RNDIS/ECM (网卡)

1. 概述¶

ECM 以太网控制模型(Ethernet Networking Control Model)用于在设备和主机之间传输以太网数据包。
RNDIS 即RemoteNDIS，既是远程网络驱动接口规范，是微软基于ECM定义的USB网络协议。

2. 板端内核配置（device）¶

本节将分别介绍在linux 平台以及uboot 使用rndis的配置方法

linux 平台配置
```
-> Device Drivers
    -> USB Gadget Support
    -> USB Gadget Drivers
        -> Ethernet Gadget (with CDC Ethernet support)
        -> [*]       RNDIS support
```
如果选上[*] RNDIS support，则支持RNDIS虚拟网卡

生成模块：u_ether.ko usb_f_ecm.ko usb_f_ecm_subset.ko usb_f_rndis.ko g_ether.ko（依赖 libcomposite ）

加载顺序：

u_ether.ko

usb_f_ecm.ko

usb_f_ecm_subset.ko

usb_f_rndis.ko

udc-msb250x.ko/dwc3.ko

g_ether.ko
uboot 平台配置

开启配置
1. CONFIG_CMD_USBSTART
```
-> Command line interface
    -> USB commands
    [*] usbstart
```
2. SSTAR_UTMI_POWERON
```
-> Command line interface
    -> USB commands
    [*] Power on UTMI first
```
配置环境变量

setenv usbnet_devaddr 00:30:78:00:00:02

setenv usbnet_hostaddr 00:50:14:00:00:02

setenv ethact usb_ether

setenv ipaddr 10.10.70.3

setenv netmask 255.0.0.0

setenv gatewayip 10.10.70.1

setenv cdc_connect_timeout 20

启动usb device

usbstart

连上设备可以执行ctrl-c，然后执行ping回到命令行

3. 主机端配置（host）¶

3.1. linux 主机¶

x CONFIG_USB_NET_RNDIS_HOST:
x
x This option enables hosting "Remote NDIS" USB networking links，
x as encouraged by Microsoft (instead of CDC Ethernet!) for use in
x various devices that may only support this protocol.  A variant
x of this protocol (with even less public documentation) seems to
x be at the root of Microsoft's "ActiveSync" too.
x 
x Avoid using this protocol unless you have no better options.
x The protocol specification is incomplete, and is controlled by
x (and for) Microsoft; it isn't an "Open" ecosystem or market.  
x 
x Symbol: USB_NET_RNDIS_HOST [=m]
x Type  : tristate
x Prompt: Host for RNDIS and ActiveSync devices
x   Location:
x     -> Device Drivers
x       -> Network device support (NETDEVICES [=y])
x         -> USB Network Adapters (USB_NET_DRIVERS [=m])
x           -> Multi-purpose USB Networking Framework (USB_USBNET [=m])
x   Defined at drivers/net/usb/Kconfig:383
x   Depends on: NETDEVICES [=y] && USB_NET_DRIVERS [=m] && USB_USBNET [=m]
x   Selects: USB_NET_CDCETHER [=m]
x   Selected by: USB_NET_RNDIS_WLAN [=n] && NETDEVICES [=y] && WLAN [=n] && USB [=m] && CFG80211 [=m]

3.2. window 主机¶

在设备管理器选择需要更新RNDIS驱动的设备
右键“更新驱动程序”
选择第二项“浏览我的计算机以查找驱动程序软件”
选择“从计算机的设备驱动程序选取”
选择网络适配器
厂商选择：Microsoft, 型号选择远程NDIS 兼容设备

4. 网卡使用¶

设备端

网卡名usb0（与linux主机端命名方式一致），配置方式：ifconfig usb0 192.168.1.2
主机端

跟正常网卡使用方式一致，需与设备端网卡ip网段保持一致

5. 动态分配ip¶

可以在连接上host的时候自动给host分配ip

配置对象： device

工具需求： udhcpd

创建leases文件：

mkdir /var/lib/misc/ -p

touch /var/lib/misc/udhcpd.leases

创建配置文件：udhcpd.conf

# Sample udhcpd configuration file (/etc/udhcpd.conf)

# The start and end of the IP lease block

start 192.168.1.20 #default: 192.168.0.20
end 192.168.1.254 #default: 192.168.0.254

# The interface that udhcpd will use

interface usb0 #default: eth0

# The maximim number of leases (includes addressesd reserved
# by OFFER's, DECLINE's, and ARP conficts

#max_leases 254 #default: 254

配置网卡ip：

ifconfig usb0 192.168.1.19

执行命令:

udhcpd -fS /customer/udhcpd.conf &