mulcast assignments

PC paul4004 at
Thu May 3 23:31:42 UTC 2012

And I've seen plenty of gear without SSM support:

Some of the larger offenders:
Juniper Clusters.
Cisco ASA
Some Linksys managed switches (no IGMP snooping support for it).

I really wouldn't think it'd be that hard to implement SSM if the equipment
had functional ASM support, but that's a story for another day I guess.

Most development for mcast largely occurred between  the last 90s and early
2000s it seems.  Since ~2005 once the hopes of inter-domain multicast
fizzled and IPTV failed to launch in any meaningfully way, multicast
development has largely been neglected by the major equipment vendors and
cast away as some funky thing used by certain enterprise and educational
market segments.

At least, IMHO...

On Thu, May 3, 2012 at 6:44 PM, Greg Shepherd <gjshep at> wrote:

> On Thu, May 3, 2012 at 3:32 PM, Nick Hilliard <nick at> wrote:
> > On 03/05/2012 21:00, Greg Shepherd wrote:
> >> Sure, but GLOP predated SSM, and was really only an interim fix for
> >> the presumed need of mcast address assignments. GLOP only gives you a
> >> /24 for each ASN where SSM gives you a /8 for every unique unicast
> >> address you have along with vastly superior security and network
> >> simplicity.
> >
> > SSM is indeed a lot simpler and better than GLOP in every conceivable
> way -
> > except vendor support.  It needs igmpv3 on all intermediate devices and
> > support on the client device.  All major desktop operating systems now
> have
> > SSM support (OS/X since 10.7/Lion), but there is still lots of older
> > hardware which either doesn't support igmpv3 or else only supports it in
> a
> > very primitive fashion.  This can lead to Unexpected Behaviour in naive
> > roll-outs.
> I haven't seen a piece of network gear without SSM support in a very
> long time. The weak link is the applications. It was the OS stacks but
> that's finally caught up - it only took it 10 years...
> The weakest link is simply multicast deployment - if it's not
> everywhere it has little use. That's what AMT is promising to fix. And
> with AMT comes the opportunity to bring SSM to non-SSM-capable apps if
> it is implemented correctly.
> Greg
> > Nick
> >

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