# Azure VM Accelerated Networking Opportunity

> RC-263 fires when a running Azure VM's NIC reports enableAcceleratedNetworking false and either VMNetworkIn or VMNetworkOut peaked at 3 GB or more within a single minute (a sustained 50 MB/s) across a 30-day window. Enabling SR-IOV offload is free, so the recommendation deliberately carries $0 savings.

Source: https://zop.dev/integrations/azure/recommendations/azure-vm-accelerated-networking-opportunity
Updated: 2026-08-19

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## What SR-IOV offload changes for a loaded NIC

Accelerated networking gives the VM single-root I/O virtualization: packets bypass the
host's virtual switch and land directly on the guest NIC. On a machine pushing serious
traffic, the practical effect is lower latency, less jitter, and meaningfully less host
CPU burned on packet processing, capacity that returns to the application. On a quiet NIC
the change is imperceptible, which is exactly why the rule requires proof the NIC is busy
before flagging anything.

## The busy floor, in the units the metric really carries

Azure Monitor's Network In/Out Total series is a sum of bytes with a 1-minute native
grain. ZopNight's aggregator requests it at hourly intervals, so each datapoint's Maximum
is the largest single 1-minute byte total inside that hour, and the series peak is the
busiest minute of the whole 30-day lookback. The decision floor is 3,000,000,000 bytes per
minute, or 50 MB/s sustained for a minute on either direction. An earlier comment mis-read
the series as bytes-per-second and understated the implied rate by 60×; the source now
documents the conversion explicitly.

## Two independent ways it declines to fire

The NIC flag is fail-closed: the discoverer surfaces `enableAcceleratedNetworking` into
metadata as `accelerated_networking`, and the rule abstains unless that value is an
explicit `"false"`. Recommending the toggle on a NIC that already has it would be noise.
Metrics are equally strict: no throughput series for the VM, or a peak below the floor,
and no recommendation exists. Stopped VMs are skipped before any of this runs.

## Verify a NIC's state from the CLI

```bash
az network nic list \
  --query "[?enableAcceleratedNetworking==\`false\`].{nic:name, rg:resourceGroup, vm:virtualMachine.id}" \
  -o table
```

## Turning it on

Confirm the VM size supports accelerated networking first; most current general-purpose
sizes with 2+ vCPUs do. Then update the NIC (`az network nic update
--accelerated-networking true`); some VMs need a brief deallocate/start cycle for the
setting to take. Monthly cost appears on the finding as context only, and savings are $0:
a performance advisory never fabricates a cost fraction. Detection needs Reader plus
Monitoring Reader for the throughput series; ZopNight does not apply this change itself.