Re: Multicast on 21CN

dennis@home wrote:
"DAB sounds worse than FM" <dab.is@dead> wrote in message
news:YeeDj.21323$kN5.7939@xxxxxxxxxxxxxxxxxxxxxxx
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."

Demonstrated that to BT more than three years ago!


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):

The system I demonstrated could split the multicast down to the DSLAM
level.. I see no reason why BT can't do that as their exist DSLAMS
can with little modification if any.


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."

BT could do it now.. its a case of who is going to pay.
If BT do multicast in the DSLAM then the ISPs are getting something
for nothing.
I remember the time when BT left routing on so stuff on the BT network
didn't transit the ISPs at all.. what did the ISPs do.. setup VPNs
and stuff like that to avoid their pipes and hence the charges.. BT
stopped this by forcing all the data up the ISPs pipe by
encapsulating it early on and putting it in tunnels to the ISP.


One option talked about was adding storage in the DSLAM to buffer
video streams for interactive playback.. ATM you have to go back to
the central server which limits the number of customers per DSLAM
that can have interactive video.. buffering it takes advantage of the
fact that many will be watching the same football match or eastenders
so you can get more customers doing interactive.


I don't think BT would have demonstrated video over multicast on the 21CN to
journalists last week if they weren't going to use it.

There's also the competition element, because Virgin Media will be adding
support for multicast at the same time as it launches its 50 Mbps broadband
package, and Tiscali's network is designed to support multicast. That's 2
out of the 4 biggest ISPs supporting it, and the other LLU ISPs could
support it as well if they wanted to.


--
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 on 21CN
    ... so that the ISPs would stand to save ... of video content distribution in the 21CN network. ... Distribution at this level is made possible by using multicast, ... The BBC carrot approach may help (the streams over multicast are ...
    (uk.telecom.broadband)
  • Re: Multicast on 21CN
    ... so that the ISPs would stand to save ... this level is made possible by using multicast, ... How does their network support the traffic when we're limited to puny bit rates and if we want anything more the world will end? ... They have plenty of bandwidth though.. ...
    (uk.telecom.broadband)
  • Re: Multicast on 21CN
    ... of video content distribution in the 21CN network. ... it says that multicast can be distributed from the different levels ... watch the same video stream then using multicast rather than there ... If BT do multicast in the DSLAM then the ISPs are getting something ...
    (uk.telecom.broadband)
  • Re: Multicast on 21CN
    ... so that the ISPs would stand to save ... of video content distribution in the 21CN network. ... this level is made possible by using multicast, ...
    (uk.telecom.broadband)
  • 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)