Packet latency when using ENS

Products

• VMware NSX

Issue/Introduction

Resolve the packet latency in ENS mode

Symptoms:
After VMs are vMotioned to destination ESXi transport nodes, the ping latency increases from 1ms to 10 or more between any VMs to the VMs located on the destination ESXi transport nodes and also the Latency increases between any TEPs to the destination ESXi transport nodes.

Environment

VMware NSX-T Data Center

Cause

Only One lcore assigned to ENS:
name            swID maxPorts numActivePorts numPorts mtu   numLcores lcoreIDs
------------------------------------------------------------------------------
DvsPortset-1    0    128      43             43       1600  1         0

Check the lcoreusage and the lcoreusage is 100%
net-stats -A -t EWwqQi -i 2 | egrep "lcoreusage"

   "lcoreusage": 100.00, "pps": 486599 },

Resolution

Assign more lcores to ENS by following:
Accelerated Data Plane Performance Using Enhanced Data Path in NUMA Architecture

After assigning more lcores, if the lcoreusage is not balanced, change vNIC-count mode (default) to CPU-usage mode by following:
Automatically Assign ENS Logical Cores

Additional Information

Impact/Risks:
Latency seen which leads to the network performance being degraded