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UCS vNIC vs Global MTU Comparison Powershell Script

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UCS always recommends to keep vNIC MTU same as that of assigned QoS policy priority class value.

Below warning appears when you assign QoS policy to any vNIC.

vNIC_QoSPolicyWarning.png

 

 

 

When the QoS policy is not assigned to vNIC, it takes the best-efforts class.

 

In huge domains, there are cases where one incorrect setting in service profile template leads to multiple profiles with MTU mismatch and MTU mismatch can lead to issues like packet drops, slow drain for the domain.

 

This powershell script will login to UCS, gather all vNIC Name, MAC Address, VNIC template, vNIC level MTU, set QoS policy Name, set QoS policy MTU value and will compare vNIC level MTU with its corresponding Global QoS MTU. Script will provide an output csv with all mentioned fields and MTU comparison status value.

 

I created this script so that it can be run against single /multiple domains having MTU Mismatch and fetch all vNIC MTU data, allowing one to easily find out all service profiles and vNICs with MTU mismatch. In turn, one can remediate all MTU mismatch issues to avoid slow-drain or CRC related issues.

 

Prerequisites on client machine from where script will be executed:

  PowerShell v3 or greater
  Network access to UCSM
  Cisco UCS PowerTool for PowerShell installed in the client machine

 

Attached zip folder contains two files:

UCS-vNICvsGlobalMTUComparision.ps1 --- Powershell script

ScriptDemo-UCSvNICvsGlobalMTUComparision.docx --- Document explaining script execution steps and output fields

 

Version control:

V1.0 - Initial posted version

 

Please let me know if you have any questions, problems or suggestions.

Comments
Cisco Employee

Congrats Richita , your 1st Devnet upload , what is more important is – you found a problem in customer environment and you were keen to fix it via an automated approach.

 

For past several months , we are aware customers have MTU mismatch in their domains/networks , this UCS vNIC vs Global MTU Comparison Powershell Script will go a long way !!

 

In customers Environment , we have huge domains, there are cases where one incorrect setting in service profile template leads to multiple profiles with MTU mismatch and MTU mismatch can lead to issues like packet drops, slow drain for the domain.

Cisco Employee

Thank you for always guiding me in right direction @imrazack 

Cisco Employee

Great invention Richita! 

Cisco Employee

Good Richita, Keep it up

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