On Mon, Jan 24, 2011 at 4:55 AM, Benoit ML <[email protected]> wrote: > Hi, > Thank you for your reply. > In bridge mode performance is good but I don't have done deep testing ... > Well you pointed me the mtu and effectively, it seems that I have got issue > about that. > It seems that the mtu of the gre tunnel is 1524. Can you confirm that ? > Well have you some suggestion for the guest MTU ? and for the KVM tap device > ?
Where does 1524 come from? What is the underlying MTU of your network? GRE has some overhead for the encapsulation header, which will reduce your effective MTU. The header is variable sized based on what options are enabled but by default on a network with a 1500 byte MTU the tunnel MTU should be 1462. The Open vSwitch implementation attempts to handle path MTU discovery both inside and outside the tunnel to provide the optimal MTU to the sender without any additional configuration required. However, the exact behavior depends on the OS of the sender and its configuration. If an incorrect MTU is chosen it can result in severe performance problems. _______________________________________________ discuss mailing list [email protected] http://openvswitch.org/mailman/listinfo/discuss_openvswitch.org
