Re: Sunday traffic curiosity

[Alexandre Petrescu <alexandre.petrescu () gmail com>]

Le 22/03/2020 à 21:31, Nick Hilliard a écrit :
> Grant Taylor via NANOG wrote on 22/03/2020 19:17:
> > What was wrong with Internet scale multicast?  Why did it get abandoned?
>
> there wasn't any problem with inter-domain multicast that couldn't be 
> resolved by handing over to level 3 engineering and the vendor's 
> support escalation team.
>
> But then again, there weren't many problems with inter-domain 
> multicast that could be resolved without handing over to level 3 
> engineering and the vendor's support escalation team.
>
> Nick

For my part I speculate multicast did not take off at any level (inter 
domain, intra domain) because pipes grew larger (more bandwidth) faster 
than uses ever needed.  Even now, I dont hear problems of bandwidth from 
some end users, like friends using netflix.  I do hear in media that 
there _might_ be an issue of capacity, but I did not hear that from end 
users.

On another hand, link-local multicast does seem to work ok, at least 
with IPv6.  The problem it solves there is not related to the width of 
the pipe, but more to resistance against 'storms' that were witnessed 
during ARP storms.  I could guess that Ethernet pipes are now so large 
they could accomodate many forms of ARP storms, but for one reason or 
another IPv6 ND has multicast and no broadcast.  It might even be a 
problem in the name, in that it is named 'IPv6 multicast ND' but 
underlying is often implemented with pure broadcast and local filters.

If the capacity is reached and if end users need more, then there are 
two alternative solutions: grow capacity unicast (e.g. 1Tb/s Ethernet) 
or multicast; it's useless to do both.  If we cant do 1 Tb/s Ethernet 
('apocalypse'  was called by some?) then we'll do multicast.

I think,

Alex, LF/HF 3