Sunday traffic curiosity

Sun Mar 22 19:43:48 UTC 2020

On Sun, 22 Mar 2020 19:17:59 +0000
Grant Taylor via NANOG <nanog at nanog.org> wrote:

> What was wrong with Internet scale multicast?  Why did it get abandoned?

There are about 20 years of archives to weed through, and some of our
friends are still trying to make this happen.  I expect someone (Hi
Lenny) to appear any moment and mention AMT.  So my take isn't
universally accepted, but it won't be too far from what you'll hear
from many. Brief summary off the top of my head:

1. Complexity.  Both in protocol mechanisms and the requirements in
network devices (i.e. snooping, state, troubleshooting).

2. Security. Driven in part by #1, threats abound.  SSM can eliminate
some of this and you can design a receiver-only model that removes most
of the remaining problems - congratulations you just reinvented over
the air broadcast TV.  Even if you don't do interdomain IP multicast,
you still may be at risk:

  <https://ccronline.sigcomm.org/wp-content/uploads/2017/01/p27-sargent.pdf>

3. Need and business drivers.  Still far from compelling to build and
support all this to make it worthwhile for all but a few niche
environments.

Support and expertise in this area is also very thin.  Your inquiry
demonstrates this.  I stopped teaching it to students.  What remains is
becoming even less well supported than it has been.  There is almost no
interdomain IP multicast monitoring being done anymore.  There is scant
actual content being delivered, all the once popular stuff is gone.
The number of engineers who know this stuff are dwindling and some that
do know something about it are removing at least some parts of it:

  <https://tools.ietf.org/html/draft-ietf-mboned-deprecate-interdomain-asm-07>

John