The DGX H100 and H200 use a straightforward management model: the host CPU runs the OS, DCGM, and all management agents. The BMC is a separate controller for power and hardware monitoring only. The storage and management CX7 NICs are pure network adapters.

The DGX B200 changes this. It replaces the two dual-port CX7 storage NICs with two dual-port BlueField-3 DPUs. These are not just NICs -- each BlueField-3 has its own ARM Cortex-A78 CPU complex (sixteen Cortex-A78 cores running at up to 3.0 GHz), its own DDR5 DRAM, and runs its own independent ARM Linux OS.

This matters for management because the BlueField-3's ARM cores are in the data path, not just monitoring it. On the DGX B200:

• NVMe-oF initiator for storage: runs on the BlueField-3 ARM cores, not the host CPU.
• In-band management NIC: the BlueField-3 acts as the network interface for the host's in-band management traffic (SSH, DCGM exporter, monitoring).
• OVS/networking offload: on B200, the BlueField-3 can run Open vSwitch in hardware, offloading switching decisions from the host CPU.

rshim: the host-to-BlueField-3 communication path

The host CPU communicates with the BlueField-3 via rshim -- a PCIe-based communication channel. rshim presents as a set of character devices on the host:

• /dev/rshim0/boot -- write a BFB (BlueField-3 Bootstream Bundle) image here to reflash the BlueField-3 OS.
• /dev/rshim0/console -- character device giving console access to the BlueField-3's ARM Linux.
• /dev/rshim0/misc -- control channel for BF3 operations.

The rshim channel is how you push firmware and OS updates to the BlueField-3 without physical access to the server:

# On the DGX B200 host: push a new BlueField-3 OS image (BFB file)
# Requires rshim module loaded
lsmod | grep rshim

# Push the BFB image (this reflashes the BF3 and reboots it)
bfb-install --rshim /dev/rshim0 --bfb bf3-bfb-24.1-ubuntu22.04.bfb

# Monitor progress via console
minicom -D /dev/rshim0/console

# After reflash, SSH into the BlueField-3's ARM Linux directly
# BF3 gets its own IP address on the OOB or management network
ssh ubuntu@192.168.100.2  # default BF3 OOB IP (varies per deployment)

BlueField-3 management interface

The BlueField-3 exposes its own management interface (an out-of-band-equivalent path independent of the host OS). In DGX B200 deployments, each BF3 has an oob_net0 interface that connects to the OOB switch alongside the host BMC. From the management workstation, you can reach the BF3's ARM Linux, inspect its NVMe-oF initiator state, check link counters on the storage ports, and upgrade its firmware -- all without the host DGX OS being involved.

# On the BlueField-3 ARM Linux (after SSH to BF3 IP):

# Check NVMe-oF initiator state on the BF3
nvme list-subsys

# BlueField-3 port counters (storage ports)
mlxlink -d /dev/mst/mt41692_pciconf0 -p 1 --show_counters

# Check BF3 firmware version
mlxfwmanager --query

# Upgrade BF3 NIC firmware (separate from OS/BFB upgrade)
mlxfwmanager --update -y /path/to/fw-ConnectX7-rel-28_40_1000.bin

This is the correct home for BlueField-3 engineering content. Ch0 and Ch1 mention that the DGX H100 does NOT have BF3. Ch10 describes the storage architecture difference. Ch18 is where you learn to actually operate the BF3 management layer.