On Nov 1, 2013, at 3:46 PM 11/1/13, Erik Kline <[email protected]> wrote:
> I'm not sure what you mean by "impact". Sorry for the lack of clarity. You answered my question - the different behaviors are strictly correlated to the version of OS 10 and are independent of the version of Safari. - Ralph > > Different OS versions do seem to behave differently. I think 10.7 is > when the dueling connections implementation was introduced, and it did > drop Safari's IPv6 native preference by basically half. And if you > think about it, in a perfect network where IPv4 and IPv6 have > identical performance each would likely only be used ~50% of the time. > > It looks like you would basically need to penalize IPv4 in order get > your IPv6 ROI, *if* all your customers ever do is surf the web using > Safari on recent Macs to do so. The total impact of an HE > implementation is obviously in proportion to its use for web traffic. > > Let me revise the numbers for this sample network. I was including > measurements where the client may not have asked for any AAAAs, so let > me restrict my numbers just to measurements where AAAAs were > requested. That's what I get for not waiting to have my stats-diving > be peer reviewed (different timezone, etc). > > "Once more, with feeling!", and I'm sure Lorenzo and correct me later on. > > [All MSIE] > no HE, later versions do a simple reachability check ~once > 96% IPv6 native preference > 7ms average extra latency > > [All Chrome] > HE: 300ms lead for IPv6 then fallback to IPv4 > 83% IPv6 native preference > 1.5ms average latency improvement over IPv4 > > [All Safari + 10.6] > I think no HE? (it's been so long...) > 97.5% IPv6 native preference > 0ms average latency delta between IPv4 and IPv6 > > [All Safari + 10.7,10.8, and 10.9] > HE: strict connection racing, at one point A record requested > first, I believe > 48% IPv6 native preference > 9ms average latency improvement over IPv4 (by design, working as > intended, etc.) > > So the HE implementation does matter. In this particular sample > network I'm guessing that there may be about an extra 7-8 ms for IPv6 > requests to Google (this is end-to-end, so the sources of latency > could be multiple including whether or not the interconnect paths for > IPv4 and IPv6 are the same). > > Lastly, I am attaching an old slide from a measurements presentation > we gave at the V6 World Congress in Paris in the very beginning of > this year wherein I attempted to graphically illustrate the effect of > different HE implementations. > <Finicky Eyeballs.png>
