Multicast Internet Route table.

Justin M. Streiner streiner at
Tue Sep 2 13:29:23 UTC 2014

On Tue, 2 Sep 2014, Corey Touchet wrote:

> 14 years at Verizon Wireless and I despised the crop of multicast products
> that seemed to pop up from time to time.  Even in a fully controlled
> network multicast remains at best black magic.  There are ways to make it
> more reliable and prevent people from ruining the setups especially for
> PIM type setups, but I would agree with others, unicast has better
> advantages though you have to keep up with the bandwidth curve.

I can tell you that the IPv4 multicast routing table size has been 
pretty much flat (stable to declining slightly) for the past several 
years.  Right now, I see a total of just under 3,800 IPv4 multicast routes 
through Internet2 and other research/education networks, and that number 
hasn't changed much in probably 2-3 years.  I don't get any multicast 
routes from my commodity Internet providers.  Several years ago (2008-ish),
I was receiving around twice that many multicast routes, so it has died 
off significantly in the long view.

External IPv4 multicast traffic has been pretty much zilch for quite some 
time, from my viewpoint.


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