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

[zhangyunfei <[e-mail]>]

Hi Arno and all, (Speaking as the co-author)
    Thanks for the comments and Ning will update the requirements part in next week.

BR
yunfei




zhangyunfei

From: Arno Bakker
Date: 2013-02-27 22:08
To: [e-mail]
Subject: Re: [ppsp] New Version Notification for draft-ietf-ppsp-problem-statement-13.txt
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

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