All things related to multicast

[Leonard Giuliano <>]

It strikes me as odd that lack of snooping could CAUSE mcast to not be 
deployed and used.  Lack of snooping is only a problem when there's too 
much mcast (and one could argue that's a good sign for mcast deployment- 
there's too much mcast!).

It's also been my experience that operators (and humans in general) are 
generally not proactive enough to delay the deployment of a compelling 
service bc of the anticipation of a potential problem down the road.  It's 
usually some other, more pressing reason.

-Lenny

On Sat, 20 May 2006, Richard Mavrogeanes wrote:

-) Joel,
-)  
-) Yes, MLDv2 snooping...but this may be too limiting a statement because 
vendors can/should implement what works for them to enable end-to-end IPV6 
multicast. Some vendors do some proprietary things to enhance multicast 
behavior I seem to recall, but the result is consistant with snooping...that 
is, you can join a group the switch already has without a trip to the router, 
flooding is avoided, and group leaves are pretty quick thus avoiding local 
oversubscription.
-)  
-) We have multicast-enabled hundreds of colleage and K-12 networks in the 
last few years, as well as district-level networks that interconnect many 
schools.  To your point, there remains FUD on the part of the local IT 
manager with regard to multicast rollout...but we've been able to overcome 
these objections and I would say multicast is at last becoming conventional 
wisdom.  I think this is true because it works when properly deployed and 
gives the deploying institution capabilities otherwise virtually impossible.
-)  
-) My concern is that those forward-thinking institutions planning a 
migration to IPV6 will encounter the same trouble the industry as a whole has 
only recently begun to overcome with IGMPv2 and IGMPv3.  I think I'm hearing 
it's not possible to deploy IPV6 multicast in any sort of reasonable 
end-to-end way...yet.  Please keep in mind that my perspective for this 
thread is largely inside the enterprise, not so much the WAN.
-)  
-) /rich
-)  
-)  
-) 
-)      -----Original Message----- 
-)      From: Joel Jaeggli 
[mailto:]
 
-)      Sent: Sat 5/20/2006 3:08 PM 
-)      To: Richard Mavrogeanes 
-)      Cc: Alan Crosswell; 

 
-)      Subject: Re: IPV6 Multicast
-)      
-)      
-) 
-)      Richard Mavrogeanes wrote:
-)      > Alan,
-)      > 
-)      > Well, the next release supports IPV6, and perhaps multicast too.
-)      > 
-)      > The trouble/question is local Ethernet switch support ("snooping" 
behavior), and I'm hoping someone has some war stories to share.  It was bad 
enough getting the switch vendors fully onboard with IGMP, and I wonder where 
they are with IPV6 multicast.  Obviously, IPV6 is not so useful if it can't 
reach the end user (desktop).
-)      
-)      By "snooping behavior" I assume you mean mldv2 snooping?
-)      
-)      It always seems like people are looking for a reason to not deploy 
this
-)      (foo multicast technology).    "If we just had igmpv2/v3/mld/v2 
capable
-)      switches there'd be no impediment to use rolling it out."
-)      
-)      The fact of the matter is l2 switching hardware will almost always
-)      evolve more slowly than host stacks or routers. Looking inside 
ethernet
-)      frames is an expensive exercise for most l2 switches.
-)      
-)      What do you do with an elephant with three balls?
-)      
-)      Walk it, and pitch to the giraffe...
-)      
-)      > /rich
-)      > 
-)      >
-)      >       -----Original Message-----
-)      >       From: Alan Crosswell 
[mailto:]
-)      >       Sent: Sat 5/20/2006 12:54 PM
-)      >       To: Richard Mavrogeanes
-)      >       Cc: 

-)      >       Subject: Re: IPV6 Multicast
-)      >      
-)      >      
-)      >
-)      >       Abiline and most of the gigapops support it.  There are some 
issues with
-)      >        some international networks not yet support embedded RP.  
Campuses are
-)      >       pretty far behind.  NYU is one of the few that has done v6 
multicast
-)      >       with NYSERNet.  In the first ever v6 multicast hands on 
workshop in
-)      >       Albuquerque a few months ago, we viewed content that was 
being multicast
-)      >       from Syracuse.
-)      >      
-)      >       Put it in a product and I'll have an excuse to replace my 
Vbrick 1200's:-)
-)      >      
-)      >       /a
-)      >      
-)      >       Richard Mavrogeanes wrote:
-)      >       > I'd like to explore this group's experience with IPV6 
multicast, in particular, what do we believe is the current state of the 
Internet2 backbone network and what do we think is the state of enterprise 
routers and switches to allow it?
-)      >       >
-)      >       > Looking forward to an interesting thread...
-)      >       >
-)      >       > /rich
-)      >       >
-)      >      
-)      >
-)      
-)      
-)      --
-)      -------------------------------------------------
-)      Joel Jaeggli 
()
-)      GPG Key Fingerprint:
-)      5C6E 0104 BAF0 40B0 5BD3 C38B F000 35AB B67F 56B2
-)      
-) 
-)