Re: [ppsp] New Version Notification for draft-ietf-ppsp-problem-statement-13.txt

Arno Bakker <arno@cs.vu.nl> Wed, 27 February 2013 14:08 UTC

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Date: Wed, 27 Feb 2013 15:08:35 +0100
From: Arno Bakker <arno@cs.vu.nl>
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Subject: Re: [ppsp] New Version Notification for draft-ietf-ppsp-problem-statement-13.txt
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On 26/02/2013 16:31, stefano previdi wrote:
>
> Please, have a look at the draft:
>   http://www.ietf.org/internet-drafts/draft-ietf-ppsp-problem-statement-13.txt
>
> and come back to the list with any comment.
>

Hi all

I have the following comments:

* PPSP.OAM.REQ-1: PPSP MUST be sufficiently configurable for 
installation and initial setup.

	I don't get the reference to "initial setup" there. I suggest
	to make the requirement "sufficiently configurable" (which is 	
	what we strived for with different chunk addressing, content
	protection methods) and state that the configuration should
	allow the proxy-based and end-client scenarios.

* PPSP.OAM.REQ-2: PPSP MUST implement a set of configuration 
parameters with default values.

	IMHO the descriptive text doesn't add anything and suggest it
	be removed.

* PPSP.OAM.REQ-3: PPSP MUST be capable of controlling traffic load to
existing networks.

	I suggest to rephrase this to "PPSP SHOULD allow steering by
	network-load management protocols." Current phrasing I find
	unclear and very restrictive with the MUST clause.

* PPSP.OAM.REQ-4: PPSP MUST support diagnostic operations.

	Typo: "correct operations" -> "correct operation"
	Typo: "*The* PPSP tracker should"
	Rephrase: "obtained chunks in due time" -> "whether it obtained
	chunks in time".

* PPSP.OAM.REQ-5: PPSP MUST facilitate achieving quality acceptable to
streaming application.

	I have problems with the last paragraph about scalable
	streaming. To me, it suggests scalable streaming should be
	supported. I suggest to rephrase to "PPSP implementations MAY
	use techniques such as scalable streaming to handle bandwidth
	shortages without disrupting playback."
	
	Typo: "to streaming application" -> "to *the* streaming ..."	
	
* PPSP.OAM.REQ-6: PPSP MUST support remote management using
centralized server, i.e. PPSP tracker. A basic set of management
information MUST be implemented by PPSP tracker.

	The wording suggests a centralized design where all management
	operations are done via the tracker. This image is not correct
	IMHO. A tracker service can play an important role in managing
	a swarm. E.g. it can be used to control publication of a swarm,
	or to monitor the health of the swarm. Hence it should have a
	standard management interface that supports such functionality.
	This interface should take into account that the tracker
	*service* may be implemented by multiple *servers*. However,
	PPSP should also support tracker-less designs and should define
	a management interface for (farms of) PPSP seeders.

	I suggest to rephrase the requirement so that the tracker
	service and PPSP seeders should have a remote management
	interface. Current descriptive text should be tweaked to
	explain the unique position of the tracker (sees both clients
	and PPSP seeders).

* PPSP.OAM.REQ-9: PPSP MUST support accounting management when content
provider wants to charge clients for certain content.

	I suggest to change the "MUST" to a "MAY" or "SHOULD allow
	accounting management".

CU,
     Arno