On Sat, Jun 22, 2013 at 05:33:17PM +0200, Emmanuel Thierry wrote: > Hello, >
Hello, > >> You can argue that in this example the second session is invalid anyway > >> since it tries to use IPv6, but more important that it hasn't been > >> closed after the first one succeeded. Returning to the beginning of the > >> question, what would happen if they're both valid? > > > > It's not 2 connections for the same message, it's 2 connections for > > the same relay. The message is eventually handled by one of the > > connection. > > > > What happens here is that there is a mail to be sent to a certain > > domain, the MTA resolves the MX list, which turns out to contain an > > IPv6 and IPv4 address. It starts a new connection on the first, and, > > after a while, on the second. The idea is that if the second is > > reachable immediatly, we don't have to wait for the first one to > > timeout if we can send the message on the second. So after having > > sent the message the second connection closes since there is nothing > > left to do. And later, the first connection attempts times out. > > > > By the way it's not far from what is proposed by the RFC 6555: > http://www.rfc-editor.org/rfc/rfc6555.txt. > There exists a very good explanation of this RFC and the reasons to do that > by St?phane Bortzmeyer (for french speakers): > http://www.bortzmeyer.org/6555.html > It's funny that you mention RFC 6555 :-) Someone from this list mentionned it to me off-list a while ago and back then I read it without paying attention because I'm not a real ipv6 user and it usually annoys me to deal with it (yeah i know it's bad...) At a hackathon, we discussed a particular ipv6-unrelated issue when some host as multiple routes and we came up with this solution which Eric has implemented. The fact that it works fine with dual-stack hosts is really a side-effect of our solution more than a feature we really wanted ;-) -- Gilles Chehade https://www.poolp.org @poolpOrg -- You received this email because you are subscribed to mailing list: [email protected] To unsubscribe, send mail with subject: [[email protected]] unregister
