OK, so the title is meant to be a bit ambiguous, as much a question as it is a statement--I’d love to hear your thoughts on this. I have been pondering this a bit since I am prepping for my CCIE re-cert and its kinda fun looking back at how much things have changed in 15 years. It also seems everyone and their brother wants to sell Ethernet switches these days. Companies that have never sold Ethernet are now all over it and companies that have repeatedly walked away from the Ethernet market keep coming back. So, what is it about Ethernet that makes it the networking juggernaut? A lot is always made about the economics of Ethernet, but saying Ethernet wins because it is cheaper is a little too simplistic--hey, LocalTalk was cheap, but you see where that went. Instead, I think Ethernet continues its success because it manages to stay the most cost-effective solution. How does this happen? The first reason is that Ethernet has proven to be infinitely extensible--over the last couple of decades we have managed to incrementally evolve Ethernet to successfully support demanding traffic such as voice, video, and now storage. At the same time, you can get speeds from 100Mb Ethernet to 10Gb Ethernet and in a couple of years, 40Gb and 100Gb Ethernet. So, one secret seems to be that Ethernet offers just-in-time innovation--you don’t have have to buy more capacity or capability than you really need without worrying about investment protection. The corollary for this is that you don’t end up paying for innovation that you don’t want or need, yet you get to benefit from economies of scale created by those who do. In 2006, a 10GbE port on a modular chassis had an ASP of $4,667 and about 226,000 ports were sold to folks who needed them. The volume over the intervening years has given vendors the scale they need to bring down the forecasted ASP for this year to $2,606 with a forecasted volume of 762,000 ports (by the way, these numbers are all vendors, worldwide, courtesy of Dell’Oro).I think the second factor is what I call familiarity. While, every once in a while, someone will announce a new protocol or technology that is interesting, a cool technology, by itself, is seldom compelling. Ethernet represents a comprehensive solution--a well understood technology with a broad selection of operations and management tools and an immense body of operational expertise behind it. In short, its a known quantity. New technologies suffer from this catch-22: a lack of this kind of ecosystem is an inhibitor to adoption, but the ecosystem will not get built unless customers are willing to take the risk with a new, unproven technology, which, these days, most folks are not. You would think perhaps there is some opportunity to build a beach head in a tightly focused area, but even that does not seem to be the case. Take the case of the Top 500 Supercomputing sites--you would think this is a stronghold for a protocol like Infiniband, but 56% of the top 500 sites are using Ethernet, roughly twice as many as are running Infiniband, and the use of Ethernet seems to be increasing.Finally, I’ll toss our the use of unshielded twisted pair (yeah, I know LocalTalk ran over twisted pair too). Having been personally traumatized by the nightmare known as Thinwire Ethernet. 10-BaseT and its UTP based cousins provide a physical layer that is cheap, easy to install and reliable. I think the days of copper are numbered in the data center, but I think it will continue to rule in the campus, and, in any case, UTP is representative of Ethernet’s reputation as a low-maintenance protocol. By default, Ethernet tends to just work--you take a couple of switches, some random hosts, and some RJ45 patch cables and hand them over to my 11 year-old and you will have a functioning network in about as much time as it takes to cable everything together and power it on.While there are a whole host of factors behind Ethernet’s success, these are top of mind for me right now--agree, disagree, what did I miss?