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gnrc_border_router using automatic configuration

This setup uses a single serial interface, ethos (Ethernet Over Serial) and UHCP (micro Host Configuration Protocol) (using DHCPv6 alternatively is also possible). Ethos multiplexes serial data to separate ethernet packets from shell commands. UHCP is in charge of configuring the wireless interface prefix and routes on the BR.

The script start_network.sh enables a ready-to-use BR in only one command.

Uplink

The border router will route packets between a 6Lo network (PAN) and a 'normal' IPv6 network (i.e. the Internet).

This requires the border router to have two interfaces: A downstream interface to run 6LoWPAN on and an IPv6 uplink.

This example comes with support for three uplink types pre-configured:

For native the host-facing netdev_tap device is configured, providing connectivity via a TAP interface to the RIOT instance. On the node-facing side socket_zep is used to simulate a IEEE 802.15.4 network.

To select an uplink, set the UPLINK environment variable. For instance, use UPLINK=slip for a SLIP uplink.

ethos and slip will make use of the existing serial interface that is used for the RIOT shell to provide an upstream interface. Your computer will act as the upstream router, stdio is multiplexed over the same line.

The wifi uplink will connect to an existing WiFi (IEEE 802.11) network. The network must provide a DHCPv6 server that supports prefix delegation (IA_PD) when PREFIX_CONF=dhcpv6 is set (default).

Use WIFI_SSID="SSID" WIFI_PASS="password" in your make command to set your WiFi's credentials. You can alternatively edit the Makefile.

Currently, wifi requires an esp8266 or esp32 for the border router and will default to using esp_now for the downstream interface.

Connection sharing with host

If the host (Linux) computer has an IPv6 uplink that can be shard with the RIOT border router to provide it with an uplink.

This requires the host network to be bridged with the TAP network by connecting it to the TAP bridge:

sudo dist/tools/tapsetup/tapsetup -u eno1

where eno1 is the host's uplink interface.

Then specify REUSE_TAP=1 when building / running the border router application. This works with both native and the ethos uplink.

Requirements

This functionality works only on Linux machines.

If you want to use DHCPv6, you also need a DHCPv6 server configured for prefix delegation from the interface facing the border router. With the KEA DHCPv6 server e.g. you can use the following configuration:

"Dhcp6":
{
  "interfaces-config": {
    "interfaces": [ "tap0" ]
  },
  ...
  "subnet6": [
  {    "interface": "tap0",
       "subnet": "2001:db8::/16",
       "pd-pools": [ { "prefix": "2001:db8::",
                       "prefix-len": 16,
                       "delegated-len": 64 } ] }
  ]
  ...
}

Note that when working with TAP interfaces you might need to restart your DHCPv6 server once after you started the border router application (see below), since Linux might not recognize the interface as connected.

Setup

To compile and flash gnrc_border_router to your board:

make clean all flash

If you want to use DHCPv6 instead of UHCP compile with the environment variable PREFIX_CONF set to dhcpv6

PREFIX_CONF=dhcpv6 make clean all flash

Usage

The start_network.sh script needed for ethos and slip is automatically run if you type

make term

This will execute the needed commands to setup a tap (ethos) or tun (slip) interface and configure the BR. Notice that this will also configure 2001:db8::/64 as a prefix. This prefix should be announced to other motes through the wireless interface.

As said previously, ethos and slipdev allow to send IP packets and shell commands. This is done through the same serial interface. By typing help you will get the list of available shell commands.

At this point you should be able to ping motes using their global address. For instance, if you use the gnrc_networking example on the mote, you can ping it from your machine with:

> ping 2001:db8:0:1234:0:567:8:1

Just replace this address by your mote's address. Using ifconfig on the shell of your mote shows you the addresses of your mote, for instance:

Iface  7   HWaddr: 59:72  Channel: 26  Page: 0  NID: 0x23
            Long HWaddr: 5a:46:10:6e:f2:f5:d9:72
            TX-Power: 0dBm  State: IDLE  max. Retrans.: 3  CSMA Retries: 4
            AUTOACK  CSMA  MTU:1280  HL:64  6LO  RTR  RTR_ADV  IPHC
            Source address length: 8
            Link type: wireless
            inet6 addr: ff02::1/128  scope: local [multicast]
            inet6 addr: fe80::5846:106e:f2f5:d972/64  scope: local
            inet6 addr: ff02::1:fff5:d972/128  scope: local [multicast]
            inet6 addr: 2001:db8::5846:106e:f2f5:d972/64  scope: global
            inet6 addr: ff02::2/128  scope: local [multicast]

The script also sets up a ULA (Unique Local Address) address on your Linux tap0 network interface. You can check your ULA on your PC with ifconfig Linux command. On this example, such address can be pinged from 6lo motes:

> ping fd00:dead:beef::1

Thus far, IPv6 communication with between your PC and your motes is enabled.

