Subject: Re: Use of SAP in a PIM SSM Network

From: zaid <[email-masked]>
Date: Wed, 15 Nov 2000 01:01:01 -0500

How does this help the end user ? It seems that having a mechanism
similar
in functionality to SAP would be preferred by users. Using the direct
TV model,
a user may not want to access the provider's channel to view the list
of streams
available from that provider. By having a directory service, users
will have one
place to access to choose any content from any provider. Scalability
will be one
of the issues to resolve, ultimately the flexibility of this model
will likely make
it more desirable and usable.

Thanks,
Zaid

-----Original Message-----
From: Mike Luby <[email-masked]>
To: [email-masked] <[email-masked]>; Toerless Eckert
<[email-masked]>; Ross Finlayson <[email-masked]>; Al Adler
<[email-masked]>
Cc: HANSEN CHAN <[email-masked]>;
[email-masked] <[email-masked]>
Date: Tuesday, November 14, 2000 11:36 PM
Subject: RE: Use of SAP in a PIM SSM Network

I think there are different kinds of services that can be offered, and
that
is the difference in the discussion below.  I happen to agree with
Toerless
that webpage access is the more natural way that SSM groups will be
accessed.  Today, there are many many more than 50,000 pieces of
content and
streams available on the web from different content providers, and
there is
absolutely no attempt to make available a centralized listing of all
those
piece of content in one place on one webpage: each content provider
makes
their content available on their webpages through hyperlinks, and the
organization and presentation of that content is designed by them
according
to their needs.  For example, Yahoo has many many pieces of content
and
streams available on its extensive website, and each one is accessed
by the
click of a hyperlink on a given webpage.  There is absolutely no
attempt to
have a global organization of all the content and streams available on
the
Internet.  Thus, I'm wondering what is so special about SSM, and why
it
won't roll into the same access model as all other content and streams
out
there?  I suspect that if something different is attempted to organize
SSM
content and streams that was different than the rest of the Internet,
then
it will have a very limited use on the general Internet.  This is the
beauty
of SSM: it really fits into current practices for making content and
streams
available on the Internet.  Each content provider can independently
source
their own SSM streams just like they put content up on their webpages
today
available through http servers, and they don't have to worry about the
old
style of having a global listing service of all multicast groups in
the
world (which I suspect was there more because of the problems with
having
multicast group address clashes, which is not a problem for SSM), they
just
list their SSM content and streams as they are today on their
webpages.  The
advantage of course is the massive scalability that SSM offers (of
course,
this is assuming it is deployed across the Internet as we all hope).
The
advantage of listing SSM content and streams on webpages is that it is
what
is done today for other content and this way nobody has to change
their
current practices.  Of course, this is not to say that a global
listing
service would not be useful, but I'm not sure I see why this is
anymore
useful than a service that is a global listing service for all content
and
streams on the Internet, i.e., what is special about SSM streams
versus
other streams other than the massive scalability of SSM?

My two cents,
Mike

-----Original Message-----
From: Marshall Eubanks [mailto:[email-masked]]
Sent: Tuesday, November 14, 2000 6:43 PM
To: Toerless Eckert; Ross Finlayson; Al Adler
Cc: HANSEN CHAN; [email-masked]
Subject: Re: Use of SAP in a PIM SSM Network

Toerless Eckert wrote:
>
> > I am trying to understand in a pure SSM network without any shared
tree,
> > how would SAP operate? My understanding is that SAP is
transmitting on a
> > shared tree. Does it mean that we always stuck with a PIM-SM
shared
> > tree, even in a pure SSM network?
>
> I think you have a network without a shared tree and without SAP.
You can
> of course use SSM to get SAP information, but the receivers need to
know
> the address of the sources in the first place, which is a bit beyond
the
> point of what SAP was meant for in the first place. SAP is nice to
have
> in limited environments, but simply trying to broadcast directory
information
> on a world-wide scale is not a scaling solution. Already today lots
of
> SDP sessions are just made available via the web instead of SAP.
>
> -- Toerless

I am not sure that I agree with this. We would certainly be interested
in hosting a directory service using SSM, and I suspect others would
as
well. I would, in fact, claim that in some ways a multicast directory
service scales better than web pages FOR AGGREGATED INFORMATION.

Suppose that one fine day there are 50,000 SSM groups in permanent
operation
.
Clearly, a web page covering ALL of these groups would basically be a
search
engine - just a list would not be useful. If each group was announced
by a sap type packet with a size (say) of 200 bytes, to go through the
entire
list would require 10 megabytes. Even if 8 kilobits/sec were allocated
to
a multicast directory service, it would still take > 3 hours to go
through
all of these announcements. If, however, the groups were divided into
100
classes, each with ~500 members, and each class getting its own SSM
group
for directory announcements, all the sessions in a class could be
discovered in
only 100 seconds, about the time it takes the program announcements on
Channel
1 of my cable TV service to cycle through. I think that such a service
would be
useful; therefore I think that, while SAP may die, multicast session
announcements
will live on.

