network_split/iperf/cp

# network_split / iperf — Coprocessor

Wi-Fi runs on the coprocessor; the host runs its own LWIP / Linux-kernel
TCP/IP stack. The CP forwards 802.3 frames into the host netif (via the
network-split netif backend), so the host owns sockets in the
ephemeral port range (49152–61439) while the CP keeps low ports
(61440–65535) for its own services. This example throws iperf3 at that
split to measure throughput end-to-end.

## Supported Platforms and Transports

### Supported Coprocessors

| Coprocessor | ESP32 | ESP32-C Series | ESP32-S Series |
| :----------: | :---: | :------------: | :------------: |
| Support     | Yes   | Yes            | Yes            |

### Supported Host Devices

| Host Device | ESP32-P4 | ESP32-H2 | Other MCUs | Linux |
| :---------: | :------: | :------: | :--------: | :---: |
| Support     | Yes | Yes | [Yes](https://github.com/espressif/esp-hosted/blob/master/docs/getting-started-mcu.md) | [Yes](https://github.com/espressif/esp-hosted/blob/master/docs/getting-started-linux.md) |

### Supported Connection buses

| Connection bus | SDIO | SPI Full-Duplex | SPI Half-Duplex | UART |
| :------------- | :--: | :-------------: | :-------------: | :--: |
| Linux host     | Yes  | Yes             | No              | No   |
| MCU host       | Yes  | Yes             | Yes             | Yes  |

Enable **Network Split** and select the transport via `idf.py menuconfig`:

```bash
cd examples/network_split/iperf/cp
idf.py set-target esp32c6
idf.py menuconfig
```

```text
Component config
└── ESP-Hosted
     └── Configure coprocessor
          └── CP transport
               ├── Communication bus (co-processor <== bus ==> host)
               │    ├── ( ) SPI Full Duplex
               │    ├── (X) SDIO                    <── default
               │    ├── ( ) SPI Half Duplex         ← MCU host only
               │    └── ( ) UART                    ← MCU host only
               └── SDIO Configuration               ← clock, GPIOs, checksum (defaults OK)
```

The shipped defaults leave Network Split commented out — enable it and
its port / routing rules under **Features**:

```text
Component config
└── ESP-Hosted
     └── Configure coprocessor
          └── Features
               └── [*] Network Split
                    ├── [*] Auto-initialise Network Split at boot
                    ├── [*] Auto-connect WiFi on STA_START (network split)
                    ├── Default network stack for unfiltered packets
                    │    ├── (X) Coprocessor network stack                              <── default
                    │    ├── ( ) Host network stack
                    │    └── ( ) Replicate the packet towards both network stacks (Non recommended)
                    ├── Default DHCP client location
                    │    ├── ( ) Use DHCP at co-processor
                    │    ├── ( ) Use DHCP at Host
                    │    └── (X) Use DHCP at Both sides                                 <── default
                    ├── Slave side (local) LWIP port range (static)
                    │    ├── (61440) Slave TCP start port
                    │    ├── (65535) Slave TCP end port
                    │    ├── (61440) Slave UDP start port
                    │    └── (65535) Slave UDP end port
                    ├── Host side (remote) LWIP port range (static)
                    │    ├── (49152) Host TCP start port
                    │    ├── (61439) Host TCP end port
                    │    ├── (49152) Host UDP start port
                    │    └── (61439) Host UDP end port
                    ├── [*] Configure extra ports dedicated for host network stack
                    └── Host only ports
                         ├── ()        Host reserved TCP source ports
                         ├── (22,8554) Host reserved TCP destination ports
                         ├── ()        Host reserved UDP source ports
                         └── ()        Host reserved UDP destination ports
```

Each bus has its own settings submenu (pins, clock, checksum) — defaults are fine for bring-up.

The CP dependency config is **pre-set in `sdkconfig.defaults`** (do not remove) — note Network Split itself is *not* pre-set and must be enabled in menuconfig:

```text
CONFIG_ESP_HOSTED_CP_FEAT_WIFI=y               # Wi-Fi radio on the CP
CONFIG_BT_ENABLED=n                            # BT off
# CONFIG_ESP_HOSTED_CP_FEAT_NW_SPLIT=y         # NOT pre-set — enable in menuconfig
```

Then flash and monitor:

```bash
idf.py -p <cp_usb_serial_port> flash monitor
```

<!-- generated from ../README.md — edit that file, not this one -->