Virtual Machine MTU Adjustment for Encapsulation Overhead

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Solution Overview

Problem

In virtual network environments, encapsulation overhead often causes packet lengths to exceed the maximum transmission unit (MTU), leading to packet drops or fragmentation, which can significantly disrupt network performance.

Innovation Solution

The host system determines an encapsulation method, calculates an overhead value, and passes an adjusted MTU value to the guest virtual machine, ensuring that data packets do not exceed the MTU by accounting for the encapsulation overhead, thereby preventing packet drops or fragmentation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If encapsulation overhead is added to network packets for routing instructions, then virtual network transparency and routing capability are improved, but packet length exceeds MTU causing packet drops or fragmentation

Engineering Contradiction:

Improvevirtual network transparencyVSAvoidpacket delivery reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The host system performs preliminary calculation of the adjusted MTU value by subtracting encapsulation overhead from the standard MTU before the guest virtual machine sends packets. This advance preparation ensures that guest virtual machines configure their network interfaces with the correct adjusted MTU, preventing packet size issues before they occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The host system acts as an intermediary between the standard MTU specification and the guest virtual machines. It calculates the adjusted MTU value that accounts for encapsulation overhead and communicates this value to guest virtual machines, mediating the conflict between standard packet sizes and virtual network requirements.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If standard MTU is used by guest virtual machines, then network protocol compliance is improved, but encapsulation overhead causes packets to exceed MTU limits

Engineering Contradiction:

Improvenetwork protocol complianceVSAvoidpacket length

Core Design Contradiction:

Ease of operationVSLength of stationary object

Solution Approach 1:

The patent changes the MTU parameter from the standard value to an adjusted value that accounts for encapsulation overhead. The host system calculates this adjusted MTU by subtracting the overhead from the standard MTU and communicates it to guest virtual machines, allowing them to comply with network protocols while accounting for the additional encapsulation layers.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If encapsulation overhead is removed before packets reach destination, then virtual machine awareness is improved, but packet processing complexity increases

Engineering Contradiction:

Improvevirtual machine transparencyVSAvoidpacket processing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The host system extracts and removes the encapsulation overhead from packets before delivering them to the destination guest virtual machine. This extraction process maintains virtual machine transparency by hiding the encapsulation details while the host handles the complexity of adding and removing overhead bytes.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS10164892B2Overhead management for virtual machines

Publication Date: 2018.12.25 RED HAT ISRAEL

AI summary

A method includes loading a guest virtual machine onto a host system, determining, with the host system, an encapsulation method to be used in association with a virtual network associated with the guest virtual machine, determining an overhead value based on the encapsulation method, determining an adjusted maximum transmission unit (MTU) value based on the overhead value, and passing, information related to the adjusted MTU value from the host system to the guest virtual machine.