Subject: [ppsp] problem statement of ppsp(new version)

From: [email-masked]
Date: Tue, 4 Nov 2008 17:52:54 +0800

Dear all,
   Attached is the updated problem statement of ppsp.Comments and suggestions are highly welcome.

_______________________________________________
ppsp mailing list
[email-masked]
https://www.ietf.org/mailman/listinfo/ppsp

---

From: "Hui Zhang" <[email-masked]>
Date: Tue, 4 Nov 2008 23:37:56 -0500

Dear all, this is Hui Zhang from NEC Labs at Princeton. Say hello to
everyone!

Yunfei, the new version is much better than the first one. Following are
several comments/questions on the problem statement:

1. The motivation/selling point for PPSP is not very strong/clear. If
PPSP is to offer a full stack (signaling+transport) of specification,
will service providers like PPLive be willing to rewrite their code from
scratch? 
Should we more consider PPSP as an incremental part to the existing many
P2P multimedia applications?

2. Should we consider VoD application in PPSP? Given the nature of VoD
requests is one-to-one (video server to a requestor), we might want to
focus PPSP on broadcast-based video streaming applications. Do current
service providers like PPlive really use P2P tech for VoD delivery?

3. The idea of bringing CDN into PPSP design is interesting. This CDN
issue can be thought of being a part of the ALTO solution in PPSP, and
the question for discussion is where in the PPSP protocol stack an
interface to the ALTO solution should be explicitly designed and
provided? 

4. The discussion on PPSP transmission protocol (Step 5) got me
confused. Do we really want to enumerate all possible parameters the
current P2P streaming protocols implemented in their chunk
transmissions? Or should the chunk transmission process be mainly left
as a black box to hide individual implementations, which could be deemed
as the core tech by P2P streaming provider, and PPSP will focus on the
interfaces between transmission protocol and signal protocols, and the
transmission protocol and the common new service part such as CDN or
other ALTO parts?

4. We need a good survey on current P2P streaming technologies. I know
there are  some surveys on internet video streaming technologies, but
they typically cover multimedia techniques in traditional centralized
architectures; as for the detailed technologies used by popular P2P
video providers such as PPlive, does anyone known good related articles?

Thanks,

Hui

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
[email-masked]
Sent: Tuesday, November 04, 2008 4:53 AM
To: [email-masked]
Subject: [ppsp] problem statement of ppsp(new version)

Dear all,
   Attached is the updated problem statement of ppsp.Comments and
suggestions are highly welcome.
_______________________________________________
ppsp mailing list
[email-masked]
https://www.ietf.org/mailman/listinfo/ppsp

---

From: "Xiao, Lin (NSN - CN/Beijing)" <[email-masked]>
Date: Wed, 5 Nov 2008 17:33:16 +0800

Hi Yunfei,

I have to say that you did a very good job. : ) 

This is a much clear version with process figures. However, I still have
some questions and comments on it. 
1.	You have two chapter 3 ("3. Peer to Peer Streaming Protocol and
Scope" and "3.Comparison with related protocols") in your draft.
2.	You mentioned "for operators, it's difficult to identify these
different applications". But, why the operators need do it? Is it the
main motivation for operators to use PPSP?
3.	In the scope description, you described 3 kinds of interactions
in PPSP. But, should it also include the interaction between trackers?
Because you also mentioned in the draft that we could use DHT to
organize file trackers.
4.	You wrote "the PPSP includes streaming control and transmission
protocol". I suggest using the term "signaling protocol" to take the
place of "streaming control protocol". Actually, you had refered the
term "signaling protocol" several times in the followed process
description. 
5.	The process in Fig3 is not so clear to understand. Could you
please explain it a little bit in you draft?

Thanks,

Xiao Lin 

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
ext [email-masked]
Sent: Tuesday, November 04, 2008 5:53 PM
To: [email-masked]
Subject: [ppsp] problem statement of ppsp(new version)

Dear all,

---

From: Song Haibin <[email-masked]>
Date: Thu, 06 Nov 2008 11:05:54 +0800

Hi Xiao,

>main motivation for operators to use PPSP?

Good question! My 2 cents, operators may not need to identify these
different p2p applications. But, with PPSP, operators perhaps have the
ability to provide better services such as enhanced ALTO service to the
application, which is beneficial to both p2p application and operators,
although I have not a clear solution in mind.

BR
Song Haibin

---

From: "Hui Zhang" <[email-masked]>
Date: Wed, 5 Nov 2008 22:50:29 -0500

Yes, I agree on Haibin's answer. ISP operators will have the motivation
to use PPSP if it could help them solve the ALTO issue for the
dominating traffic from p2p streaming. 

Hui

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Song Haibin
Sent: Wednesday, November 05, 2008 10:06 PM
To: 'Xiao, Lin (NSN - CN/Beijing)'
Cc: [email-masked]
Subject: Re: [ppsp] problem statement of ppsp(new version)

Hi Xiao,

BR
Song Haibin

---

From: Jun Lei <[email-masked]>
Date: Sun, 09 Nov 2008 16:59:51 +0100

Hallo! This is Jun from Goettingen, Germany.

> dominating traffic from p2p streaming.   
I thought ISP could provide useful information (e.g., ALTO related 
issues) to support PPSP  services, not the other way around. PP2P could 
either rely on the information from ISP or other means (e.g., 
measurement-based metrics) to facilitate applications.

