Re: interop problems with getaddrinfo() address selection
Keith Moore <moore@cs.utk.edu> Sat, 08 December 2007 21:21 UTC
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Date: Sat, 08 Dec 2007 13:21:00 -0800
From: Keith Moore <moore@cs.utk.edu>
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To: Tony Finch <dot@dotat.at>
Subject: Re: interop problems with getaddrinfo() address selection
References: <Pine.LNX.4.64.0712061901020.24448@hermes-1.csi.cam.ac.uk> <200712062020.PAA16213@Sparkle.Rodents.Montreal.QC.CA> <Pine.LNX.4.64.0712071735070.24448@hermes-1.csi.cam.ac.uk>
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Cc: der Mouse <mouse@Rodents.Montreal.QC.CA>, discuss@apps.ietf.org
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Tony Finch wrote: > On Thu, 6 Dec 2007, der Mouse wrote: > >> I'm interseted in what sort of problems it causes. >> > > DNS round robin is effective at balancing load evenly across multiple > servers, because each client is (in effect) directed to one of the servers > at random. If the client sorts the DNS response before using it then the > randomization is defeated and the load on the servers is no longer > balanced. > this seems like an almost-inherent consequence of IPv6's expecting hosts to have multiple addresses and asking hosts initiating a communication to do address selection. it's not specific to getaddrinfo() - any API that tried to solve that problem would be likely to reorder addresses to some degree. though it should be possible for the client implementation to go through the list of addresses, assign a preference value to each one (based on address type and number of leading bits in common with one of the hosts's local addresses), then perform a stable sort by preference value.
- interop problems with getaddrinfo() address selec… Tony Finch
- Re: interop problems with getaddrinfo() address s… der Mouse
- Re: interop problems with getaddrinfo() address s… Tony Finch
- Re: interop problems with getaddrinfo() address s… der Mouse
- Re: interop problems with getaddrinfo() address s… Keith Moore
- Re: interop problems with getaddrinfo() address s… Tony Finch
- Re: interop problems with getaddrinfo() address s… Keith Moore
- Re: interop problems with getaddrinfo() address s… Tony Finch
- Re: interop problems with getaddrinfo() address s… der Mouse
- Re: interop problems with getaddrinfo() address s… Tony Finch
- Re: interop problems with getaddrinfo() address s… der Mouse
- Re: interop problems with getaddrinfo() address s… Keith Moore
- Re: interop problems with getaddrinfo() address s… Stephane Bortzmeyer
- Re: interop problems with getaddrinfo() address s… Tony Finch
- Re: interop problems with getaddrinfo() address s… der Mouse
- Re: interop problems with getaddrinfo() address s… Keith Moore
- Re: interop problems with getaddrinfo() address s… Keith Moore
- Re: interop problems with getaddrinfo() address s… Keith Moore
- Re: interop problems with getaddrinfo() address s… der Mouse
- Re: interop problems with getaddrinfo() address s… Tony Finch
- Re: interop problems with getaddrinfo() address s… Keith Moore