Confirming source-routed multicast is dead on the public Internet

Saku Ytti saku at ytti.fi
Wed Aug 1 16:24:21 UTC 2018


Hey Mankamana,

> other than billing problem, is there any other reasons why multicast would not be viable for public internet ?

Imagine someone like youtube or netflix would like to use multicast,
instead of caches. They'd need to start new multicast stream for every
content with small delay (to get more viewers on given stream), how
much delay would consumer tolerate before content starts? 1min? 5min?
So every minute or every 5 minute new stream of movie would be sent,
except it would need to be sent many times, for each bitrate
supported.
Each of these streams is wide (wider than unicast) HW state that needs
to be stored on every device on path, for unicast we only store 1
narrow HW state per destination, for multicast we store 1 wide HW
state per flow/stream, we don't have the hardware to do that, if there
would be any significant demand for multicast.
It only works when there is no use-case for it, and even then, it's
insecure DoS vector.

-- 
  ++ytti


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