brandon@rd.bbc.co.uk (BrandonButterworth) writes:
If MBONE is to be a serious contender the ISPs must deliver it, then us content providers that are wasting tons of net bandwith could become nicer netizens and wouldn't use the unicast products that end users are asking for. Of course the ISPs may not take as much money off us as we wouldn't need quite so much bandwidth (perhaps there's a reason there?)
The real problem is that IPv4 Multicast scales badly with the number of groups, and Multicast routing is difficult. If you doubt any of this, kindly review the recent Dave Meyer presentations at any of your favourite conferences. Content multicast is *wonderful* news for any ISP that overbooks its backbone capacity: the amount of overbooking possible increases with the volume of highly-popular scheduled content. That is, if you have lots of replication happening in multicast routers (presumably because your customers have things attached to them who want the same content at the same time), then you can fill your customer links with stuff that has less impact on your relatively large backbone pipes. InternetMCI is among a number of ISPs who have worked on eliminating redundant copies of multicast traffic crossing their backbones by deploying MBONE infrastructure. This is not the same as deploying a multicast infrastructure, however that is a very different rant. So, frankly, your suggestion that ISPs make less money off you when there is lots of well-laid-out distribution trees carrying lots of content to lots of places is simply wrong. The problem is mostly that people are busy making unicast mostly work and are finding that sufficiently difficult that making multicast work better than it does now just does not get attention, particularly since multicast routing is hard and multicast routing code is buggy at least in part due to that. The lack of perceived utility for multicast also has an effect on the other side of a cost-benefit analysis that does not favour rapid deployment. Sean.