zmq_udp - Man Page

0MQ UDP multicast and unicast transport

Synopsis

UDP is unreliable protocol transport of data over IP networks. UDP support both unicast and multicast communication.

Description

UDP transport can only be used with the ZMQ_RADIO and ZMQ_DISH socket types.

A 0MQ endpoint is a string consisting of a transport:// followed by an address. The transport specifies the underlying protocol to use. The address specifies the transport-specific address to connect to.

For the UDP transport, the transport is udp. The meaning of the address part is defined below.

Binding a Socket

With udp we can only bind the ZMQ_DISH socket type. When binding a socket using zmq_bind() with the udp transport the endpoint shall be interpreted as an interface followed by a colon and the UDP port number to use.

An interface may be specified by either of the following:

The wild-card *, meaning all available interfaces.
The name of the network interface (i.e. eth0, lo, wlan0 etc...)
The primary address assigned to the interface, in its numeric representation.
Multicast address in its numeric representation the socket should join.

The UDP port number may be specified a numeric value, usually above 1024 on POSIX systems.

Connecting a Socket

With udp we can only connect the ZMQ_RADIO socket type. When connecting a socket to a peer address using zmq_connect() with the udp transport, the endpoint shall be interpreted as a peer address followed by a colon and the UDP port number to use.

A peer address may be specified by either of the following:

The IPv4 or IPv6 address of the peer, in its numeric representation or using its hostname.
Multicast address in its numeric representation.

Examples

Binding a socket.

//  Unicast - UDP port 5555 on all available interfaces
rc = zmq_bind(dish, "udp://*:5555");
assert (rc == 0);
//  Unicast - UDP port 5555 on the local loop-back interface
rc = zmq_bind(dish, "udp://127.0.0.1:5555");
assert (rc == 0);
//  Unicast - UDP port 5555 on interface eth1
rc = zmq_bind(dish, "udp://eth1:5555");
assert (rc == 0);
//  Multicast - UDP port 5555 on a Multicast address
rc = zmq_bind(dish, "udp://239.0.0.1:5555");
assert (rc == 0);
//  Same as above but joining only on interface eth0
rc = zmq_bind(dish, "udp://eth0;239.0.0.1:5555");
assert (rc == 0);
//  Same as above using IPv6 multicast
rc = zmq_bind(dish, "udp://eth0;[ff02::1]:5555");
assert (rc == 0);

Connecting a socket.

//  Connecting using an Unicast IP address
rc = zmq_connect(radio, "udp://192.168.1.1:5555");
assert (rc == 0);
//  Connecting using a Multicast address
rc = zmq_connect(socket, "udp://239.0.0.1:5555);
assert (rc == 0);
//  Connecting using a Multicast address using local interface wlan0
rc = zmq_connect(socket, "udp://wlan0;239.0.0.1:5555);
assert (rc == 0);
//  Connecting to IPv6 multicast
rc = zmq_connect(socket, "udp://[ff02::1]:5555);
assert (rc == 0);