CLNP(4)                   OpenBSD Programmer's Manual                  CLNP(4)

NAME
     clnp - Connectionless-Mode Network Protocol

SYNOPSIS
     #include <sys/socket.h>
     #include <netiso/iso.h>
     #include <netiso/clnp.h>

     int
     socket(AF_ISO, SOCK_RAW, 0);

DESCRIPTION
     CLNP is the connectionless-mode network protocol used by the connection-
     less-mode network service.  This protocol is specified in ISO 8473.  It
     may be accessed through a ``raw socket'' for debugging purposes only.
     CLNP sockets are connectionless, and are normally used with the sendto(2)
     and recvfrom(2) calls, though the connect(2) call may also be used to fix
     the destination for future packets (in which case the read(2) or recv(2)
     and write(2) or send(2) system calls may be used).

     Outgoing packets automatically have a CLNP header prepended to them.  In-
     coming packets received by the user contain the full CLNP header.  The
     following setsockopt options apply to CLNP:

     CLNPOPT_FLAGS  Sets the flags which are passed to clnp when sending a
                    datagram.  Valid flags are:

                          CLNP_NO_SEG    Do not allow segmentation.
                          CLNP_NO_ER     Suppress ER pdus.
                          CLNP_NO_CKSUM  Do not generate the CLNP checksum.

     CLNPOPT_OPTS   Sets CLNP options.  The options must be formatted exactly
                    as specified by ISO 8473, section 7.5.  ``Options Part.''
                    Once an option has been set, it will be sent on all pack-
                    ets until a different option is set.

CONGESTION EXPERIENCE BIT
     Whenever a packet is transmitted, the globally unique quality of service
     option is added to the packet.  The sequencing preferred bit and the low
     transit delay bit are set in this option.

     If a packet is forwarded containing the globally unique quality of ser-
     vice option, and the interface through which the packet will be transmit-
     ted has a queue length greater than congest_threshold, then the conges-
     tion experienced bit is set in the quality of service option.

     The threshold value stored in congest_threshold may be tuned.

     When a packet is received with the globally unique quality of service op-
     tion present, and the congestion experienced bit is set, then the trans-
     port congestion control function is called.

DIAGNOSTICS
     A socket operation may fail with one of the following errors returned:

     [EISCONN]        When trying to establish a connection on a socket which
                      already has one, or when trying to send a datagram with
                      the destination address specified and the socket is al-
                      ready connected;

     [ENOTCONN]       When trying to send a datagram, but no destination ad-
                      dress is specified, and the socket hasn't been connect-

                      ed;

     [ENOBUFS]        When the system runs out of memory for an internal data
                      structure;

     [EADDRNOTAVAIL]  When an attempt is made to create a socket with a net-
                      work address for which no network interface exists;

     [EHOSTUNREACH]   When trying to send a datagram, but no route to the des-
                      tination address exists.

     [EINVAL]         When specifying unsupported options.

SEE ALSO
     recv(2), send(2), iso(4), netintro(4)

BUGS
     Packets are sent with the type code of 0x1d (technically an invalid pack-
     et type) for lack of a better way to identify raw CLNP packets.

     No more than MLEN bytes of options can be specified.

OpenBSD 2.9                      April 2, 1994                               2
