On 2/11/2013 11:05 PM, Tim Durack wrote:
Multicast is dead. Feel free to disagree. :-) Tim:>
Multicast is a vendor selling point, as you essentially need a coherent end-to-end solution to get it to work PROPERLY. Of course if it does not work PROPERLY, it will still largely work, albeit inefficiently, in most cases other than routed multicast. So personally I'd love to see the multicast environment die as well :) It's so... well... decades old stuff. For cable / IPTV it may fly and scale, but there is a decided move to the on-demand model. And even with live broadcast, there's the growing DVR selling point of "pause and resume" which is buffering and unicast, just localized to the set top box. It is also the opposite of "on demand" as multicast only works on a synchronized timeline. Few if any people will demand a specific item "on demand" at the same time, or even within a reasonable time window for a buffered/staged multicast (..."this channel should be available shortly..."). You could multicast to cache boxes, but that is prone to cache hit randomization, and only useful to "pre-populate" an incident. Multicast still works for live broadcast. And can be convoluted to work in odd/mixed topologies (e.g., Octoshape... hideous thing). But working multicast requires tweaking (PIM, IGMP snooping, CGMP/etc vendor-specific L2 pruning) that makes it ugly. We had enough headaches just trying to route multicast computer imaging traffic (Ghost, SCOM, etc) that I couldn't imagine trying to extend that out into userland without some serious forklift upgrades to insure it would work at the hardware level. Locally, knock y'erself out with fingers crossed, you'll only nuke your broadcast domain, but routing it? Jeff