Test UDP Functionality With OT CLI

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OpenThread offers UDP commands for use with a Thread network to test peer-to-peer communication between UDP sockets. The cli udp provides one sample socket with which all udp commands interact.

The examples that follow demonstrate how you can open and bind sockets, how to connect the socket, and how to send messages using UDP sockets.

UDP commands

For a list of udp commands, type help: 

udp help
bind
close
connect
linksecurity
open
send
Done

open command

Use the udp open command to open the socket to begin UDP communication. You then have the option to bind the socket to a specific IP address and port.

bind command

After you open the socket, you can run a udp bind command to assign an IPv6 address and a port to the open socket. This binds the socket for communication. Assigning the IPv6 address and port is also referred to as naming the socket. If you do not directly bind the socket, connecting the socket (udp connect) or using it in a udp send command binds the socket to an ephemeral port.

connect command

A udp connect command can be used to connect the example socket to a peer socket address. You can then issue a udp send command to send a message to the peer. If the socket is not already bound, issuing the udp connect command also binds the socket.

send command

A udp send command sends a message using the example socket to a destination whose IP address and UDP port can be specified with the command variables. If the IP address and port are not specified in the udp send command, the message gets sent using the example socket to the destination that was specified in the udp connect command. Issuing the udp send command binds the socket to an ephemeral port if the socket has not already been bound.

close command

It is recommended that you use the udp close command to close the socket when the socket is no longer needed.

linksecurity command

The udp linksecurity command can be used to enable or disable data-link layer security for messages.

Send a message between two nodes

  1. On Node 1, open the UDP socket.

    udp open
Done

  2. On Node 1, bind the socket.

    udp bind :: 1234
Done

    The use of :: denotes that the bind should use the unspecified IPv6 address, thereby having the UDP/IPv6 stack assign the binding IPv6 address. For complete options with udp bind, such as binding to a network interface, refer to udp bind.

1 On Node 2, open the UDP socket.

udp open
   Done

  1. On Node 2, send a simple message to Node 1. 

    udp send fdde:ad00:beef:0:bb1:ebd6:ad10:f33 1234 hello
Done

    This command assumes that Node 2 has already discovered the address of Node 1. Additionally, in this example, the administrator of Node 2 has chosen to not bind the socket. This is because the Node 2 administrator wants to send a message to Node 1 without caring which of its IP addresses and ports are used as the Node 2 source. The socket chooses an IP address and port randomly in this scenario.

    For complete options with udp send, refer to udp send.

  2. Node 1 confirms receipt of the message from Node 2:

    5 bytes from fdde:ad00:beef:0:dac3:6792:e2e:90d8 49153 hello

Connect the socket to the peer socket address, then send a message between two nodes

This example is similar to the previous one, but demonstrates some of the flexibility you have in using UDP sockets. With this method, you first connect the socket to the peer socket address, then you do not need to specify the peer IP address and port each time you do a udp send.

  1. On Node 1, open the UDP socket.

    udp open
Done

  2. On Node 1, bind the socket.

    udp bind :: 1234
Done

  3. On Node 2, open the UDP socket.

    udp open
Done

  4. On Node 2, use the udp connect command to open communication to Node 1.

    udp connect fdde:ad00:beef:0:bb1:ebd6:ad10:f33 1234
Done

    For complete options with udp connect, refer to udp connect

  5. On Node 2, use the udp send command to send a message to Node 1, but do not specify ip and port in the udp send command syntax.

    udp send hello
Done

    By not specifying ip and port, the udp send command uses the ip and port that were specified in the udp connect command.