Subject: [p2p-sip] Use cases attributes

From: spencer at mcsr-labs.org (Spencer Dawkins)
Date: Tue, 3 Oct 2006 15:13:34 -0500

Enrico sent a note to the list about the Use Case matrix at 
http://www.p2psip.org/P2PUseCases.php, pointing out that the matrix had "no" 
for "Interaction with CS-SIP" for the following use cases:

+ Impeded Access
+ Ad-Hoc and Ephemeral Groups
+ Extending the Reach of Mobile Devices

and suggesting that these be listed as "when available".

My thinking (which may be questionable, because it's already been questioned 
:-) was that

+ "Impeded Access" is not likely to have CS-SIP "available", because the 
motivation for the use case, as I understood it, was that the CS-SIP 
infrastructure wasn't available, wasn't usable, or was actively hostile to 
SIP users. In this case, it seemed unlikely that the overlay peers would 
want to use CS-SIP, especially via the overlay itself.

+ "Ad-Hoc and Ephemeral Groups" and "Extending the Reach of Mobile Devices" 
did seem like more likely candidates for "Interaction with CS-SIP", at least 
based on the motivation. My hesitation here is more about identity - if I'm 
the Proxy Peer providing "Interaction with CS-SIP", how much do I know about 
the other peers in these use cases, and am I willing to provide the Peer 
Proxy service, since I certainly wasn't configured to know anything special 
about my peers in the first case, and likely in the second case as well?

So I could go for "when available" in "Ad-Hoc and Ephemeral Groups" and in 
"Extending the Reach of Mobile Devices", if it seems useful to others. Does 
it seem useful to others?

Thanks,

Spencer

----- Original Message ----- 
From: "Enrico Marocco" <enrico.marocco at telecomitalia.it>

Spencer Dawkins wrote:
> I would like to keep this spreadsheet in sync with the drafts, of course, 
> so the contents will change as people discuss use cases.
>
> I should add that this spreadsheet is the product of discussions with a 
> number of people, including Seaward, so please view me as the editor, not 
> as the author.
>
> As always for editors, comments are welcome.

First of all, thank you for the great work!

Then, a couple of comments on the "Interaction with CS-SIP" column,
which is the one I care more about ;-)  I expected to see a "when
available" instead of a cold "no" at least in the following rows:
+ Impeded Access
+ Ad-Hoc and Ephemeral Groups
+ Extending the Reach of Mobile Devices

In such use cases, when some peer in the overlay shares the resources
for relaying SIP and media traffic to and from the Internet, the overlay
itself should act exactly as a conventional SIP network, IMHO.

--
Enrico

---

From: enrico.marocco at telecomitalia.it (Enrico Marocco)
Date: Wed, 04 Oct 2006 09:48:09 +0200

> want to use CS-SIP, especially via the overlay itself.

Generally speaking, a P2PSIP Overlay has CS-SIP "available" when at
least one of the participating peers is able (and willing) to provide
the Proxy and Media Relay services.  This could certainly not happen
when all peers have "impeded access", but if one has additional
resources (e.g. an additional DSL link) the interworking is possible.
Obviously the decision depends on considering the "Impeeded Access" for
some or all peers.

> about my peers in the first case, and likely in the second case as well?

As above, here the availability depends also on the willingness to
provide the needes services.

> it seem useful to others?

My vote doesn't count, does it? ;-)

-- 
Ciao,
Enrico

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From: spencer at mcsr-labs.org (Spencer Dawkins)
Date: Wed, 4 Oct 2006 07:19:58 -0500

Hi, Enrico,

(Well, of COURSE your vote counts!)

My view of "impeded" may be more draconian than most - where the 
infrastructure provider is actively searching for traffic they don't 
like/approve of, and doing what they can to obstruct it. I'm thinking of 
something like the practice (in the United States) of prohibiting server 
operation on residential access networks, and dropping customers who violate 
this contract condition, and I'm pretty sure that enterprises who don't want 
to use SIP internally would not be amused by people who participate in 
P2PSIP overlays that cross its enterprise firewalls.

So I was assuming that no one would want to call attention to themselves by 
sending P2PSIP traffic over network boundaries where we find firewalls, 
policy enforcement points, etc.

In a more benign view of "impeded", the infrastructure provider would love 
to provide SIP but isn't competent to do so, and is willing to watch someone 
else provide SIP connectivity for its customers. In this case, "when 
available" makes much more sense.

So I'm trying to understand how often "impeded" is draconian, and how often 
it's incompetent :-)

Thanks,

Spencer

----- Original Message ----- 
From: "Enrico Marocco" <enrico.marocco at telecomitalia.it>
To: "Spencer Dawkins" <spencer at mcsr-labs.org>
Cc: "P2P-SIP" <p2p-sip at cs.columbia.edu>
Sent: Wednesday, October 04, 2006 2:48 AM
Subject: Re: [p2p-sip] Use cases attributes

-- 
Ciao,
Enrico

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From: enrico.marocco at telecomitalia.it (Enrico Marocco)
Date: Wed, 04 Oct 2006 16:46:36 +0200

> So I'm trying to understand how often "impeded" is draconian, and how often 

My view of "impeded" is actually less draconian than yours.  When I
think about impeded access, I immediately think about guests in my
company's network.  In fact, since I'm a registered user, even behind a
firewall I can use the local SIP service for talking with people on the
Internet, but there is no way for a visitor on the same LAN to access
the same service.  However, I'd be happy to share my permissions with
guests attending a meeting or a conference with me and, hopefully,
P2PSIP will let me do that.

The same result could more easily be achieved using a system for
provisioning temporary accounts on the SIP server, so I have to admit
that this is a clear matter of incompetence, but I'm pretty sure it is
quite a common case.

-- 
Ciao,
Enrico

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