SWITCH(4)

NAME
switch - network switch pseudo device

SYNOPSIS
pseudo-device switch

#include <sys/types.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <net/if_bridge.h>

DESCRIPTION
The switch driver provides a network interface pseudo-device. The interface is the forwarding part of a network switch and it works along with a controller, usually switchd(8) or switchctl(8), through the device /dev/switchN. The switch device and the controller communicate using the OpenFlow 1.3 protocol.

A switch interface is created using ifconfig switchN create or by opening the character device /dev/switchN.

/dev/switchN is the OpenFlow channel of the interface switchN. It is used for exchanging OpenFlow messages. The device behaves like a stream, which means that a read(2) may return one or more OpenFlow messages depending on the number of bytes requested. It may also read the message partially (e.g. read(2) the OpenFlow message header and then the complete message). The same applies to write(2) calls, so it may send one or more OpenFlow messages with a single write or use more than one write(2) calls to send a single message.

IOCTLS
A switch interface responds to all of the ioctl(2) calls specific to other interfaces listed in netintro(4).

The following ioctl(2) calls and their structures are commonly used by switch and bridge(4):

•   SIOCBRDGIFS
•   SIOCBRDGADD
•   SIOCBRDGDEL
•   SIOCBRDGGIFFLGS

The following ioctl(2) calls are used only by the switch interface, as defined in <sys/sockio.h>:

SIOCBRDGADDL struct ifbreq *
    Add the interface named in ifbr_ifsname to the switch named in ifbr_name as a local port which connects the local system's network stacks. Only one vether(4) interface can be added as a local port.

SIOCSWGDPID
    Retrieve the datapath_id in the OpenFlow protocol of the switch named in ifbrp_name into the ifbrpu_datapath field.

SIOCSWSDPID struct ifbrparam
    Set the datapath_id in the OpenFlow protocol of the switch named in ifbrp_name to the value in the ifbrpu_datapath field.

SIOCSWGMAXFLOW struct ifbrparam
    Retrieve the maximum number of flows in the OpenFlow protocol of the switch named in ifbrp_name into the ifbrp_maxflow field.

SIOCSWGMAXGROUP struct ifbrparam
    Retrieve the maximum number of groups in the OpenFlow protocol of the switch named in ifbrp_name into the ifbrpu_maxgroup field.

SIOCSWSPORTNO struct ifbreq
    Set the port_no in the OpenFlow protocol of the port named in ifbr_ifsname of the switch named in ifbr_name to the ifbr_portno field.

FILES
/dev/switch*

ERRORS
If open fails, errno(2) may be set to one of:

[ENXIO]
    Could not create the interface.

[EBUSY]
    The device was already opened.

[ENOBUF]
    Out of memory.

SEE ALSO
bridge(4), inet(4), inet6(4), vether(4), hostname.if(5), ifconfig(8), netstart(8), switchctl(8), switchd(8)

STANDARDS
Open Networking Foundation (ONF), March 26, 2015, Version 1.3.5 (Protocol version 0x04), OpenFlow Switch Specification.

HISTORY
The switch driver first appeared in OpenBSD 6.1.

AUTHORS
The switch driver was written by Kazuya Goda <goda@openbsd.org>.