Re: Multicast on 21CN



"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.




.

Relevant Pages

  • 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
    ... of video content distribution in the 21CN network. ... it says that multicast can be distributed from the different levels ... If BT do multicast in the DSLAM then the ISPs are getting something ...
    (uk.telecom.broadband)
  • Re: Multicast > 5-10 years time?
    ... multicast and therefore it was hogging BBC bandwidth!). ... I take it that the ISPs can implement multicast so that there's only ... stream to the lowest common point in the network where it finally ...
    (alt.radio.digital)
  • 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)
  • 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)