Advance Configuration

This document describes certain advance configurations that you can achieve by setting specific configuration parameters for your Private Cloud Director setup.

MTU & Jumbo Frame Support

The physical network MTU value is configured by default to 1500. This defines the MTU value for all networks in your environment - flat, VLAN, and overlay. Behind the scenes, this becomes the MTU set on internal tenant network ports and what is advertised to VMs to auto-configure via DHCP.

You will only need to configure this value if you wish to use custom MTU for use cases such as jumbo frame enablement.

Note that for overlay networks, this should be the value of physical overlay layer. If left at 1500, VMs and internal ports on tunnel networks get an MTU of 1450 automatically, to account for the VXLAN header added by br-tun before egress.

Configure MTU

Note that changing the default MTU configuration is not exposed to the end user today and must be enabled via your Private Cloud Director support liaison. Please contact the Support team to facilitate this request.

After you override the global physical network MTU parameter, the following will also need to be explicitly set on each hypervisor by updating the ml2_conf.ini file and updating the MTU value for each networks defined. Your support contact will guide you through this process.

ml2_conf.ini

physical_network_mtus = provider:9000,provider2:9000

Changing the global MTU value will not update the MTU for existing networks, You will need to manually change it using CLI/API. Contact support for more information re this.