With the conceptual foundation established, let us walk through the complete NVUE configuration sequence for enabling adaptive routing on a Spectrum-X leaf-spine fabric.

Step 1: Enable AR globally on the switch.

AR must be enabled globally before per-interface or per-VRF options are available. Apply to every spine and every leaf switch in the fabric:

# Enable Adaptive Routing globally
nv set router adaptive-routing enable on
nv config apply

# Verify global AR state
nv show router adaptive-routing

Expected output:

Adaptive Routing
================
Enable: on
Mode:   per-flowlet
Flowlet Timer: 100us

Step 2: Set AR mode (per-packet for B200 clusters, per-flowlet for CX7 clusters).

# For DGX B200 clusters with BF3 SuperNIC reorder enabled:
nv set router adaptive-routing mode per-packet
nv config apply

# For DGX H100/H200 clusters (CX7 only):
nv set router adaptive-routing mode per-flowlet
nv set router adaptive-routing flowlet-timer 100us
nv config apply

Step 3: Configure AR per-interface (uplink ports toward spines on leaf switches, downlink ports toward spines on spine switches).

# On leaf-01: enable AR on uplink ports to spines
nv set interface swp49 adaptive-routing enable on
nv set interface swp50 adaptive-routing enable on
nv set interface swp51 adaptive-routing enable on
nv set interface swp52 adaptive-routing enable on
nv config apply

Note: On Spectrum-X, AR is enabled on the egress interface, not the ingress. The AR engine is consulted when selecting the egress port from a set of ECMP candidates.

Step 4: Verify per-interface AR state.

nv show interface swp49 adaptive-routing

Expected output (AR active, traffic being distributed):

Interface swp49 Adaptive Routing
================================
Enable:             on
Mode:               per-packet
Current Queue Depth: 12 KB
AR Decisions Today:  4,821,033
Last AR Redirect:    0.2ms ago
Peer:               spine-01 swp12

Step 5: Verify AR is not active (before fix - what a learner sees when AR is misconfigured).

nv show interface swp49 adaptive-routing

Output when AR disabled or misconfigured:

Interface swp49 Adaptive Routing
================================
Enable:             off
Mode:               N/A
AR Decisions Today:  0
Last AR Redirect:    N/A

Step 6: Verify AR with show commands.

nv show router adaptive-routing detail

Adaptive Routing Detail
=======================
Global Enable:        on
Mode:                 per-flowlet
Flowlet Timer:        100us
ECMP Groups with AR:  8
Active ECMP Paths:    32
AR Decisions (total): 128,441,228
AR Redirects (total): 7,332,018
Redirect Rate:        5.71%
Load Std Deviation:   2.8%   (target: <5%)

The Load Std Deviation metric is the key operational indicator: it measures how evenly AR is distributing traffic across ECMP paths. Values below 5% indicate healthy distribution. Values above 10% suggest AR is not functioning or the flowlet timer is misconfigured.

Interaction with PFC lossless queues in NVUE. AR does not require any modification to the QoS NVUE configuration established in Ch25. The PFC priority mapping (TC3 for RoCEv2, TC6 for CNP) is applied per-port and is independent of the forwarding decision made by AR. Confirm no unintended interaction:

nv show qos roce

Output should show the same ROCE profile as configured in Ch25 - AR has not modified it.