All things related to multicast

[Joel Jaeggli <>]

On Thu, 13 May 2004, John Zwiebel wrote:

> There is also a very old powerpoint that was multiuser capable.  It
> was available as a beta on Macs.  Hmmm... wonder why it died?  :-)
> 
> I agree with Tom that multicast isn't going to take off until
> there are high-BW applications.

There's are plenty of high bandwidth applications out that haven't taken
off because of thin edge network connectivity and lack of multicast. some
of them already support multicast (videolan, quicktime broadcaster, real
broadcaster etc) just fine as well it's just that you can't use it if it
isn't there.
 
> Moving on, those high-BW applications are -NOT- going to use
> ASM.

My sense of ssm penetration is that it's actually on a retrograde path,
because of windows personal firewalls, switch vendors (cisco included) and
so forth there may actually be a lower penetration of ssm capable devices
then there were two years ago.

> So, the barriers to multicast are:
>    -- last-mile
>       Where is AMT or how do we break the monopoly that the
>       home providers have.
>    -- no source discovery protocol that doesn't depend on multicast
>       (ie, sdr doesn't scale to an interdomain environment and
>       continued attempts to make it do so will not work.  Storing
>       this information "in the network" by pushing it out via multicast
>       is OK in a dense environment, but the Internet is not a dense
>       environment.)  This has to be an application level protocol
>       like DNS (ie, putting the SDP file on a web page, although not
>       elegant, does work.  Perhaps a discussion of why this isn't
>       "good enough" is in order?)
>    -- MLDv2 and IGMPv3.  Its in KAME so "soon" will be in FreeBSD and
>       therefore OSX (I hope).  Perhaps a little lobbying of the FreeBSD
>       folks to incorporate the KAME IGMPv3 and MLDv2 would be in order?
>       (I don't know the process)

windows based personal firewalls that don't handle multicast well 
including the microsoft one. are the biggest threat againt your installed 
base of ssm or even asm capable clients.
 
> This forum has been wondering about the sasser attacks on MSDP.  SSM
> would eliminate this kind of an attack.  SSM does open up for a 
> "reverse"
> attack where a "evil-doer" could join every IP address in the world 
> causing
> creation of lots of state.
> 
> I'm often accused of being unrealistic because I keep saying "kill asm" 
> and
> "Kill MSDP".  Perhaps I should change my mantra to "allow it to wither".
> I keep seeing efforts (I think) wasted on making ASM better because we 
> have
> to support all those legacy hosts that don't support IGMPv3 so can't do
> SSM.  Yet, I sure don't see the explosion of multicast that was suppose 
> to
> happen because we maintained that backward capability.
> 

-- 
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Joel Jaeggli           Unix Consulting         

    
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