I don't have enough information to express a judgement in this particular case, but I can say a few things about how one would go about analyzing questions of 'where should I put function [X]; in the host, or in the 'network' (which almost inevitably means 'in the switches')'. It seems to me that one has to examine three points: - What is the 'cost' to actually _do_ the thing (which might be in transmission usage, or computing power, or memory, or delay), in each alternative; these costs obviously generally cannot be amortized across multiple similar transactions. - What is the 'cost' of providing the _mechanism_ to do the thing, in each alternative. This comes in three parts. The first is the engineering cost of _designing_ the thing, in detail; this obviously is amortized across muiple instances. The second is _producing_ the mechanism, in the places where it is needed (for mechanisms in software, this cost is essentially zero, unless it needs a lot of memory/computes/etc); this is not amortized across many. The third is harder to measure: it's complexity. This is probably a book by itself, but it has costs that are hard to quantify, and are also very disparate: e.g. more complex designs are more likely to have unforseen bugs, which is very different from the 'cost' that more complex designs are probaly harder to evolve for new uses. So far I haven't said anything that isn't applicable across a broad range of information sytems. The last influence on where one puts functions is much more common in communication systems: the Saltzer/Clark/Reed 'End-to-end Arguments in System Design' questions. If one _has_ to put a function in the host to get 'acceptable' performace of that function, the operation/implementation/design cost implications are irrelevant: one has to grit one's teeth and bear them. This may then feed back to design questions in the other areas. E.g. the Version 2 ring at MIT deliberately left out hardware packet checksums - because it was mostly intended for use with TCP/IP traffic, which provided a pseudo-End-to-End checksum, so the per-unit hardware costs didn't buy enough to be worth the costs of a hardware CRC. (Which was the right call; I don't recall the lack of a hardware checksum ever causing a problem.) And then there's the 'techology is a moving target' point: something that might be unacceptably expensive (in computing cost) in year X might be fine in year X+10, when we're lighting our cigars with unneeded computing power. So when one is designing a communication system with a likely lifetime in many decades, one tends to bias one's judgement toward things like End-to-End analysis - because those factors will be forever. Sorry if I haven't offered any answer to your initial query: "having the switch do some of the call validation ... sounds like it takes load off the host", but as I have tried to explain, these 'where should one do [X]' questions are very complicated, and one would need a lot more detail before one could give a good answer. But, in general, "tak[ing] load off the host" doesn't seem to rate highly as a goal these days... :-) :-( Noel