Subject: [PCN] Terminology

From: Michael Menth <[email-masked]>
Date: Sun, 09 Mar 2008 13:39:49 +0100

Hi Phil and others,

I have some improvements for the high level description of PCN including 
some nomenclature. I suggest to rename the expressions

   o  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
      a marking behaviour that determines whether a packet should be
      PCN-marked with a first encoding.

   o  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 a marking behaviour that determines whether a packet should be
      PCN-marked with a second encoding.

   o  Admissible Rate (AR): a reference rate configured for each link in 
the
      PCN-domain. It's the rate up to which admission control should accept
      new flows.

   o  Supportable Rate (SR): a reference rate configured for each link 
in the
      PCN-domain. It's the rate down to which flow termination should
      terminate already admitted flows if they cause overload. SR does not
      need to be given explicitly but also implicitly by SR=u*AR with 
the same
      value u for all links in the network.

The new naming is very general and applicable to any existing proposal. 
It helps to make text more readable. The new expressions also help to 
qualify the types of pre-congestion and overload on a link in an 
intuitive way which is also easy to remember.

Types of pre-congestion on a link:
* No pre-congestion (NPC): PCN rate <= AR
* AR-pre-congestion (ARPC): AR < PCN rate <= SR
* SR-pre-congestion (SRPC): SR < PCN rate

Types of overload on a link:
* no overload (PCN rate <= AR)
* AR-overload = PCN rate - AR (per link)
* SR-overload = PCN rate - SR (per link)

I have summarized the general PCN idea using this nomenclature on two 
PPT slides:
http://www3.informatik.uni-wuerzburg.de/staff/menth/Publications/PCN-Description.ppt

In contrast, the naming of the packet marking depends on the specific 
proposals and cannot be streamlined similarly as the semantics of the 
markings depends both on the metering and marking method connected with 
the AR and SR thresholds.
* CL: unmarked, admission-marked (AM), termination-marked (TM)
* 3sm: no-pre-congestion (NP), admission-stop (AS), excess-traffic (ET)
* SM: unmarked, admission marked (AM)
* LC-PCN: unmarked, "PCN_Marked", "Affected_Marked"
 From my point of view, it makes sense to adopt the new nomenclature 
concerning the general PCN idea in the architecture draft, but it 
currently does not make sense to harmonize the naming of the marking.

I am already in Philadelphia and look forward to see you guys again at 
the welcome reception tonight.

Regards,

    Michael

-- 
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

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---

From: <[email-masked]>
Date: Mon, 10 Mar 2008 18:00:36 -0000

michael
 
i'll think about this, thanks - but quite reulctant to re-open discussion about terminology unless we really really need to, as we've already proven that it rat-holes. lars made a comment in his review about one section needing some re-phrasing in order to elegantly talk about single marking, so will think about that at the same time. 
 
phil

________________________________

From: Michael Menth [mailto:[email-masked]]
Sent: Sun 09/03/2008 12:39
To: Eardley,PL,Philip,CXR9 R
Cc: pcn
Subject: Terminology

Hi Phil and others,

Regards,

    Michael