Re: [MBONED] ipv4 multicast address ranges, actual usage.

[Leonard Giuliano <[e-mail]>]

Well articulated, Jake.

Dave- Keep in mind, outside of 224/8, all the space is derived and 
designed to *reduce* wasted allocations.  That is, 239/8 is basically like 
RFC1918 for mcast and to be used to prevent use of public space for 
internal network usage.  233/8 and 234/8 were designed to end the static 
IANA allocations for mcast addressing.  And 232/8 will hopefully make all 
the other allocations unnecessary.


On Wed, 18 Dec 2019, Holland, Jake wrote:

| Hi Dave,
| 
| I think the framing of "actual usage" isn't quite the best way to look
| at it.
| 
| Much like ECN and IPv6, there were some hurdles and it took longer than
| anyone hoped, but it's not dead yet, the reasons to use it are still
| with us, and there has been recent movement that's giving some cause
| for hope that the next few years might see a much expanded deployment.
| (Any day now...)
| 
| With that said:
| 
| 232/8 is extremely important, from my point of view.  I'd also be
| slightly reluctant to give up 233 or 239, though I care much less
| about them than 232.
| 
| The rest of the space I have no attachment to.
| 
| Reasons:
| 
| ASM for interdomain is in process of getting deprecated:
| https://urldefense.com/v3/__https://tools.ietf.org/html/draft-ietf-mboned-deprecate-interdomain-asm-03__;!!NEt6yMaO-gk!RlZVVsFmvI2wdvncPQPyASqr6B46tqgFJJ79SMTgIx93uDo4JS38PyGdO88geEU$ 
| 
| But SSM is still the way of the future, with any luck, and the 232/8
| allocation is critical to its usability.  (The flexibility on 233 and
| 239 that makes them candidates for extra SSM space is also the biggest
| part of what I like about them.)
| 
| My deployment is still pretty limited today, but a couple of my recent
| drafts are trying to get it over a few final hurdles:
| https://urldefense.com/v3/__https://tools.ietf.org/html/draft-ietf-mboned-driad-amt-discovery-10__;!!NEt6yMaO-gk!RlZVVsFmvI2wdvncPQPyASqr6B46tqgFJJ79SMTgIx93uDo4JS38PyGdj2arhgA$ 
| https://urldefense.com/v3/__https://tools.ietf.org/html/draft-jholland-mboned-dorms-00__;!!NEt6yMaO-gk!RlZVVsFmvI2wdvncPQPyASqr6B46tqgFJJ79SMTgIx93uDo4JS38PyGdGwB4rSI$ 
| (plus a couple of augmentations to dorms that try to enable a safe
| MulticastReceiver W3C API.)
| 
| Once these hurdles are solved, it's my sincere hope to start rolling out
| interdomain usage of 232/8 at as big a scale as I can muster.  (I have a
| few trickles available today, but "actually used" for interdomain traffic
| is still a bit of a stretch.)
| 
| Provided that SSM is left alone, I have no objections that are
| specifically about reassigning unused multicast address space.  (For
| this venue, I'll leave aside any questions about the overall wisdom of
| the project... :) )
| 
| Best,
| Jake
| 
| 
| On 2019-12-18, 13:02, "Dave Taht" <[e-mail]> wrote:
| 
| On Wed, Dec 18, 2019 at 12:49 PM Leonard Giuliano <[e-mail]> wrote:
| >
| > Dave,
| >
| > Take a look at RFC6308 and RFC 5771 for an overview of multicast
| > addressing.  But to summarize, 232/8 is reserved for SSM (RFC4607).
| > 233/8 is reserved for GLOP (RFC3180).  234/8 is reserved for
| > Unicast-Prefix-Based Allocation (RFC6034).  239/8 is reserved for admin
| > scoped allocation (RFC2365).
| 
| I had already reviewed those pretty thoroughly in writing the drafty draft.
| 
| The question was:
| 
| "to what extent are the various allocations in the 232/8 to 238/8
| range actually used today, and for
| what?"
| 
| The "for what" portion of the question was: what applications today
| actually use GLOP? or RFC6038? or SSM?
| 
| What mailing list or list might have some answers to the actual usage
| of these ranges?
| 
| As best as I can tell actual multicast usage of ipv4 is down to the
| dozens of applications (all with allocated ip address in 224 or 239 -
| with mdns topping the list.
| >
| > Hope this helps,
| > Lenny
| >
| > On Wed, 18 Dec 2019, Dave Taht wrote:
| >
| > | As a few people know I've been working (quixotically) in my spare time
| > | towards making more of the IPv4 address space generally usable. We've
| > | landed patches for 0/8 in linux, and 240/4 had already been mostly
| > | made working a decade back.
| > |
| > | Now we come against a harder problem, in that 1) - a vast swath of
| > | multicast address space was never allocated for anything by iana
| > | (225/8-231/8) and 2) 232/8-238/8 appears severely underutilized. Only
| > | portions of 224/8 and 239/8 seem to have any usage at all.
| > |
| > | We've successfully made that first formerly multicast range pretty
| > | generally usable in a string of patches on our github for various oses
| > | and routing daemons. https://github.com/dtaht/unicast-extensions - and
| > | for a drafty draft of a draft internet draft, see:
| > | https://github.com/dtaht/unicast-extensions/blob/master/rfcs/draft-gilmore-taht-v4uniext.txt
| > |
| > | My question today, though (lacking finding a mailing list more
| > | suitable than this - is there one?), is to what extent are the various
| > | allocations in the 232/8 to 238/8 range actually used today, and for
| > | what?
| > |
| > |
| > | --
| > | Make Music, Not War
| > |
| > | Dave Täht
| > | CTO, TekLibre, LLC
| > | https://urldefense.com/v3/__http://www.teklibre.com__;!!NEt6yMaO-gk!ToLvTOd6t8dQ1-sH4XmghgDQrcb4JVFwnxuPeA-h4IwQmqxaVhSKHdAeEcHC_4g$
| > | Tel: [phone]
| > |
| > | _______________________________________________
| > | MBONED mailing list
| > | [e-mail]
| > | https://urldefense.com/v3/__https://www.ietf.org/mailman/listinfo/mboned__;!!NEt6yMaO-gk!ToLvTOd6t8dQ1-sH4XmghgDQrcb4JVFwnxuPeA-h4IwQmqxaVhSKHdAe8DjJ-24$
| > |
| 
| 
| 
| -- 
| Make Music, Not War
| 
| Dave Täht
| CTO, TekLibre, LLC
| https://urldefense.com/v3/__http://www.teklibre.com__;!!NEt6yMaO-gk!RlZVVsFmvI2wdvncPQPyASqr6B46tqgFJJ79SMTgIx93uDo4JS38PyGdRWcS0UY$ 
| Tel: [phone]
| 
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