Configure MTU for VXLAN tunnelling

Configure MTU for VXLAN tunnelling
Specific MTU configuration is necessary for VXLAN to function as expected: One option is to increase the MTU value of the physical interface and physical switch fabric by at least 50 bytes. For example, increase the MTU value to 1550. This value enables an automatic 50-byte MTU difference between the physical interface (1500) and the VXLAN interface (automatically 1500-50 = 1450). An MTU value of 1450 causes issues when virtual machine taps are configured at an MTU value of 1500. Another option is to decrease the virtual Ethernet devices' MTU. Set the `network_device_mtu` option to 1450 in the `neutron.conf` file, and set all guest virtual machines' MTU to the same value by using a DHCP option. For information about how to use this option, see Configure OVS plug-in.

Specific MTU configuration is necessary for VXLAN to function as expected:

One option is to increase the MTU value of the physical interface and physical switch fabric by at least 50 bytes. For example, increase the MTU value to 1550. This value enables an automatic 50-byte MTU difference between the physical interface (1500) and the VXLAN interface (automatically 1500-50 = 1450). An MTU value of 1450 causes issues when virtual machine taps are configured at an MTU value of 1500.
Another option is to decrease the virtual Ethernet devices' MTU. Set the network_device_mtu option to 1450 in the neutron.conf file, and set all guest virtual machines' MTU to the same value by using a DHCP option. For information about how to use this option, see Configure OVS plug-in.

https://www.openstack.org/assets/presentation-media/the-notorious-mtu.pdf

如果是vxlan overlay, 很有可能是因为这个。
至于帐号密码报错不知道是什么原因。

On 01/04/2017 07:36 PM, 张博 wrote:

大家好：
        我司部署的OpenStack+KVM架构的资源池出现了如下问题：（下面的操作都是在同一个网段下进行的。）
        在不同物理机下的计算节点创建windos虚拟机（2008和2012都试过）A和B。
        （1）A ping B成功，且A telnet B的 3389端口成功。但是A无法与B远程桌面，且远程桌面的时输入账号密码后报错。
        （2）A 能向 B传输几KB的文件，但是几M的文件或者更大则传输失败，且报错。
       但是相同物理机下面创建的windows虚拟机A、B，它们之间既能远程桌面也能传输大文件。
       且不论是在相同的物理机还是在不同的物理机下面创建centos虚拟机A、B，它们之间也能完成远程登录和大文件的传输。

        请问社区各位学者有无遇到过类似的问题，该如何解决呢？十分感谢！
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