On Thursday 12 February 2015 12:33:50 Thiago Macieira wrote: > On Thursday 12 February 2015 19:59:33 Etienne Sandré-Chardonnal wrote: > > Dear all, > > > > I have a client/server app written fully in Qt 4.8.5, running under > > Windows > > 7 64bit > > > > When the client tries to connect to the server over a local ethernet > > network in the same room. > > > > QTcpSocket::connectToHost returns almost immediately when using the IPv4 > > host address, while it takes nearly 22s with the IPv6 address. In both > > cases, the connection is successful and the communication works flawlessly > > (and fast). > > Also, if the client disconnects and reconnects, it's now very fast in both > > protocols. Only the first time is slow for IPv6 > > > > What can be the reason for this? I googled this without much success. > > Can you check the traffic sniffing for this? Is the initial TCP/IPv6 SYN > packet sent quickly? Or, instead, is the initiating host sending ICMPv6 > Neighbour Discovery packets trying to locate the destination on the > network?
Did you connectToHost to an IPv6 address or to a hostname that resolves to IPv6? If the latter, can you check if it's sending DNS requests that simply take long to reply? There are quite a few broken DNS servers out there that don't repond properly to AAAA queries. -- Thiago Macieira - thiago.macieira (AT) intel.com Software Architect - Intel Open Source Technology Center _______________________________________________ Interest mailing list [email protected] http://lists.qt-project.org/mailman/listinfo/interest