                                   Regards
                                   Marshall Eubanks

   Multicast Technologies, Inc.
   10301 Democracy Lane, Suite 201
   Fairfax, Virginia 22030
   Phone : 703-293-9624          Fax     : 703-293-9609
   e-mail : [email-masked]     http://www.on-the-i.com

---

From: "Seok Joo Koh" <[email-masked]>
Date: Wed, 15 Nov 2000 15:50:22 +0900

IMHO, the use of SAP may diminish the merit of SSM anyway.
As an alternative for the directory service that users will access to choose
any content from any provider,
we may think of a common web page service, supported by many content
providers.

Anyway, SAP has concerns that its traffic has to be generated and delivered
to all the users including a large number of uninterest users, and this may
give the non-trivial traffic burden to ISPs.

Seok J. Koh

ETRI/PEC
[email-masked]
----- Original Message -----
From: zaid <[email-masked]>
To: Mike Luby <[email-masked]>; <[email-masked]>; Toerless
Eckert <[email-masked]>; Ross Finlayson <[email-masked]>; Al Adler
<[email-masked]>
Cc: HANSEN CHAN <[email-masked]>; <[email-masked]>
Sent: Wednesday, November 15, 2000 3:01 PM
Subject: Re: Use of SAP in a PIM SSM Network

---

From: "Michael Luby" <[email-masked]>
Date: Wed, 15 Nov 2000 01:17:23 -0800

How does what help the end user?  Having web pages?  It is clear that this
is the way everybody uses web pages today, so are you asking how does the
Internet help end users?  I really don't understand this question...

I'm wondering about the preferences of end users.  What makes anyone believe
that they will want yet another service?  What rationale is there that end
user will want anything else other than what they have today on the
Internet, i.e., to to a web page, see a list of content and streams offered
by that provider, and click on the link that corresponds to the service that
they want.  Is anyone seriously suggesting that we need yet another form of
a browser (that would be fine, but it will take a long time for any
substantial set of users to accept it, and in the meantime it behooves the
deployment of SSM to use standard web pages for quick deployment).  What is
the rationale and business decision behind offering SSM through a different
interface other than a standard browser?  What is wrong with the way users
select different services from any provider from a webpage?  As I said
before, it may make perfect sense for someone to put up a webpage that
offers content for a variety of types of content and streams from a variety
of content providers, and this may be even targeted to just SSM streaming
content.  But, what is special about SSM from the user perspective that
makes it compelling enough to offer yet another way to access this content
(which will take a long time to accept)?.  If you really want SSM to catch
on as an Internet (with a capital I) service, it seems the best way to do
this is to change as little as possible from the end use experience when
this is rolled out, which means you provide access to such content using the
standard approach, through web pages.

One of the problems with the standard model of multicast is that it was too
complex to deploy and operate by most ISPs, and too fragile.  Each extra
component on top of what is already offered in the Internet makes it more
fragile and less acceptable.  Whatever can be done to minimize the changes
that need to be made to roll out SSM, either in the underlying
infrastructure or in the end user experience, will greatly increase the
chances that it becomes widely used.

Again, my two cents ... flame out ... and let others put there two cents in.

Mike Luby

-----Original Message-----
From: zaid [mailto:[email-masked]]
Sent: Tuesday, November 14, 2000 10:01 PM
To: Mike Luby; [email-masked]; Toerless Eckert; Ross Finlayson;
Al Adler

Thanks,
Zaid

-----Original Message-----
From: Mike Luby <[email-masked]>
To: [email-masked] <[email-masked]>; Toerless Eckert

My two cents,
Mike

-----Original Message-----
From: Marshall Eubanks [mailto:[email-masked]]
Sent: Tuesday, November 14, 2000 6:43 PM
To: Toerless Eckert; Ross Finlayson; Al Adler
Cc: HANSEN CHAN; [email-masked]
Subject: Re: Use of SAP in a PIM SSM Network

tree,
transmitting on a
shared
You can
know
the
have
information
of

                                   Regards
                                   Marshall Eubanks

---

From: Marshall Eubanks <[email-masked]>
Date: Wed, 15 Nov 2000 10:09:22 -0500

Dear Mike;

   Toerless presented an argument that session announcements wouldn't
scale. I presented a counter argument, a scheme which does scale, which no-one has
refuted.

Michael Luby wrote:

> interface other than a standard browser?

I think what you are forgetting is that in the near future people will not necessarily
access the internet (and particularly internet broadcasts) through a box with a web server. I doubt that
people with a handheld 3G wireless IP "SSM-Man" audio player on the beach are going to want to
to look at web sites to select content. A scrollable list of content by genre (such as what the
Kerbango box has, but via multicast) would make more sense.

   As for Internet TV : I have cable television at home. It broadcasts a rotating schedule of
what's on the air on channels 1 and 2 - a session announcement, of a sort. I use it all the time.
So do lots of other people, including many who have never used any sort of browser.
SSM session announcements will have similar utility, and I have no doubt that they will be used.

