Subject: WAN multicast status

From: Tony Ballardie <[email-masked]>
Date: Thu, 28 Sep 2000 10:08:04 +0100

I'd like to try and generate a discussion on why the idmr and mboned
lists have been so quiet for so long. Why is this?

Is it symptomatic of a trend away from WAN multicast (intra-ISP and
inter-ISP)
in favour of other solutions, or is deployment progress still being made?
If not, what are the reasons? There may be many, but which are uppermost?
No charging model? No application drivers? Lack of control? Lack of
management?

Content distribution networks (CDNs) and companies are emerging, together
with content providers (the 1-many application driver has arrived). The CDN
companies are building virtual topologies, but they seem to be bypassing IP
multicast in their designs in favour of application level mcast and other
solutions. Again, there may be valid reasons (e.g. explicit mgmt, and
control)
but what about the longer term, and scalability?

So, what's the consensus of IP multicast's predicted role in the WAN?

There seems to be very different views in the community on the
WAN multicast issue, which ultimately only serves to generate even
more inertia on the subject. These groups should be providing a
clear message and direction.

Tony

---

From: "John M. Zwiebel" <[email-masked]>
Date: Thu, 28 Sep 2000 12:41:12 -0700

^ 
 ^ I'd like to try and generate a discussion on why the idmr and mboned
 ^ lists have been so quiet for so long. Why is this?

Mostly I believe that now is a time for deployment.  All the talking
is done and folks are actually doing it.

The "major" problem though is still the lack of compelling content
which can reach a very large audience.  Some of the road-blocks
are: 
 --DSL -- last hop can't do multicast (ie DSLAM can't replicate
   a Single packet over different links); 
 --DOCSIS model for cable -- they want access control at layer-2 and
   there isn't a clear winner at layer-3 or above; 
 --ISP provider topologies -- for example AOL has tunnels across
   other ISPs and so (like the DSLAM) multicast replication doesn't happen
   at the last hop; 
 --alternate technologies that don't have anything to do with multicast 
   but which may preclude deployment of multicast in the near term because
   they are incompatable; 
 --failure of Real and Microsoft to provide an open internet broadcast 
   standard, combined with their need to maintain control over the content
   to the last hop to be able to realize a profit from sales of 
   their technology.
 --the knowledge that MSDP can only be a stop-gap protocol for interdomain
   multicast combined with the lack of progress on BGMP which is viewed
   as being too complicated.
 --No way of determining the BW of the link requesting a multicast 
   stream and therefore no way of insuring the link doesn't get overwhelmed.
 --The perception that video over the internet is never going to be any
   better than the 2" window you see over Real

The "good news" is that there is progress being made in each of these
areas, the bad news is that its still going to take too long to get it
done, since (for me at least) it should have happened years ago.

 ^ 
 ^ Content distribution networks (CDNs) and companies are emerging, together
 ^ with content providers (the 1-many application driver has arrived). The CDN
 ^ companies are building virtual topologies, but they seem to be bypassing IP
 ^ multicast in their designs in favour of application level mcast and other
 ^ solutions. 

IMHO, these networks provide the layer-4 and above control over the 
content that a "Republicrat" would require to maintain control over the
content distribution.  The model of "free TV" doesn't translate that well
to an internet that can't put content in every home so advertisers don't
know the size of the potential market.  The CDN network provides better
feedback.

However even CDN can and will recognize benefits from multicast and so
will deploy it and use it.  It would appear to me that they are using
what they know now to gain market position.  They know about multicast
but they don't know that it really works because of all the roadblocks
listed above.

I like to think of this as a free-speech issue though.  :-)  layer-3
multicast is for the "masses" where everyone can be their own TV station
(50,000 channels and nothing on).  Republicrat multicast for the elite
who want to control what the masses see. (1984) :^)

FWIW, enterprise multicast is doing great.

Where do we have to go from here?

Well, SSM, being made possible via IGMPv3 is going to be a
huge driver for interdomain multicast.  It "would be nice" if the web
page that advertises the SSM session could be enhanced to record the 
participants in the group so that it could act as an RP rather than 
having to depend on the RP to be located in the network.

Once that is accomplished, then it "would be nice" if that same RP
process could be used to set up an interdomain bi-dir group.  Since in
bidir PIM the RP can be anywhere, it just becomes a vector end-point.
If you could have a "ip pim  rp-address 0.0.0.0 bidir" (a very gross
generalization of what would be needed) any one sending to a multicast
group served by the default RP would send out a "vector" that receivers
would join to.  All vectors must eventually merge at infinity.

Both of these solutions remove the need for MSDP and BGMP, they do 
present other challenges though that may be more difficult to solve,
but they wouldn't have to be solved in the network.

Finally, I'd like to see the model change for sending to a multicast
group.  Allowing a source to dump traffic on to a network and expecting
the network to just deal with it does not work in large scale and
especially interdomain multicast.  For years at every IETF, the beer
sessions have always devolved to requiring an RTS/CTS multicast sender
capability.  No one wants to do it because it doesn't fit the model
proposed by Deering.  Well, ethernet connectors don't have slide-locks
any longer (at least no one buys ones that do) so its time to change
the sender model or at least have some kind of an alternative to the
current model where anything can get dumped out and it has to
be "taken care of".

2 cents.  Not reflecting anyone's reality but my own.  I'm lost in
a lost world of hopes and dreams of interdomain multicast becoming a 
reality so I can go to the beach.  :-)

------------------------------------------------------------------------------
	John Zwiebel                       Phone: 408-526-5303
	Cisco Systems Inc.                 
	IP Multicast Group

---

From: Henry Sinnreich <[email-masked]>
Date: Fri, 29 Sep 2000 15:56:20 +0100

^ I'd like to try and generate a discussion on why the idmr and
mboned
 ^ lists have been so quiet for so long. Why is this?
A personal opinion in hindsight: The multicast community did not
develop and standardize the AAA and payments issues related to
multicast. ISPs had no business model to justify the investment
in multicast...
Don't blame Real and Microsoft.

Having this explanation, right or wrong, am now trying to get
SIP folks to worry about AAA and payments for SIP services. If
we don't learn from history, we will have to repeat it...

Forgive my comments.

Henry

Henry Sinnreich
MCI WorldCom
400 International Parkway
Richardson, Texas 75081
USA

>-----Original Message-----
>From: [email-masked]
>[mailto:[email-masked]]On
>Behalf Of John M.
>Zwiebel
>Sent: Thursday, September 28, 2000 8:41 PM
>To: Tony Ballardie
>Cc: idmr; mboned; maddogs; [email-masked]
>Subject: Re: WAN multicast status
>
>
>
>
> ^