Actually I have run both packet-switched and IP-based (as well as mixed) networks, with end nodes and users numbering in the tens of thousands. I've also discussed this very topic with researchers who work on MPLS/DSCP technology for telcos like AT&T, for example. The consense is pretty much this: prioritizing packets on the Internet as it currently is built will result in only a small margin of improvement. Fanatisies about how it will significanly improve network performnace are just that - fantasies. While it won't degrade performance for tagged traffic, it also won't do very much to improve things. Again, this has to do the the hetrogenous nature of the Internet, as well as how IP routing itself works - different enough from how packet, cell, and voice based networks to make it inaccurate to draw accurate analogies by comparison. If each and every entity running equipment on the global internet isn't setting up their prioritizations in a compatible way, improvements resulting from prioritizing traffic will almost certainly not amount to enough to adequately address security or emergency concerns as they were framed in the original reference. And, of course if any content provider actually pays for traffic prioritization thinking to get consistant measurable results, they'll find they've paid for remarkably little. As for the deep packet inspection issue (although not particularily relevant), the deeper packets are inspected, the more likely that what little improvement actually prioritizing traffic has to offer will diminish even more. None of this is to say that prioritizing traffic will result in nothing. It'll certainly slow non-prioritized traffic down. That's because its easier to degrade network performance than it is to improve it from an IP prioritization point of view. So, in the end, it'll just slow people down, and occasionly improve other traffic in an unreliable way. It might seem to actually work at times, but don't count on it in a pinch. If people are looking to IP diffserv settings to address emergency needs, they're looking in the wrong place. The entire traffic prioritization play is an attempt to make it look as though more is being offered, when in fact no additional bandwith is being put into the setting - the only thing that will actually improve reliability in a consistant way. The one thing it will cost telcos hard dollars to do.