The maximum transmission unit (MTU) value on MX IOMs is 9216 bytes in SmartFabric mode and in full switch mode.
To validate the MTU size for the Dell EMC Networking MX9116n FSE, perform the following steps:
- Log in to the OME-M console.
- Select Devices > I/O Modules.
- Choose an I/O Module and then select Hardware > Port Information and choose appropriate uplink port.
Verify Global MTU value on transport node profile
- From the NSX-T Data Center, validate the MTU size to ensure that the default Global MTU value is set to 1600 bytes:
- From the NSX Manager UI, select Systems > Fabric > Profiles.
- Under the Uplink Profiles section, verify that the MTU column shows 1600 (Global MTU).
Verify MTU under NSX vDS on vCenter
- From the vDS within vCenter, validate the MTU (Bytes) size to ensure that the default value is set to 1500 bytes:
- Log in to the vSphere Client and select Menu > Networking.
- In the left navigation panel, right-click Virtual Distributed Switch.Note: In this deployment, NSX-VDS is shown as the Distributed Switch.
- Hover the cursor over the Settings option and select Edit Settings > Advanced.Note: A configuration error displays if the MTU is less than 1600 Bytes under the vDS in vCenter. The default Global MTU value on NSX-T is 1600 Bytes and must match the MTU value in order for the traffic to pass through. The following figure shows a configuration error.
Increase MTU value
To allow NSX-T traffic encapsulation overhead, increase the MTU value.
To change the MTU size on vDS vCenter, perform the following steps:
- Log in to the vSphere client then select Menu > Networking.
- In the left navigation panel, right-click Virtual Distributed Switch.Note: In this deployment, NSX-VDS is the distributed switch.
- Hover the cursor over Settings, then select Edit Settings.
- From the Edit Settings window, click Advanced and set the following configuration settings:
- MTU (Bytes) - 9000
- Discovery Protocol Type - Link Layer Discovery Protocol
- Operation - Both (optional)
- Click OK.