Subject: A better name than ISM

From: Ross Finlayson <[email-masked]>
Date: Fri, 24 Nov 2000 15:14:49 -0800

At 12:32 PM 11/24/00, Hugh Holbrook wrote:
>I agree.  I think we should raise this issue at maddogs.  It feels
>kind of like a nit, but I think naming is really important -- bad
>names can cause SO much confusion...

OK, there seems to be consensus that "Internet Standard Multicast"/ISM is 
not the best name/acronym for the current multicast model.  As for an 
alternative - IMHO, either "Any-Source Multicast"/ASM or 
"Source-Independent Multicast"/SIM would be better.  Personally, I prefer 
"SIM" for (as Mike noted) its symmetry with SSM (given that SSM stands for 
"Source-Specific Multicast", *not* "Single-Source Multicast".)

If this stuff takes off, these acronyms could end up being widely learned 
and used by students, engineers, trade rags, so I agree with Hugh that 
having a clear, non-confusing name/acronym is important.  (For example, 
think about how many people have already confused the acronyms RTCP and RTSP.)

         Ross.

---

From: Mark Handley <[email-masked]>
Date: Fri, 24 Nov 2000 17:13:06 -0800

>"Source-Specific Multicast", *not* "Single-Source Multicast".)

SIM is a rather overloaded abbreviation, and ASM implies the receivers
have no control over which sources they listen to, which is no longer
true with IGMPv3.

The key difference is that in SSM receivers join a source/channel,
whereas in ISM they join a group (or group of sources).  The ideal
name would probably be Group-Specific Multicast, but that acronym is
taken.  Source-Group Multicast would work too, but (informally at
least) that acronym is also taken.  How about Group-Addressed
Multicast (GAM), Internet Group Multicast (IGM) or just Group
Multicast (GM)?

Cheers,
	Mark

---

From: Toerless Eckert <[email-masked]>
Date: Fri, 24 Nov 2000 21:22:24 -0800 (PST)

> Multicast (GAM), Internet Group Multicast (IGM) or just Group

I think the original term used in rfc1112 is "Host Group Multicast",
which would abbrviate to HGM.

Cheers
	Toerless

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From: Marshall Eubanks <[email-masked]>
Date: Sat, 25 Nov 2000 10:19:22 -0500

> which would abbrviate to HGM.

For what it's worth, none of the new choices mentioned on the
list seem significantly better than ISM to me. If there was 
going to be a change (again),
I would suggest GSM (any possible three letter choice is undoubtedly "taken"
by some project somewhere...).

There is something to be said for "net-masking" for humans - having two
related acronyms be similar, but disjoint at the beginning or the end
(SSM vs ISM or SSM vs GSM, say), helps
the reader to remember both better. If, like GSM, the phrases behind the acronyms
are also parallel, so much the better.

                                   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: Jon Crowcroft <[email-masked]>
Date: Sun, 26 Nov 2000 15:21:22 +0000

right - ssm is not multicast. its really a very big departure from
the entire IP world - 

the difference between unicast and deering's multicast at the
fundamental service level was very thin - anyone can send to either,
and anyone can receive what is sent to them,
or choose not -the rest was address allocation and routing

the channel model in SSM explicitly creates an association from
address allocation, source, and receiver set that is much less
flexible (although as everyone keeps saying, appears to cover the
majroity of the _current_ "compelling", or as i prefer, fashionable
applications:-)

i'd prefer we change the name of SSM back to channel

 >>Multicast (GAM), Internet Group Multicast (IGM) or just Group

 cheers

   jon

---

From: "Michael Luby" <[email-masked]>
Date: Sun, 26 Nov 2000 11:30:35 -0800

Well, I view SSM as somewhere in between IP unicast and the original IP
multicast model, and in fact I think of SSM as a natural interpolation
between the two that has a lot of advantages over IP unicast and the
original IP multicast model, as well as some of its own natural limitations.
Thus, I'm not understanding why it is a very big departure from the entire
IP world.

It seems to me that unicast has the most explicit association:
sender is explicitly named and not changable.
receiver is explicitly named and not changable.

SSM is next:
sender is explicitly named and not changable.
receiver set can vary dynamically.

Then, the original multicast model:
sender set can vary dynamically.
receiver set can vary dynamically.

And, yes, it is ok to use the word fashion instead of compelling, if fashion
is defined to mean what people are *currently* putting a concerted effort
into to deploy commercially and create a revenue stream.  And you are right,
it may be fashionable in a couple of years to want to deploy commercially
applications that are more suitable to the original multicast model.  Let's
see.

I'm sure we can continue this conversation at a beer BOF ... (sunday
evening, monday evening?)

Mike

-----Original Message-----
From: Jon Crowcroft [mailto:[email-masked]]
Sent: Sunday, November 26, 2000 7:21 AM
To: Mark Handley
Cc: [email-masked]; [email-masked]
Subject: Re: A better name than ISM

 cheers

   jon

---

From: Toerless Eckert <[email-masked]>
Date: Sun, 26 Nov 2000 14:30:06 -0800 (PST)

Ok, so this is how i perceive the problem:

a) For just the technology, it's completely arbitrarily how we abbreviate
   the "IP Multicast service as defined in RFC1112".

b) From the perspective of being able to completely confuse users, it's
   ideal to change the abbreviation every once so often. I certainly
   would rather like to avoid this for the documentation i have to provide
   to our users.

Is there any way on how we could please converge on some abbreviation for
the "IP Multicast service as defined in RFC1112" - and i mean an abbreviation
that would then be at least highly recommended to be used in all IETF
related papers (rfcs, etc..) ? Od course, everybody is still free to
call it the "IP Multicast service as defined in RCC1112".

Just wondering. Given that it's just a word, it shouldn't be too difficult.
Up to a few weeks ago, i would have thought of simply voting on this to be
an easy solution to the issue, but in the meantime i've learned that there
are certain challenges associated with counting votes here in this country...

Cheers
	Toerless

---

From: Marshall Eubanks <[email-masked]>
Date: Mon, 27 Nov 2000 10:41:28 -0500

> are certain challenges associated with counting votes here in this country...

Dear Toerless;

   Referring to "votes" in an IETF context (or at an IETF meeting) is a good way
to get razzed.

   I would say that rough consensus exists on SSM and ISM. I therefore
would say, don't change it.

   The worst arguments in a group tend to occur about things that do not matter, as
there is no good way to resolve them, except by fiat...

--
                                 Regards
                                 Marshall Eubanks

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