Cheers

Jun

-- 

===========================
Dr. Jun Lei
Research Associate

Computer Networks Group
University of Goettingen
Goldschmidtstr. 7
37077, Goettingen
Germany

-- 

===========================
Dr. Jun Lei
Research Associate

Computer Networks Group
University of Goettingen
Goldschmidtstr. 7
37077, Goettingen
Germany

---

From: Jun Lei <[email-masked]>
Date: Sun, 09 Nov 2008 17:18:41 +0100

Hi, everyone,

Jun Lei (Julie) again.
> P2P multimedia applications?
I agree that the motivations of PPSP is not very clear yet. Hopefully, 
after this BOF meeting it would be much clearer and specific.
> service providers like PPlive really use P2P tech for VoD delivery?
As the PPSP refers to "P2P streaming protocol", I am quite confused 
about considering VoD services in PPSP.  P2P streaming applications 
might have different requirements from that of P2P VoD systems. 
Moreover, it is more complicated to support VoD in a P2P environment as 
the availability of certain video chunks may vary quickly. If you have 
further interests, please refer to our report about VoD services ( 
http://www.net.informatik.uni-goettingen.de/publications/1484/Joost_experiment.pdf). 

To my knowledge, it is nowadays possible to rely on P2P tech to support 
VoD (e.g., fast forward) services. For example, Joost is one of the P2P 
VoD systems and PPLive has provided VoD functions since last year.
> interface to the ALTO solution should be explicitly designed and
I would say that including CDN can be one of the promising solutions for 
PPSP services. However, I am still not quite sure about how to find the 
tradeoff between using CDN and P2P networks for transmitting video 
services.
> video providers such as PPlive, does anyone known good related articles?
My two cents. I would really like to see a good survey on current P2P 
streaming technologies, including both architectural/system design and 
protocol design.

[Hui:] If you specifically refer to PPlive technologies, I would 
recommend the following two papers:

1. Challenges, Design and Analysis of a Large-scale P2P VoD System 
(sigcomm 2008)

2. Insights into PPLive: A Measurement Study of a Large-Scale P2P IPTV 
System (2006)

Cheers

Jun

-- 

Computer Networks Group
University of Goettingen
Goldschmidtstr. 7
37077, Goettingen
Germany

---

From: Jun Lei <[email-masked]>
Date: Sun, 09 Nov 2008 18:11:35 +0100

Hi,Yunfei,

First of all, I think it is a quite interesting and right-timing to
consider PPSP.

Towards your problem statement, I have a couple of questions except for
the ones that I already mentioned in the previous emails.

1. We really need to consider carefully whether we should concentrate on
P2P real-time streaming or inclusive with VoD support. However, just to
my opinion, in the future VoD services might be more promising if we
imagine that IPTV can be really competitive to the current DTV system.

2. You mentioned that "it is the time to draw up an open P2P streaming
protocol". I suppose that you suggest to have a general P2P streaming
protocol for supporting different services, right?

As far as I know, there is some paper about an open P2P streaming
protocol, such as "Substream Trading: Towards an
Open P2P Live Streaming System". Therefore, I would suggest that we
should rather be careful and more specific about the aim of the BOF.

3. For "Problem Statement of PPSP app."

a. startup delay and switching delay are usually long. I totally agree
to get a further investigations on how to reduce the delay, especially
in a P2P circumstance

b. "it is still question if current P2P streaming mechanism work to
support high quality streaming because of different wireless network
environment". I am afraid that I have a different opinion here. Firstly,
wireless network does not necessarily equal to "bad bandwidth support"
but "instable environment". Therefore, instead of providing high quality
streaming I would prefer looking into "stability" and "resiliency".
Secondly, for some wireless users who can only have low bandwidth
support, even we can provide high-quality video transmission it will not
help the service but harm it. Because in that case, the network will be
more congested.

c. with the help of CDN for support VoD could be interesting. I would
suggest to consider caching techniques in parallel. What about the
others' opinions?

4. For "P2P Streaming Protocol Definition and Scope"

a. "the key of PPSP is to find the concrete data (which are piece by
piece) and reassemble them". I suddenly think of "layered video" coding
techniques. It would be helpful in this scenario.

b. for the process of PPSP applications, I have more questions: 1)
sending metrics to the tracker; => how?which kind of?where? 2) tracker
answers with peer list; => if we consider above metrics, how to select
peers? according to its QoS requirements or location-based distribution?
Actually, timing condition is more important here!!!!

.......c. 6) to reassemble chunks in cache for playback; => it is more
complicated for just reassembiling. Besides, it is also relevant to the
underlying transport protocol, whether it is TCP or UDP.

So far, I would keep on tracking the other sections and let you know if
there are any further interesting issues.

Best Regards from Goettingen

Jun

> ------------------------------------------------------------------------
>

-- 

Computer Networks Group
University of Goettingen
Goldschmidtstr. 7
37077, Goettingen
Germany

---

From: Jun Lei <[email-masked]>
Date: Sun, 09 Nov 2008 16:57:03 +0100

Cheers

Jun

-- 

Computer Networks Group
University of Goettingen
Goldschmidtstr. 7
37077, Goettingen
Germany

---

From: "Hui Zhang" <[email-masked]>
Date: Thu, 13 Nov 2008 19:05:53 -0500

[Hui Zhang] this is an interesting point to think more. Actually, it
implies in what mode are we designing/defining PPSP protocol, video
service provider's mode, ISP's mode, or an independent third party
(network protocol developer)'s mode? This will affect the bias/focus of
this work and therefore the adoption of the PPSP protocol in practice.

BTW, thank you for the reference. And please forward my best regards to
Xiaoming.

Thanks,

Hui