A customer is preparing to deploy a VMware Kubernetes solution in an NSX environment. What is the minimum MTU size for the UPLINK profile?

VMware Kubernetes solutions integrated with NSX-T Data Center, such as vSphere with Tanzu, use the Geneve overlay protocol for container networking. This protocol encapsulates the original network packets, adding header information that increases the total packet size. To prevent IP fragmentation and ensure optimal performance, the Maximum Transmission Unit (MTU) of the underlying physical network infrastructure and the corresponding NSX Uplink Profile must be large enough to accommodate this overhead. While the absolute minimum requirement is 1600 bytes, official VMware reference designs and validated designs recommend a minimum MTU of 1700 bytes as a best practice to ensure robust operation and accommodate any potential additional overhead.

B. 1500: This is the standard Ethernet MTU and does not account for the Geneve overlay encapsulation overhead, which would lead to packet fragmentation and severe network performance degradation.
C. 1550: This value is insufficient to reliably accommodate the Geneve overlay header, which can be 50 bytes or more. It falls below the absolute minimum requirement of 1600 bytes.
D. 1650: Although this value is greater than the absolute technical minimum of 1600 bytes, it is less than the officially recommended best practice of 1700 bytes specified in VMware's design guides.

1. VMware NSX-T Data Center Reference Design Guide: "The MTU of the physical network devices must be set to a value of 1700 bytes or higher to accommodate the Geneve encapsulation overhead. This ensures that traffic is not fragmented in the physical network." (Section: NSX-T Data Center Infrastructure Preparation, Page 21).

2. VMware Validated Design 6.2 - Architecture and Design for the Software-Defined Data Center: "Configure the MTU size of the transport VLANs to at least 1700 bytes to support the Geneve overlay network." (Document: VMware Validated Design for Software-Defined Data Center 6.2, Section: NSX-T Data Center Design Decisions, Table 4.1, Design Item N-NFS-007).

3. VMware NSX-T Data Center Installation Guide: "Set the MTU of all switch ports that are connected to NSX-T host transport nodes to 1600 or greater. This is a minimum requirement to support the Geneve overlay." (Section: System Requirements for NSX-T Data Center, Subsection: Physical Server, NIC, and Switch Requirements). This source establishes the absolute minimum, while the design guides provide the recommended best practice tested in the exam.