Thanks Sherry for the examples, especially for mentioning the distinction 
between P2P and CS.
Here is a use case: There is a nationwide/international event broadcast from a 
web site, such as a presidential election debate or an Olympic competition. The 
web site is voice enabled for friends to chat while watching the event. This 
generates a huge spike in voice traffic, roughly for the duration of the event. 
It would be impossible the design CS SIP  networks to cope with such traffic 
spiking apps IMO. Only a P2P SIP network would make sense in such a scenario to 
cope with fast scalability.

Maybe using cloud computing for large scale CS SIP traffic events may also 
work, but we would need a new WG for SIP-RTP Cloud Computing...  :-)

Henry


On 2/10/09 10:00 AM, "Wang, Sherry" <[email protected]> wrote:

Henry,

Agree: the type of mixed can be a candidate to study mobile P2PSIP. There would 
be cases where capacity and resources may not be limited while keeping a RF 
connection is a challenge by using the model of client/server of existing SIP, 
especially in terms of performance. For example, high-speed flying devices or 
moderate-speed ground vehicles for military use, etc. Your emergency rescue is 
another good example of the mixed type.

Thanks,
Sherry
________________________________
From: [email protected] [mailto:[email protected]] On Behalf Of 
Henry Sinnreich
Sent: Tuesday, February 10, 2009 10:00 AM
To: [email protected]
Subject: Re: [P2PSIP] mobile p2p in p2psip

>there could be three kinds of node in the overlay:  fixed (e.g. desktop), 
>mobile (e.g. >handset) and mixed (e.g. laptop). Fixed  nodes are obviously 
>good candidates for peers of >overlay, while mobile  handsets should be 
>limited in client status considering not only their  >limited capability and 
>resources but also the highly mobile  characteristic. Some devices >like 
>laptop could perform either as peers or  as clients depending on requirement.

I believe this is a key new  insight brought to the WG and should be reflected 
in the WG documents. The  laptop example is quite convincing in such scenarios 
as opening the netbook  for a quick call at the airport and closing it it 
immediately  afterwards.

Henry

-----Original Message-----
From: [email protected] [mailto:[email protected]] On  Behalf Of 
Xiao, Lin (NSN - CN/Beijing)
Sent: Monday, February 09, 2009 9:41  PM
To: ext Song Haibin; Henry Sinnreich; David Artu?edo Guillén; Victor  Pascual 
ávila
Cc: longbwe longbwe; Wang, Sherry; [email protected]
Subject: Re: [P2PSIP] mobile p2p  in p2psip


Hi Bruce and Haibin:

I totally agree with you to  further consider the mobility behavior together 
with the status of the node  (peer or client) in the overlay.

Mobility could bring disconnection and  reconnection which changes the topology 
structure of a P2P overlay. Different  influences are given to peers and 
clients. Clients only need to reconnect with  overlay simply, while peers need 
do data migration and even more before  changing connection. There is no point 
to ask client to install a same complex  protocol with peer, especially in 
mobility scenario. Moreover, the frequent  moving of peers could be a disaster 
for structured overlay. Therefore, it is  necessary to tell which kind of 
devices could perform as peer and which should  work as clients.

Besides the peer/client definition mentioned in Reload  base, the mobility 
character should also be considered to separate them. In my  opinion, there 
could be three kinds of node in the overlay: fixed (e.g.  desktop), mobile 
(e.g. handset) and mixed (e.g. laptop). Fixed nodes are  obviously good 
candidates for peers of overlay, while mobile handsets should  be limited in 
client status considering not only their limited capability and  resources but 
also the highly mobile characteristic. Some devices like laptop  could perform 
either as peers or as clients depending on requirement. The peer  mobility 
issues are mainly brought by this kind of nodes.

So, the  overlay could be constructed by some relative static nodes as peers 
for data  storage and message routing. The highly mobility nodes, which work 
only as  clients, can not cause churn of the overlay topology structure. It 
seems that  we'd better consider the client mobility and peer mobility 
separately to  describe their behavior and to develop their protocols more  
clearly.


Xiao Lin



-----Original  Message-----
From: [email protected] [mailto:[email protected]] On  Behalf Of 
ext Song Haibin
Sent: Tuesday, February 10, 2009 9:54 AM
To:  'Henry Sinnreich'; 'David Artu?edo Guillén'; 'Victor Pascual ávila'
Cc:  'longbwe longbwe'; 'Wang,Sherry'; [email protected]
Subject: Re: [P2PSIP] mobile p2p  in p2psip

Hi Henry and Bin,
>>Frequent changes has to be  managed in order to route messages efficiently.

>>It is not the  same as churn, but it introduces similar challenges, IMHO.

>>This  makes sense and is the reason the present work in the P2P SIP WG
>>we  have peer nodes and client nodes.

>There was an I-D (now expired) on  this:
>Pascual, V., Matuszewski, M., Shim, E., Zhang, H., and S.  Yongchao,
>"P2PSIP Clients",  <draft-pascual-p2psip-clients>

>It was preceded and followed  by many discussions on this topic, such as
>that frequent p2p protocol  messages for peer nodes will quickly exhaust
>the battery.

As the  co-author of this I-D (use my previous name Song Yongchao), I support 
that the  mobile devices should be better to act as clients rather than peers 
whenever  possible. But I guess there are scenarios where only mobile devices 
are  available. In this case, more considerations need to be given to the 
mobility  of a "peer".

Bin, I don't know if this is what you concern  about.

BR
Song Haibin


Just to be clear, clients are a  fully integrated component of the base reload 
protocol.  Motivation for  them and some discussion of related issues is in the 
p2psip-base appendix (and  a much more extensive discussion in pascual-clients 
and others), but the  actual mechanisms to support them should already be in 
the base  draft.

Discussion of further work identifying when a node should be a  peer and when 
it should be a client, or overlay algorithms optimized for  specific types of 
deployments, including "mobile", might be good topics for  further work in new 
drafts, of  course.

Bruce



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