Re: Multicast on 21CN

Mark wrote:
On Sun, 16 Mar 2008 19:08:40 GMT, "DAB sounds worse than FM"
<dab.is@dead> wrote:

The first article on

http://www.samknows.com/broadband/

says at the bottom:

"The afternoon was wrapped up with a proof of concept demonstration
of video content distribution in the 21CN network. Using Assured
Rate QoS, BT showed how content could be distributed from the core,
from one of their 20 aggregation points or from the MSANs themselves
(which will be present in
all exchanges in the UK). Distribution at this level is made
possible by
using multicast, which is not available on the current BT IPStream
product range."

Could someone say whether what BT is doing will fix the problem
PlusNet describes on its blog entry below (I think it does, because
it says that multicast can be distributed from the different levels
of the 21CN, and PlusNet says that they want it split further down
the line):

http://community.plus.net/blog/2008/02/28/how-uk-isps-are-charged-for-broadband-the-cost-of-ipstream/

"The same thing applies with multicast. Multicast can be used to more
efficiently distribute content. A number of customers wanted to
watch the
same video stream then using multicast rather than there being one
stream
per customer between the content provider and the end user, where the
network paths are the same there only needs to be one stream. At the
moment
on IPStream that would mean that if you were watching a multicast
stream
there would only need to be one stream between the content provider
and the ISP's network and it splits into multiple feeds at central
pipes.

Which of course is the major problem with using multicast at the
moment, the only cost saving to the ISP is the transit and/or
peering costs, which as we've seen above may not represent any real
savings or at best only a tiny
reduction because you still have one stream per customer going
across the central pipes.

For multicast to be successful in the UK the stream must be split
further
down the line, preferably at the BT PoP but at the very least at the
local exchanges. This is something we might see as part of BT's 21st
Century
Network upgrades which are taking place over the next few years."

The way I read it, it doe fix the problem. Frankly it would be
pointless to build a NGN like 21CN that didn't.


I agree, but just on Friday I was searching for info on whether the 21CN
would support multicast and the only mention I could find anywhere was on a
Griffin Internet web page which said it was "on the roadmap", and PlusNet
didn't seem too sure on their blog either. Anyway, at least they've
demonstrated it.

How long do you reckon it might be before BT actually launches it?

Tiscali's chief exec says their network support multicast as well, BTW:

http://networks.silicon.com/broadband/0,39024661,39170118,00.htm?r=2


Multicast has to work from head-end (wherever that is) through to the
user (a set-top box for example) in order to save aggregation network
bandwidth for applications like IPTV.


Yep. The BBC is launching its multicast radio streams as well:

http://www.bbc.co.uk/blogs/radiolabs/2008/03/streaming_radio_online_your_co_1.shtml

"Ashley Brown asks "Will BBC Radio be getting multicast and MP3 streams?" -
not only will we be getting multicast streams, we've actually had them for a
number of years"

I'd imagine the TV channels multicast streams will launch as well once the
fuss about the iPlayer bandwidth has died down a bit...


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

The adoption of DAB was the most incompetent technical
decision ever made in the history of UK broadcasting:
http://www.digitalradiotech.co.uk/dab/incompetent_adoption_of_dab.htm


.

Relevant Pages

  • Re: Multicast > 5-10 years time?
    ... Depends how well the implementation of multicast and network topology ... Yes it should be more efficient for the ISP. ... a multicast service automatically deploys as a single stream to ...
    (alt.radio.digital)
  • Re: Quality of BBC Internet radio to overtake DAB
    ... because current Wi-Fi radios don't currently support ... multicast, but all it needs is for them to write a bit of software ... network and router killer. ... want to continue receiving the stream, and if a timeout period expires ...
    (alt.radio.digital)
  • Questions about multicasting
    ... enabled internet backbone is called Mbone, ... Multicast adds a 10% overhead approximately to the ... We currently stream our radio station ... This takes up 300k of bandwidth ...
    (microsoft.public.windowsmedia.server)
  • Re: Multicast on 21CN
    ... Distribution at this level is made possible by using multicast, which is not available on the current BT IPStream product range." ... A number of customers wanted to watch the same video stream then using multicast rather than there being one stream per customer between the content provider and the end user, where the network paths are the same there only needs to be one stream. ... I remember the time when BT left routing on so stuff on the BT network didn't transit the ISPs at all.. ...
    (uk.telecom.broadband)
  • Multicast on 21CN
    ... Distribution at this level is made possible by ... using multicast, which is not available on the current BT IPStream product ... same video stream then using multicast rather than there being one stream ... network paths are the same there only needs to be one stream. ...
    (uk.telecom.broadband)