Maybe we can consider this topic (anycast in content download and DNS) in another angle. For content download, the focus is throughput, and the freezing time caused by the anycast interruption is OK since the freezing time (which is usually several or tens or hundreds of milliseconds) can be omitted compared with the whole content download time which may be several or tens of minutes. While for DNS, the focus is the latency but not throughput, and the freezing time cannot be omitted since one normal DNS resolution latency is usually one RTT. So DNS is different from other applications like content download in the traffic pattern and QoS (Quality of Service) metric.
Guangqing Deng CNNIC From: Tony Finch Date: 2015-04-28 19:34 To: Phillip Hallam-Baker CC: Warren Kumari; [email protected]; Christian Huitema; Paul Hoffman Subject: Re: [dns-privacy] DPRIVE over UDP or TCP Phillip Hallam-Baker <[email protected]> wrote: > On Tue, Apr 28, 2015 at 5:04 AM, Tony Finch <[email protected]> wrote: > > Phillip Hallam-Baker <[email protected]> wrote: > >> > >> Having it work for content and DNS are two different things. The > >> routing tables only need to be constant for a few minutes to support > >> TCP content download. For DNS to be viable they have to be stable much > >> longer. > > > > Why? > > The byterange extensions in http mean that it is possible to resume a > session interrupted part way through if it is static content. Most HTTP interactions aren't resumable in this way, so this observation does not suggest to me that HTTP needs less routing stability than DNS. > If the anycast changes then you are going to have to timeout and resume. This is also true for HTTP. I still don't see why DNS needs more routing stability than HTTP. Tony. -- f.anthony.n.finch <[email protected]> http://dotat.at/ Rockall, Malin, Hebrides, Bailey: West or northwest, becoming cyclonic 5 to 7, occasionally gale 8, except in Hebrides. Rough or very rough, occasionally high at first in Bailey. Rain or showers. Good, occasionally moderate. _______________________________________________ dns-privacy mailing list [email protected] https://www.ietf.org/mailman/listinfo/dns-privacy
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