                                                            Marshall

> What is wrong with the way users

T.M. Eubanks
Multicast Technologies, Inc
10301 Democracy Lane, Suite 410
Fairfax, Virginia 22030
Phone : 703-293-9624
Fax     : 703-293-9609
e-mail : [email-masked]     [email-masked]

http://www.on-the-i.com http://www.buzzwaves.com

---

From: Toerless Eckert <[email-masked]>
Date: Wed, 15 Nov 2000 12:23:55 -0800 (PST)

> scale. I presented a counter argument, a scheme which does scale, which
> no-one has  refuted.

Just because my email server was upgraded ;-)

I hope that i just said that session announcements in the way it is currently
handled in the Internet does not scale. Session announcements by themselves
will scale, but by doing so, we implicitly need to introduce directory like
selection mechanism that simultaneously can give us all the information
to use SSM too.

All the examples cited (cable-tv, wireless devices) show that the session
information you may want to receive in a broadcast style are limited
in quantity (certainly not "everything from the internet"). Also they
typically will be managed by someone providing the access, like AT&T for
the cable-tv or whoever gives you the wireless connectivity. You may not
call it web anymore, but the more you get into ubiquitous devices, the more
will you see that they all have some initial portal to services.

In this space, yes, you may want to "broadcast" session information, and 
yes, you can easily use SSM, because you can source that broadcast from
a well-known source address. Heck, why not use our beloved anycast mechanism ?

The problem with broadcasting session information is that nobody in his sane
mind (hopefully) should think that you would want to get a flat, 
undifferentiated broadcast of all the sessions in all the world, which is
what you would get today with SAP. And once you are putting structure into
this, then you say that you want to select which part you want to receive,
and that already means that you have keys for selection, and those keys
just need to map to the source addresses originating the broadcast selection,
so that SSM can be used.

Cheers
	Toerless

---

From: "Michael Luby" <[email-masked]>
Date: Wed, 15 Nov 2000 23:17:02 -0800

Marshall,

You make some good points about future devices coming into the picture that
will not necessarily access the current webpages on the Internet, most
likely because they are too rich to be displayed on initial versions of
wireless devices.  However, for the Internet, where I believe SSM has a
future, I still believe that it makes most sense to access SSM content the
same as any other content, via clicking on a link on a web page.  This
requires no changes to current practices of content providers, other than
deploying SSM (which is a large hurdle, and that is the point, this is large
enough of a hurdle that changing anything else and putting even more hurdles
in  the way of acceptance will make deployment of SSM all that much slower
than it already is likely to be.)

I do think that there will be as you say a whole new generation of devices
as you point out that will need another way to access content other than
going to a standard Internet webpage which is too rich, and one possible way
to do this is some kind of push of a session directory to the device and
then the end user clicks on the links that they want to access.   Hmmm, this
is beginning to sound just like the AOL service where all users have a
common AOL homepage to start there searches from, but in this case the
homepage would be specially desgined for display on the devices and would
show what categories of content is available, and then the user clicks on
the link to get to a particular category, and the a scollable list of
available content within the category is shown which can be clicked on.  The
difference is that the webpages may be specially designed to be small so
that it can be viewed reasonable in a wireless device, for example.

I guess I'm not really seeing the difference between a scrollable list of
content by genre (= lists of links on different webpages, one for each
genre), whether it be for cable T.V. or for the 3G wireless device.  Aren't
all of these just different forms of webpages that show what content is
available, and it is just that some are more primitive, more succinct, or
more compact than others?  Isn't the directory service available on cable
T.V. over time slowly evolving into something more like a webpage?  Of
course, it is fine if the webpage itself is sent out over an SSM group,
nothing stops that from happening, just like any other piece of content may
be delivered more efficiently using SSM if there is a lot of concurrent
access to the content, like the homepage for the device and perhaps in your
example all of the webpages for each genre that lists all of the content
available within each genre (which may all be available using SSM).

Mike

-----Original Message-----
From: Marshall Eubanks [mailto:[email-masked]]
Sent: Wednesday, November 15, 2000 7:09 AM
To: [email-masked]
Cc: zaid; Toerless Eckert; Ross Finlayson; Al Adler; HANSEN CHAN;
[email-masked]
Subject: Re: Use of SAP in a PIM SSM Network

Dear Mike;

no-one has
refuted.

> interface other than a standard browser?

I think what you are forgetting is that in the near future people will not
necessarily
access the internet (and particularly internet broadcasts) through a box
with a web server. I doubt that
people with a handheld 3G wireless IP "SSM-Man" audio player on the beach
are going to want to
to look at web sites to select content. A scrollable list of content by
genre (such as what the
Kerbango box has, but via multicast) would make more sense.

   As for Internet TV : I have cable television at home. It broadcasts a
rotating schedule of
what's on the air on channels 1 and 2 - a session announcement, of a sort. I
use it all the time.
So do lots of other people, including many who have never used any sort of
browser.
SSM session announcements will have similar utility, and I have no doubt
that they will be used.

                                                            Marshall

T.M. Eubanks