Get guidance on how to set the Maximum Transmission Unit (MTU) value in the different objects or profiles in NSX.
Jumbo Frame Support
The minimum required MTU is 1600 bytes. However, MTU of 1700 bytes is recommended to address the whole possibility of a variety of functions and future proof the environment for an expanding Geneve header. In order to get better performance for applications generating large packets, and for optimal throughput, increase MTU to atleast 9,000 bytes as long as underlay physical infrastructure supports it and is also set to use jumbp frame MTU of 9000 bytes.
VM MTU
In most of the deployments, the guest VM MTU is set to1500 bytes. So no change is required for the VM MTU if the physical fabric has an MTU of 1700 bytes or higher. To improve the throughput, one can increase the MTU up to 8800 (a estimated number to accommodate bridging and future header expansion) only if underlay physical infrastructure is set to to use 9000 bytes. VM MTU should be set 100 bytes or more (200 preferred) lower than the MTU of the physical fabric.
MTU Configuration
- Global Tunnel Endpoint MTU: To configure the MTU value, go to NSX configures the MTU value for all the N-VDS instances used in NSX Transport Nodes. . The default value for MTU is 1700 bytes. When you set this MTU value,
- Global Logical Interface MTU: To configure the MTU value, go to NSX configures the MTU value for all the logical router interfaces. If the Global Logical interface MTU value is not specified, the MTU value is taken from the Tier-0 logical router (T-0 Gateway). However, on a specific port, the logical router uplink MTU value can override the Global Logical interface MTU value. . The default value for MTU is 1500. When you set this MTU value,
- Uplink Profile MTU: To configure the MTU value, go to NSX configures the MTU value for NSX Transport nodes that use N-VDS switch. This MTU field is optional in the uplink profile. If you do not configure it, NSX takes the value set in the global Tunnel Endpoint MTU. . When you set this MTU value,
- (vSphere) VDS MTU: To configure the MTU value, go to the VMware vCenter and modify the VDS directly. When you set this MTU value, NSX configures the MTU value for NSX Transport Nodes that use vSphere VDS. In this case, MTU value set on the attached uplink profile is not used.
Design Guidance
- The underlying infrastructure supports 9000 bytes.
- The underlying infrastructure is set to use jumbo frame MTU of 9000 bytes.