germany, room B206
phone: (+49)-931/888-6644, fax: (+49)-931/888-6632
mailto:[email-masked]
http://www3.informatik.uni-wuerzburg.de/research/ngn

---

From: <[email-masked]>
Date: Tue, 7 Aug 2007 08:37:57 +0100

- threshold-marking & excess-rate-marking: the general feeling was that
the 'marking' names shouldn't reflect the (supposed) purpose to which
receipt of the markings would be put, but rather should reflect the
characteristic of the algorithm used to set the marking (how does it
work?)
- PCN-lower-rate and PCN-upper-rate: similarly, the general feeling was
that the names for the configured rates shouldn't reflect the (supposed)
purpose to which the rates are related. For example, with the single
marking proposal, a single rate drives both flow admission ctrl and
termination; in the future, markings associated with the PCN-upper-rate
might drive flow adaptation as well as flow termination, and perhaps
something similar could be imagined in the future for markings
associated with the PCN-lower-rate (eg priority of the admitted traffic)

well that was my take on the meeting's discussion/consensus!

Best wishes,
phil

> -----Original Message-----
> From: Michael Menth [mailto:[email-masked]]
> Sent: 06 August 2007 23:13
> To: Eardley,PL,Philip,CXR9 R
> Cc: [email-masked]
> Subject: Re: [PCN] PCN terminology
> 
> Hi Phil and others,
> 
> > the WG in Chicago was to move to names that are more 'neutral' and
to
> > * PCN-lower-rate: a reference rate configured for each link in the
> > * PCN-upper-rate: a reference rate configured for each link in the
PCN-traffic
> > * Excess-rate-marking: a PCN-marking algorithm such that the amount
of