Simulated network with native

On native a IEEE 802.15.4 network is simulated by encapsulating 802.15.4 frames inside UDP packets. For this the socket_zep modules is used both on the border router and on the virtual mote.

The UDP packets are sent to a dispatcher which forwards them to all other nodes. By default a simple dispatcher is provided that will forward every packet to every node (perfect broadcast), but it can be replaced by the user with alternative dispatchers to simulate more advanced topologies.

gnrc_border_router with manual config

You can use ethos as a standalone driver, if you want to setup the BR manually.

Setup

To select ethos as the serial driver, be sure that the Makefile has the following:

ifeq (,$(filter native native64,$(BOARD)))
USEMODULE += stdio_ethos
CFLAGS += '-DETHOS_UART=UART_DEV(0)' -DETHOS_BAUDRATE=115200
FEATURES_REQUIRED += periph_uart
endif
# include UHCP client
USEMODULE += gnrc_uhcpc

You'll need IPv6 access to the nodes attached to the BR from your Linux PC. To do this, it is necessary to add a tap interface. As an example, you can do it as follows:

sudo ip tuntap add tap0 mode tap user ${USER}

This will setup your tap interface. Then configure it to route the packets coming from your 6lo network:

sudo ip link set tap0 up
sudo ip a a 2001:db8::1/48 dev tap0
sudo ip r d 2001:db8::/48 dev tap0
sudo ip r a 2001:db8::2 dev tap0
sudo ip r a 2001:db8::/48 via 2001:db8::2 dev tap0

Please note that the prefix 2001:db8:: is used as an example.

Then you can flash the gnrc_border_router example on your board:

make clean all flash

On this RIOT BR two interfaces are present. A wired interface represents the serial link between Linux and your mote. A wireless interface represents the 802.15.4 radio link. In order to route packets between this two interfaces, you can do the following:

> ifconfig 6 add 2001:db8::2/48
> ifconfig 5 add 2001:db8::3/64
> fibroute add :: via <link-local of tap> dev 6

By adding the address to the wireless interface the prefix will be disseminated. This prefix will be automatically added by the motes in the radio range.

Usage

Run ethos by choosing a serial interface according to your board. For instance /dev/ttyUSB* or /dev/ttyACM*.

sudo ./ethos tap0 /dev/ttyACM0

Now, you should be able to ping your nodes. Use the global address starting by your prefix, on our case 2001:db8:::

> ping 2001:db8:0:1234:0:567:8:1

gnrc_networking_border_router with SLIP

Requirements

In order to setup a 6LoWPAN border router on RIOT, you need either a board that offers an IPv6 capable network interface (e.g. the encx24j600 Ethernet chip) or connect it over the serial interface to a Linux host and use the SLIP standard [1]. The example application in this folder assumes as a default to be run on an Atmel SAM R21 Xplained Pro evaluation board using an external UART adapter for the second serial interface. However, it is feasible to run the example on any RIOT supported platform that offers either more than one UART or be equipped with an IPv6 capable network device. In this case only the Makefile.board.dep of this application has to be slightly modified, e.g. by replacing the line

USEMODULE += ethos

with something like

USEMODULE += encx24j600

and specify the target platform as BOARD = myplatform.

Be sure that you have replaced on your Makefile the lines to use SLIP. You should have something like this:

UPLINK ?= slip

Configuration

In order to connect a RIOT 6LoWPAN border router over SLIP you run a small program called tunslip6 (imported from Contiki) [2] on the Linux host. The program can be found in the dist/tools/tunslip folder and has to be compiled before first use (simple calling make should be enough). Now, one can start the program by calling something like:

cd dist/tools/tunslip
make
sudo ./tunslip6 2001:db8::1/64 -t tun0 -s /dev/ttyUSB0

Assuming that /dev/ttyUSB0 is the device descriptor for the (additional) UART interface of your RIOT board.

On the RIOT side you have to configure the SLIP interface by configuring a corresponding IPv6 address, e.g.

ifconfig 6 add 2001:db8::2

and adding the SLIP interface to the neighbor cache (because Linux won't respond to neighbor solicitations on an interface without a link-layer address) by calling

ncache add 6 2001:db8::1

Then, to propagate the prefix you should add an address to the wireless interface:

ifconfig 5 add 2001:db8::3

After this you're basically done and should be able to ping between the border router and the outside world (assuming that the Linux host is properly forwarding your traffic).

Additionally, you can configure IPv6 addresses on the 6LoWPAN interface for communication with other 6LoWPAN nodes. See also the gnrc_networking example for further help.

[1] https://tools.ietf.org/html/rfc1055

[2] https://github.com/contiki-os/contiki/blob/master/tools/tunslip.c