Subject: Re: [ppsp] [alto] problem statement draft of peer to peerstreaming protocol(PPSP)

From: "zhangyunfei" <[email-masked]>
Date: Mon, 1 Jun 2009 22:46:05 +0800

Hi Gyorgy,
   Thanks so much for your comments.Please see inline about the reply.

                            Yunfei

zhangyunfei
2009-06-01

发件人： Gyorgy Dan
发送时间： 2009-06-01 18:50:56
收件人： zhangyunfei
抄送： 
主题： Re: [alto] problem statement draft of peer to peerstreaming protocol(PPSP)

Hi  Yunfei,

In  general,  I  find  the  effort  very  good,  we  are  ourselves  working  on  
something  similar  at  the  moment.

Some  comments  to  the  draft  you  sent  out  a  few  days  ago.

In  Section  4.1  you  mention  two  problems  of  tree  based  systems:  tree  
depth  and  handling  churn.

I  would  argue  that  tree  depth  is  not  such  a  big  problem  (several  
multi-tree  based  systems  were  shown  to  have  reasonable  tree  depths).  I  
would  say  that  the  biggest  problem  is  the  difficulty  of  detecting  the  
upload  bandwidth  of  the  peers.  Consequently,  it  is  difficult  to  
determine  the  correct  fanout  of  a  peer  in  the  trees,  which  makes  
adaptation  to  changing  bandwidths  very  hard.

Reply: Thanks for the reminding.I will add it to the draft.I guess it could be solved by the peer piggybacking the dynamic bandwidth infomation in the same time(or just after) when the peer sends data stream to other peers.

At  the  same  time  I  would  argue  that  it  is  very  important  to  keep  the  
PPSP  signaling  protocol  as  flexible  as  possible  so  that  different  
algorithms  can  be  implemented  on  top  of  it.  From  the  draft  I  had  the  
impression  (e.g.,  Section  5.1,  5.2)  that  you  would  like  to  create  
standard  buffer  map  representations,  etc.  The  requirements  of  different  
algorithms  might  however  be  distinct,  so  there  might  be  a  need  for  a  
(extendible)  set  of  representations.  The  same  applies  for  peer  
discovery,  peer  information,  etc.
Reply:I agree with your point.This is what we are going to develop.

Regards,
György
-----
http://www.ee.kth.se/~gyuri

zhangyunfei  wrote:
>  Hi,all,
>  I  have  submitted  problem  statement  draft  of  peer  to  peer  streaming  
>  protocol(PPSP)to  IETF  website  in  the  following  
>  link.(http://www.ietf.org/internet-drafts/draft-zhang-ppsp-problem-statement-03.txt)  
>   <http://www.ietf.org/internet-drafts/draft-zhang-ppsp-problem-statement-03.txt >  
>  which  may  related  to  ALTO  WG.Any  comments  and  suggestions  are  highly  
>  welcome.
>  The  abstract  is  as  follows:
>
>  We  propose  to  develop  an  open  peer-to-peer  (P2P)  streaming  protocol  
>  named  PPSP.  This  document  describes  the  problems  related  to  PPSP  and  
>  outlines  considerations  that  have  to  be  taken  in  account  when  arriving  
>  at  equitable  solutions.
>
>  BR
>
>  Yunfei
>
>
>  ------------------------------------------------------------------------
>  zhangyunfei
>  2009-05-27