Vadim, I think we are accidently cross-wired..... I agree 100 percent that real-time data cannot be guarenteed over public networks. There is little benefit to discuss .999999s over public networks. My point was to point out that there are applications for real-time packet services where RSVP does not meet the requirements and neither does ST-II (who tunnels IPv5 over a public network and does any real-time work ??... none to my knowledge!) In my previous posts on this thread today, I intentionally did not mention public networks; sorry I did not specifically state the word 'private' . I assumed that Everyone in Networking knows that .9999++ delivery over public networks was not what I was discussing. Hopefully the confusion is clear.... when I mention real-time data services, I am talking private datagram services, not public. Best Regards, Tim