Ethernet bridge with native_sim board
This document describes how to set up a bridged Ethernet network between a (Linux) host and a Zephyr application running in a native_sim board.
This setup is useful when testing the Ethernet bridging feature that can be enabled with
CONFIG_NET_ETHERNET_BRIDGE Kconfig option. In this setup, the net-tools
configuration creates two host network interfaces zeth0 and zeth1 and connects them
to Zephyr’s native_sim application.
First create the host interfaces. In this example two interfaces are created.
cd $ZEPHYR_BASE/../tools/net-tools
./net-setup.sh -c zeth-multiface.conf -i zeth0 -t 2
The -c tells which configuration file to use, where zeth-multiface.conf is tailored
for generating multiple network interfaces in the host.
The -i option tells what is the first host interface name. The -t tells how
many network interfaces to create.
Example output of the host interfaces:
zeth0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.0.2.2 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 2001:db8::2 prefixlen 128 scopeid 0x0<global>
inet6 fe80::200:5eff:fe00:5300 prefixlen 64 scopeid 0x20<link>
ether 00:00:5e:00:53:00 txqueuelen 1000 (Ethernet)
RX packets 33 bytes 2408 (2.4 KB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 49 bytes 4092 (4.0 KB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
zeth1: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 198.51.100.1 netmask 255.255.255.255 broadcast 0.0.0.0
inet6 fe80::200:5eff:fe00:5301 prefixlen 64 scopeid 0x20<link>
inet6 2001:db8:2::1 prefixlen 128 scopeid 0x0<global>
ether 00:00:5e:00:53:01 txqueuelen 1000 (Ethernet)
RX packets 21 bytes 1340 (1.3 KB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 45 bytes 3916 (3.9 KB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
Then create a sample and enable Ethernet bridging support. In this example we create Echo server (advanced) sample application.
west build -p -b native_sim -d ../build/echo-server \
samples/net/sockets/echo_server -- \
-DCONFIG_NATIVE_UART_AUTOATTACH_DEFAULT_CMD="\"gnome-terminal -- screen %s\"" \
-DCONFIG_NET_ETHERNET_BRIDGE=y \
-DCONFIG_NET_ETHERNET_BRIDGE_SHELL=y \
-DCONFIG_ETH_NATIVE_POSIX_INTERFACE_COUNT=2 \
-DCONFIG_NET_IF_MAX_IPV6_COUNT=2 \
-DCONFIG_NET_IF_MAX_IPV4_COUNT=2
../build/echo-server/zephyr/zephyr.exe -attach_uart
This will create and run Echo server (advanced) with bridging enabled but not yet configured. To configure the bridging, you either need to use the bridge shell or call the bridging API directly from the application. We setup the bridging using the bridge shell like this:
net bridge addif 1 3 2
net iface up 1
In the above example, the bridge interface index is 1, and interfaces 2 and 3 are
Ethernet interfaces which are linked to interfaces zeth0 and zeth1 in the host side.
The network interfaces look like this in Zephyr’s side:
net iface
Hostname: zephyr
Interface bridge0 (0x8090ebc) (Virtual) [1]
==================================
Virtual name : <enabled>
No attached network interface.
Link addr : 3B:DB:31:0F:CC:B6
MTU : 1500
Flags : NO_AUTO_START
Device : BRIDGE_0 (0x8088354)
Promiscuous mode : disabled
IPv6 not enabled for this interface.
IPv4 not enabled for this interface.
Interface eth0 (0x8090fcc) (Ethernet) [2]
===================================
Link addr : 02:00:5E:00:53:D2
MTU : 1500
Flags : AUTO_START,IPv4,IPv6
Device : zeth0 (0x808837c)
Promiscuous mode : disabled
Ethernet capabilities supported:
TXTIME
Promiscuous mode
Ethernet PHY device: <none> (0)
IPv6 unicast addresses (max 3):
fe80::5eff:fe00:53d2 autoconf preferred infinite
2001:db8::1 manual preferred infinite
IPv6 multicast addresses (max 4):
ff02::1
ff02::1:ff00:53d2
ff02::1:ff00:1
IPv6 prefixes (max 2):
<none>
IPv6 hop limit : 64
IPv6 base reachable time : 30000
IPv6 reachable time : 18476
IPv6 retransmit timer : 0
IPv4 unicast addresses (max 1):
192.0.2.1/255.255.255.0 manual preferred infinite
IPv4 multicast addresses (max 2):
224.0.0.1
IPv4 gateway : 0.0.0.0
Interface eth1 (0x80910dc) (Ethernet) [3]
===================================
Link addr : 02:00:5E:00:53:87
MTU : 1500
Flags : AUTO_START,IPv4,IPv6
Device : zeth1 (0x8088368)
Promiscuous mode : disabled
Ethernet capabilities supported:
TXTIME
Promiscuous mode
Ethernet PHY device: <none> (0)
IPv6 unicast addresses (max 3):
fe80::5eff:fe00:5387 autoconf preferred infinite
IPv6 multicast addresses (max 4):
ff02::1
ff02::1:ff00:5387
IPv6 prefixes (max 2):
<none>
IPv6 hop limit : 64
IPv6 base reachable time : 30000
IPv6 reachable time : 25158
IPv6 retransmit timer : 0
IPv4 unicast addresses (max 1):
<none>
IPv4 multicast addresses (max 2):
224.0.0.1
IPv4 gateway : 0.0.0.0
The net bridge command will show the current status of the bridging:
net bridge
Bridge Status Config Interfaces
1 up ok 2 3
The addif command adds Ethernet interfaces 2 and 3 to the bridge interface 1.
After the addif command, the bridging is still disabled because the bridge interface
is not up by default. The net iface up command will turn on bridging.
If you have wireshark running in host side and monitoring zeth0 and zeth1,
you should see the same network traffic in both host interfaces.
Note that interface index numbers are not fixed, the bridge and Ethernet interface index values might be different in your setup.
The bridging can be disabled by taking the bridge interface down, and the Ethernet interfaces
can be removed from the bridge using delif command.
net iface down 1
net bridge delif 1 2 3