Date: Tue, 28 Aug 2012 17:38:55 +0200 From: Norbert Aschendorff <norbert.aschendorff@yahoo.de> To: freebsd-stable@freebsd.org Subject: IPv4 vs. IPv6 Ethernet Performance Message-ID: <503CE60F.8040007@yahoo.de>
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Hi, I'm using here a Gigabit Ethernet network and some UN*X machines, among others some Linux-based (Kernel 3.x) and one running FreeBSD 9.1-RC1. Using iperf (in TCP mode), the IPv6 bandwith between two Linux machines (directly attached to the same switch) is about 925 Mbit/s, IPv4 bandwith is about 935 Mbit/s. But now it gets exciting: The IPv6 bandwith between a Linux machine and the FreeBSD machine is around 450 Mbit/s (each direction). But the IPv4 bandwith between the same machines is 700 (Linux -> FreeBSD) to 920 (FreeBSD -> Linux) Mbit/s. Little table (values in Mbit/s): Configuration v6 v4 ======================================= Linux -> Linux 925 935 # <= This could be v6's 40B header # vs. v4's 20B Linux -> FreeBSD 450 700 FreeBSD -> Linux 455 920 ======================================= The FreeBSD->Linux value shows that the ethernet chip on the FreeBSD machine (it's Intel stuff on both sides, using the em(4) driver on FreeBSD) is able to send at full 1G speed. But why is IPv6 so slow? Regards, Norbert
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