Re: Doc[1] Charting Networks

[Glenn Mansfield <[e-mail]>]

Valdis

In essence your question is how we intend to represent the complexities of
charge, cost, traffic in the attributes of the objects. 

Good questions. I guess that the same question applies to the routing-policy 
attribute in the ipNetworkImageObject, too.

We have thought about it and concluded two things 
	1. The taxonomy of the charge/cost/traffic/routing policies should
	   be dealt with in detail and in a separate place (preferably by 
	   som other person ;-). Some work on Routing policy requirements 
	   are done. We are not aware of similar works in charge, cost, 
	   traffic. 
	  [The SoftPages  project itself ofcourse works on a very simple 
	   model of charge,cost & traffic- but we do not claim it to be
	   a general model. ( Waiting for someone to do some work in this 
	   direction ;-) ]
	2. In the proposed Directory model it is possible to take care of 
	   fairly complex semantics using 
		- appropriate syntax for attributes something like the tuple
		  they use for describing "policy terms" for routing
		- multiple values of the same attributes

I hope this answers your question.

cheers

glenn

 *****************************************************************
 * Glenn Mansfield                                               *
 * AIC Systems Laboratory                Phone : [phone] *
 * 6-6-3, Minami Yoshinari               Fax   : [phone] *
 * Sendai, Japan. 989-32                 e-mail: [e-mail] *
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>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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   >>Date: Mon, 09 Nov 92 14:51:29 EST
   >>From: Valdis Kletnieks <[e-mail]>
   >>Organization: Virginia Polytechnic Institute
   >>Subject: Re: Doc[1] Charting Networks
   >>To: Glenn Mansfield <[e-mail]>jp>, [e-mail]
   >>Cc: [e-mail], [e-mail], [e-mail]
   >>In-Reply-To: <[e-mail]>
   >>Message-Id: <[e-mail]>
   >>Status: R
   >>
   >>On Mon, 9 Nov 92 11:20:08 JST you said:
   >>> 5.2.3 Line
   >> ...
   >>> line OBJECT CLASS
   >> ...
   >>>   charge         :: numericStringSyntax,
   >>>        /* to be paid by user for transmission
   >>>             of data (per packet/byte/time...)  */
   >>
   >>It's  crucial that  the units  be  carried along  here. There  is a  big
   >>difference  between $2000/month  and $2000/packet.  Of course,  here you
   >>can make a guess that $2000US is a  "per month" charge - but what if the
   >>value is $2.50 - is this a "weekly" or a "per megabyte" charge?
   >>
   >>Also, a numeric value alone isnt much  use. If the object described is a
   >>T-1 link running  from an ENSS in Ithaca, NY  to Montpelier, France, are
   >>the  units  US dollars  or  francs?  And  what effect  do  international
   >>currency fluctuations have?
   >>
   >>>   cost      :: numericStringSyntax,
   >>>        /* to be paid to service provider for use of line
   >>>             (per month, traffic...)  */
   >>Same as above..
   >>
   >>>   traffic        :: numericStringSyntax
   >>>        /* (average) use in percent of nominal bandwidth */
   >>>         }
   >>
   >>What timeframe  is this "average" taken  over? And how do  you deal with
   >>objects  with widely  varying loads  over time/space?  For instance,  we
   >>have  a  large (about  800  node)  Ethernet-based network  that  employs
   >>bridges  for traffic  filtering. Some  segments (for  instance, over  in
   >>McBryde Hall,  where both Math and  CS are located) run  quite congested
   >>during  the day,  but  are essentially  idle at  night,  except for  the
   >>occasional NTP packet.  Other segments sit at a pretty  constant 15% the
   >>entire day.
   >>
   >>Also, remember that  for many media types, nominal  bandwidth has little
   >>relationship to actual  capacity. Note that both  the Ethernet collision
   >>detection/avoidance and  most routers perform somewhat  differently when
   >>presented with a few 8K NFS  packets fragmented into 1500 byte segments,
   >>an  several  zillion  telnet  packets  with  one  character  of  data  a
   >>packet....
   >>
   >>
   >>                                  Valdis Kletnieks
   >>                                  Computer Systems Engineer
   >>                                  Virginia Polytechnic Institute
   >>