Subject: [p2p-sip] What are we doing, question 2

From: RADHIKA.R.ROY at saic.com (Roy, Radhika R.)
Date: Tue, 6 Jun 2006 10:28:49 -0400

Inline [RRR]

  _____  

From: Brijesh Kumar [mailto:bk9001 at gmail.com] 
Sent: Monday, June 05, 2006 5:51 PM
To: Roy, Radhika R.
Cc: Krishna Sankar (ksankar); p2p-sip at cs.columbia.edu
Subject: Re: [p2p-sip] What are we doing, question 2

On 6/5/06, Roy, Radhika R. <RADHIKA.R.ROY at saic.com
<mailto:RADHIKA.R.ROY at saic.com> > wrote:

KS:

To support p2pSIP for mobile nodes (if not mobile devices per se) should
not be difficult.

I beg to differ with above assessment.

[RRR] The mobile ad hoc network (MANET) WG has solved (or is solving) the
most complex problems that p2pSIP ever can imagine. That is, a MANET network
is mobile and its topology is ad hoc. It is forced to use p2p schemes. So,
they have addressed two serious problems at the same time: 1. Ad hoc mobile
network whose topology changes as each mobile node moves with different
speeds (e.g., vehicles move at the speed of 10 to 100 miles hours, unmanned
airborne vehicles may move at the speed of 200 to 500 miles per hour) in
different directions and 2. MANET is forced to address p2p networking
schemes because all nodes are mobile.

[RRR] P2pSIP is not considering the mobility assuming that the lower network
will be able to take care of the mobility, and the p2pSIP is hoping that,
like normal SIP, it will also be transparent to mobility, and no special
works are needed. For example, normal SIP is being used in 3G cellular
wireless networks. However, MANET is inherently very complexly and is
different from those 3G networks because it, unlike 3G, force to use p2p
schemes.

[RRR] The idea is this: To use normal SIP over MANET is far from ideal as
normal SIP is not suitable for p2p schemes. However, p2pSIP will be ideal
for MANET as both of them are used in p2p environment.

Actually, a change in the IP address would result in the change in a node's
identity. Also, a number of DHT configuraion algorithms (specially
hierarchical organization) try to optimize overlay organization on the basis
of a node's geographical location with respect to certain reference points.
That has major implications on a DHT's operation since it may require DHT
reconfiguration as well as affect where a node will be placed in the
overlay. 

[RRR]  The address changes in p2p environments in the IP network due to
mobility and the complexity of routing where the network topology are being
changed very frequently are being solved successfully in MANET in p2p
environment. As I indicated above, MANET has a wealth knowledge how to
address those, and we, being in the p2pSIP WG, do not need to spend energy
on this.

[RRR] That is why I am extremely hopeful that it will not be difficult to
solve mobility problem for the p2pSIP once we develop the p2pSIP standard at
the application layer.

I haven't seen many papers that have analyzed large scale networks for the
effect of node identity  change due to node mobility in P2P networks so  it
is not clear to me why would you say that it is not "difficult". 

[RRR] See above. The most complex problems of mobility in p2p schemes are in
the lower network layer that MANET is addressing as you have explained above
(e.g., IP network address changes). I also add another one: Topology of the
network itself changes.

[RRR] Once p2pSIP using all its features including DHT is standardized,
there are is not much serious complex problems to solve like what MANET WG
has been doing. I usually call these problems as some minor "patch" works
(sorry for lack of proper words) for standardization.

--bk 

IETF Mobile Ad Hoc Network (MANET) WG has already done 
the most difficult works in this p2p networking environment: Network
Routing and QoS support.

So, it will be rather easy to support the p2pSIP application protocol
that will ride over the network layer MANET protocol. 

In fact, we will be working cooperating with them to complete our work:
p2pSIP Application Layer to the MANET Network Layer.

Best regards,
Radhika R. Roy

-----Original Message-----
From: p2p-sip-bounces at cs.columbia.edu
<mailto:p2p-sip-bounces at cs.columbia.edu> 
[mailto:p2p-sip-bounces at cs.columbia.edu
<mailto:p2p-sip-bounces at cs.columbia.edu> ] On Behalf Of Krishna Sankar
(ksankar)
Sent: Monday, June 05, 2006 11:43 AM
To: David Barrett; p2p-sip at cs.columbia.edu <mailto:p2p-sip at cs.columbia.edu> 
Subject: Re: [p2p-sip] What are we doing, question 2

My view of the P2P-SIP world ...

> 2) Does P2PSIP work on mobile devices assigned dynamic IP addresses? 
<KS>
        Yep, definitely. Might not be that easy
</KS>

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