ISO(4)

NAME
iso - ISO protocol family

SYNOPSIS
#include <sys/types.h>
#include <netiso/iso.h>

DESCRIPTION
The ISO protocol family is a collection of protocols that uses the ISO address format. The ISO family provides protocol support for the SOCK_SEQPACKET abstraction through the TP protocol (ISO 8073), for the SOCK_DGRAM abstraction through the connectionless transport protocol (ISO 8602), and for the SOCK_RAW abstraction by providing direct access (for debugging) to the CLNP (ISO 8473) network layer protocol.

ADDRESSING
ISO addresses are based upon ISO 8348/AD2,

Sockets bound to the OSI protocol family use the following address structure:

    struct iso_addr {
         u_char    isoa_len;  /* length, not including this byte */
         char      isoa_genaddr[20];  /* general opaque address */
    };
    struct sockaddr_iso {
         u_char    siso_len;      /* size of this sockaddr */
         u_char    siso_family;   /* addressing domain, AF_ISO */
         u_char    siso_plen;     /* presentation selector length */
         u_char    siso_slen;     /* session selector length */
         u_char    siso_tlen;     /* transport selector length */
         struct    iso_addr siso_addr; /* network address */
         u_char    siso_pad[6];    /* space for gosip v2 SELs */
    };
    #define siso_nlen siso_addr.isoa_len
    #define siso_data siso_addr.isoa_genaddr

The fields of this structure are:

siso_len:
    Length of the entire address structure, in bytes, which may grow to be longer than the 32 bytes shown above.

siso_family:
    Identifies the domain: AF_ISO.

siso_tlen:
    Length of the transport selector.

siso_slen:
    Length of the session selector. This is not currently supported by the kernel and is provided as a convenience for user level programs.

siso_plen:
    Length of the presentation selector. This is not currently supported by the kernel and is provided as a convenience for user level programs.

siso_addr:
    The network part of the address, described below.

TRANSPORT ADDRESSING

An ISO transport address is similar to an Internet address in that it contains a network-address portion and a portion that the transport layer uses to multiplex its services among clients. In the Internet domain, this portion of the address is called a port. In the ISO domain, this is called a transport selector (also known at one time as a transport suffix). While ports are always 16 bits, transport selectors may be of (almost) arbitrary size.

Since the C language does not provide convenient variable length structures, we have separated the selector lengths from the data themselves. The network address and various selectors are stored contiguously, with the network address first, then the transport selector, and so on. Thus, if you had a network address of less then 20 bytes, the transport selector would encroach on space normally reserved for the network address.

NETWORK ADDRESSING.
ISO network addresses are limited to 20 bytes in length. ISO network addresses can take any format.

PROTOCOLS
The ARGO 1.0 implementation of the ISO protocol family comprises the Connectionless-Mode Network Protocol (CLNP), and the Transport Protocol (TP), classes 4 and 0, and X.25. TP is used to support the SOCK_SEQPACKET abstraction. A raw interface to CLNP is available by creating an ISO socket of type SOCK_RAW. This is used for CLNP debugging only.

SEE ALSO
tp(4), clnp(4), cltp(4)