ZEP packet dispatcher ===================== The ZEP dispatcher is a simple daemon that forwards ZEP packets to all connected nodes. ``` usage: zep_dispatch [-t topology] [-s seed] [-g graphviz_out]
``` By default the dispatcher will forward every packet it receives to every other connected node (flat topology). Advanced Topology Mode ---------------------- It is possible to simulate a more complex topology as well as packet loss by specifying a topology file. The file format is: ``` [weight_ab] [weight_ba] ``` This line defines a connection between and . The weight of the edge -> is . An edge weight is a float value between 0 and 1 that represents the probability of a successful packet transmission on that path. A weight of `0` would mean no connection, whereas a weight of `1` would be a perfect connection. Intermediate values are possible, e.g. `0.6` would result in a packet loss probability of 40%. The weights can be omitted. If both weights are omitted, a perfect connection is assumed. If is omitted, a symmetric connection is assumed and is used for both directions. refer to the file `example.topo` for an example. There can only be as many nodes connected to the dispatcher as have been named in the topology file. Any additional nodes that try to connect will be ignored. Packet capture -------------- To view traffic in Wireshark you need to create a virtual 802.15.4 device to which the network traffic is sent. This can then be selected as a capture source in Wireshark. To create the virtual device, load the `mac802154_hwsim` module sudo modprobe mac802154_hwsim This will create two wpan devices, `wpan0` and `wpan1`. If you then run the dispatcher with sudo zep_dispatch -w wpan0 ::1 17754 all traffic on the simulated network will be also sent to the virtual `wpan0` interface where it can be captures with Wireshark. Network visualization --------------------- It is possible to generate a graph of the current simulated network by executing the make graph target. This sends a USR1 signal to the `zep_dispatch` process to generate a graph in Graphviz format. ### Foren6 For real-time visualization of the (RPL) network, the [Foren6](https://cetic.github.io/foren6/) tool can be used. Support for ZEP dispatcher is currently only available through [a fork](https://github.com/benpicco/foren6). #### Foren6 setup Start `foren6` with the `make run` target and in the 'Manage Sources' menu, add a ZEP sniffer: ![](https://user-images.githubusercontent.com/1301112/134354399-7010ad73-044d-4ffa-ad99-61a6838af268.png) The 'target' field takes a hostname:port combination, but you can leave it blank. In that case the default `[::1]:17754` will be used. #### Foren6 usage Foren6 will connect to a running ZEP dispatcher. If the dispatcher started after Foren6 or if the dispatcher was restarted, you have to re-connect by stopping the current capture ('Stop' button) and starting it again ('Start' button). You should see a view of the DODAG with all nodes in the network as they send packets. ![](https://user-images.githubusercontent.com/1301112/144511776-3a2d7072-8162-40dc-911f-dfe476d01112.png) #### RIOT setup A proper simulated network will need a border router and some mesh nodes. The `gnrc_border_router` and `gnrc_networking` can serve as a starting point for those. By default the border router example will start the ZEP dispatcher with a flat topology, that is each node is connected to every other node. This makes for a very boring topology where no RPL is needed. To run the ZEP dispatcher with a custom topology, simply run it before the `gnrc_border_router` example. You can use the `make run` target which will default to the `example.topo` topology. This can be changed with the `TOPOLOGY` environment variable. Next, start the border router example with RPL enabled: USEMODULE=gnrc_rpl make -C examples/gnrc_border_router all term Verify that the border router got a prefix on it's downstream interface with `ifconfig`. ``` Iface 7 HWaddr: 36:DE Channel: 26 NID: 0x23 Long HWaddr: BE:92:89:04:D7:B4:B6:DE L2-PDU:102 MTU:1280 HL:64 RTR RTR_ADV 6LO IPHC Source address length: 8 Link type: wireless inet6 addr: fe80::bc92:8904:d7b4:b6de scope: link VAL --> inet6 addr: 2001:db8::bc92:8904:d7b4:b6de scope: global VAL inet6 group: ff02::2 inet6 group: ff02::1 inet6 group: ff02::1:ffb4:b6de inet6 group: ff02::1a Iface 6 HWaddr: 7A:37:FC:7D:1A:AF L2-PDU:1500 MTU:1500 HL:64 RTR Source address length: 6 Link type: wired inet6 addr: fe80::7837:fcff:fe7d:1aaf scope: link VAL inet6 addr: fe80::2 scope: link VAL inet6 group: ff02::2 inet6 group: ff02::1 inet6 group: ff02::1:ff7d:1aaf inet6 group: ff02::1:ff00:2 ``` Now start as many `gnrc_networking` nodes as you have mesh nodes defined in your topology file: USE_ZEP=1 make -C examples/gnrc_networking all term USE_ZEP=1 make -C examples/gnrc_networking all term … The node should be able to join the DODAG as you can verify with the `rpl` command: ``` instance table: [X] parent table: [X] [ ] [ ] instance [0 | Iface: 7 | mop: 2 | ocp: 0 | mhri: 256 | mri 0] dodag [2001:db8::bc92:8904:d7b4:b6de | R: 768 | OP: Router | PIO: on | TR(I=[8,20], k=10, c=119)] parent [addr: fe80::6467:2e89:b035:d51f | rank: 512] ``` This should also be visible in Foren6. Topology generation ------------------- To generate a random topology use the `topogen.sh` script. This will randomly distribute *N* nodes on on a *W* × *H* map. Each node has a radio range *R* ± *V* where *V* is a random variance that can also be set to 0. The further away a node is from a sending node, the higher the packet loss probability. Nodes outside the sending radius have a zero probability of receiving a packet. If you have `gnuplot` installed this will also generate a plot of the resulting node distribution: ![example topology](https://gist.githubusercontent.com/benpicco/6fd6f7c79a30cbbc41c3a65e53ed3682/raw/33afb859b65d949238129096858d14e2319fb5fb/network.topo.svg) A light color means that a node only has a one-way connection to the network, gray means a node is entirely isolated.