NSX-v Edge trunk port MTU is set to 1500 by default

Products

• VMware NSX Data Center for vSphere

Issue/Introduction

• Newly created trunk interface on the Edge through the NSX User Interface (UI) uses 1500 MTU.
• Interface was created on NSX-v Edge version 6.4.4 or 6.4.5.
• Packet drops may be seen on the interface.
• Existing trunk interfaces are not affected.

Environment

VMware NSX Data Center for vSphere 6.4.x

Cause

In the GUI, when adding a trunk port to an Edge, the default MTU value is set to 1500. In previous versions, the default value was 1600.

Resolution

This issue is resolved in VMware NSX Data Center for vSphere 6.4.6.

 

Workaround:

To manually set the MTU on the trunk interface, access the Advanced tab from the interface edition menu of the Edge.

Note: This is applicable for creation and edition.

1. Navigate to Networking and Security.
2. Select NSX Edges.
3. Double click the affected Edge.
4. Navigate to Manage.
5. Navigate to Settings.
6. Navigate to Interfaces.
7. Select the Trunk Interface.
8. Click Edit.
9. Navigate to Advanced tab.
10. Change the MTU setting from 1500 to 1600 (or intended value).
11. Click Save.
    
    Note: The configuration change is immediate. No restart of the Edge is required.

Additional Information

Impact/Risks:

• Inappropriate MTU may result in packet drop and imply packet retransmissions and latency.
• This issue does not affect existing trunk interfaces on the Edge (if created while on earlier version).