Questions about multicasting

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Date: Sat, 10 Apr 2004 23:51:24 -0700

I will try to answer a few.

1. Yes.
2. I don't have numbers, but my *guess* is that a large
part of the internet users would probably be left out in
your scenario because they are likely to have a non-
multicast-enabled router in the middle. The multicast
enabled internet backbone is called Mbone, you may want
to search for this on the internet and find out how
extensive it is.
3. Multicast adds a 10% overhead approximately to the
bitrate, so just add 10% to your calculations and you are
right.

Ravi

--
This posting is provided "AS IS" with no warranties, and 
confers no rights.
>-----Original Message-----
>Ok, several questions here for those more in the know...
>
>We are considering offering subscription based services 
from our site. One of the extras subscribers would 
receive would be full access to several live A/V streams. 
We currently stream our radio station (irieradio.com) 
using WMS9. Our current video streaming, aside from 
having no sound, is coming from some low end security 
servers. We want to up the quality of the output, and 
increase what we're giving to people (# of streams). 
Content is king.
>
>So, my boss (in his genius [dripping sarcasm here]) 
suggested this idea to the big boss without thinking it 
through. Our site had roughly 150,000 unique users with 
2+ mil page views last year. This isn't huge by some 
standards, but with roughly 1800 people concurrently 
trying to pull a stream down the bandwidth would become 
excessive (even beyond the fractional DS3 we just signed 
for). So, after a few days and sleepless nights of study 
(I have 45 days to make this happen) I've finally come up 
with some possible answers and several more questions.
>
>The WM help docs state that multicast works in such a 
manner: Your encoder sends a signal to WMS (say 300kbps 
for argument's sake). WMS broadcasts a multicast signal 
to a multicast address. This takes up 300k of bandwidth 
regardless of how many connect to your multicast stream. 
You must have a multicast enabled router and a multicast 
IP address.
>
>1)    Does this sound right?
>2)    What percentage could I possibly expect (of my 
user base) who would not be able to connect to the 
multicast stream because somewhere between us their is a 
non-multicast enabled router?
>3)    So If I put out 6 separate 300kbps streams then it 
would only take approximately 1.8M of my bandwidth? (this 
would not include bandwidth taken up by those connecting 
via the unicast rollover because they aren't multicast 
enabled somewhere along the way)
>4)    Is there a formula out there, somewhere, that can 
tell me what size processor(s)/ram/harddrive (no 
archiving) might be necessary to run a single stream? 
Multiple streams?
>5)    What other special considerations might I need to 
look at here? (I believe I read that I have to use MS2003 
Emterprise Edition to publish the multicast stream...)
>
>Any help is greatly appreciated and TIA
>
>Cutter
>.
>

• Previous message: Ravi Raman: "wms 9 credentials and authentication"
• In reply to: cutterbl: "Questions about multicasting"
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