>>Multicast is necessarily a LOT weaker: >> >> 1) I can get a copy of packets by normal operation >> (join a group). there is no equivalent for UDP, >> notably for paths that aren't shared. Again, not in all cases. You over-simplify the effectiveness of scoping. You can't have it both ways. Yes, there is a situation where you can obtain a copy of a multicast packet through standard operation. But the fact that scoping and addressing make it non-trivial and the fact that "normal" operation doesn't prevent you from snooping UDP packets shrinks the gap from a "LOT" weaker. And as I said before, if data security is important, effectively there is no gap. >> 2) UDP has application, network, and tunnel encryption that >> is both widely deployed and widely used. there is >> no equivalent for multicast. I disagree... a number of commercial multicast apps have encryption. Don't try and argue now that some relative percentage of multicast apps have less encryption than unicast apps. You're comparing a protocol that has been around a lot longer than multicast and trying to make an apples-to-apples comparison based on less availability. And for the record, multicast is UDP. -Kevin
