Signalling Connection Control Part (SCCP)

SCCP

Section: The OpenSS7 Project Devices (4)
Updated: Tue, 18 Nov 2008 13:14:02 GMT
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NAME

SCCP - Signalling System No. 7 (SS7) Signalling Connection Control Part (SCCP)

SYNOPSIS

#include <ss7/sccpi.h>
#include <ss7/sccpi_ioctl.h>
#include <sys/npi_sccp.h>
#include <sys/tpi_sccp.h>

#include <sys/xti_sccp.h>

#include <sys/socket.h>
#include <netss7/sccp.h>

int sccp_stream = open(device, flags);
int sccp_xtistr = t_open(device, flags);
int sccp_socket = socket(PF_SS7, socket_type, SS7PROTO_SCCP);

DESCRIPTION

SCCP
is an implementation of the Signalling System No. 7 SS7(4) Signalling Connection Control Part (SCCP) defined in ITU-T Recommendation Q.711 and ANSI T1.112. SCCP provides reliable sequenced or unsequenced delivery of packets over a connectionless or connection oriented transport between two SCCP endpoints. SCCP provides strong assurances that the data arrives in order on a stream, if requested, and maintains sequencing of packets in the face of most network failures. SCCP uses the services of the Message Transfer Part (see mtp(4)) or MTP3 User Adaptation Layer (see m3ua(4)) to transfer packets. SCCP provides a global title translation service that maps global titles to SCCP-SAP.

SCCP is implemented as a STREAMS(4) multiplexing driver. mtp(4) or m3ua(4) streams are linked under the SCCP multiplexing driver using the I_LINK or I_PLINK commands of streamio(7), to provide network services to SCCP. Once linked, the streams must be configured using sccp_ioctl(4).

Device Names

SCCP provides five stream type. To select one of these stream types, device can be one of the following:

/dev/sccp, /dev/sccp-sccpi: This device provides the SCCP protocol services interface using the N-primitives of the Signalling Connection Control Part Interface described in sccpi(7).
/dev/sccp-npi-cl, /dev/sccp-npi-co: This device provides the SCCP protocol service interface using the N-primitives of the Network Provider Interface npi(7) used for the Signalling Connection Control Part as described in sccp_npi(7). The npi(7) service interface is suitable for use with other OpenSS7 SS7 and SIGTRAN modules and drivers, such as the sua-sg(4) multiplexing driver. /dev/sccp-npi-cl provides a connectionless N_CLNS network service provider supporting protocol classes 0 and 1; /dev/sccp-npi-co provides a connection-oriented N_CONS network service provider supporting protocol classes 2 and 3.
/dev/sccp-tpi-cl, /dev/sccp-tpi-co: This device provides the SCCP protocol service interface using the T-primitives of the Transport Provider Interface tpi(7) used for the Signalling Connection Control Part as described in sccp_tpi(7). The tpi(7) interface provided on a stream opening this device is suitable for use with the xnet(3) or xti(3) library and provides the SCCP interface using XTI as described in xti_sccp(3). /dev/sccp-tpi-cl provides a connectionless T_CLTS transport service provider supporting protocol classes 0 and 1; /dev/sccp-tpi-co provides a connection-oriented T_COTS transport service provider supporting protocol classes 2 and 3.

Socket Types

SCCP provides three socket types for use by the sockets (3) library socket (3) call. SCCP provides sockets in the protocol family PF_SS7 using the protocol number SS7PROTO_SCCP. The socket_type argument can be one of the following:

SOCK_DGRAM: Provides a connectionless datagram service without regard to order. Message boundaries are preserved. This is an SCCP protocol class 0 service provider. This socket uses the underlying /dev/sccp-tpi-cl transport service provider.
SOCK_RDM: Provides a connectionless reliable datagram service without regard to order. Message boundaries are preserved. This is an SCCP protocol class 1 service provider. This socket uses the underlying /dev/sccp-tpi-co transport service provider.
SOCK_SEQPACKET: Provides a connection-oriented reliable packet service with regard to order. Message boundaries are preserved. This is an SCCP protocol class 2 or 3 service provider. This socket uses the underlying /dev/sccp-tpi-co transport service provider.

The following entries in /etc/protosw provides the information necessary for socksys(4) to use these devices:

PF_SS7	SOCK_DGRAM	SS7PROTO_SCCP	/dev/sccp-tpi-cl	tpi	clts
PF_SS7	SOCK_RDM	SS7PROTO_SCCP	/dev/sccp-tpi-cl	tpi	clts
PF_SS7	SOCK_SEQPACKET	SS7PROTO_SCCP	/dev/sccp-tpi-co	tpi	cots

For additional information, see socksys(4) and protosw(5).

USAGE

The SCCP STREAMS(4) multiplexing driver provides a number of device names that can be opened by user programs with the open(2s) system call (see above under DeviceNames ). The open(2s) system call returns a file descriptor, fd, that can be used ot make other system calls on the open SCCP Stream. Each SCCP Stream provides a service primitive interface that implements the SCCP protocol The ssytem call, putpmsg(2s), can be called to issue service primitives on the interface; getpmsg(2s), to receive primitives. ioctl(2s) as described in streamio(7) and mtp_ioctl(7) can be used to manage the Stream and the SCCP provider.

IOCTLS

All interfaces support a set of management IO controls using ioctl(2) and streamio(2) I_STR system calls on the sccp_stream, sccp_xtistr or sccp_socket. These management controls are documented in sccp_ioctl(4).

FILES

<ss7/sccpi.h>, <ss7/sccpi_ioctl.h>, <sys/npi.h>, <sys/npi_ss7.h>, <sys/npi_sccp.h>, <sys/tpi.h>, <sys/tpi_ss7.h>, <sys/tpi_sccp.h>, <xti.h>, <xti_sccp.h>.

DEVICES

/dev/sccp, /dev/streams/sccp, /dev/streams/clone/sccp: The SCCP device. These are aliases for the same underlying SCCP device driver.

VERSIONS

The SCCP interface is specific to the OpenSS7 SS7 stack. This is Version 2 of the interface.

REFERENCES

[1]: ITU-T Recommendation Q.711, Functional Description of Signalling Connection Control Part, March 1993, (Geneva), ITU, ITU-T Telecommunication Standardization Sector of ITU. (Previously "CCITT Recommendation") <http://www.itu.int/rec/T-REC-Q.711/>
[2]: ITU-T Recommendation Q.712, Definition and Function of Signalling Connection Control Part Messages, March 1993, (Geneva), ITU, ITU-T Telecommunication Standardization Sector of ITU. (Previously "CCITT Recommendation") <http://www.itu.int/rec/T-REC-Q.712/>
[3]: ITU-T Recommendation Q.713, Signalling Connection Control Part Formats and Codes, March 1993, (Geneva), ITU, ITU-T Telecommunication Standardization Sector of ITU. (Previously "CCITT Recommendation") <http://www.itu.int/rec/T-REC-Q.713/>
[4]: ITU-T Recommendation Q.714, Signalling Connection Control Part Procedures, March 1993, (Geneva), ITU, ITU-T Telecommunication Standardization Sector of ITU. (Previously "CCITT Recommendation") <http://www.itu.int/rec/T-REC-Q.714/>
[5]: ANSI T1.112, Signalling System No. 7 --- Signalling Connection Control Part, 1992, ANSI, American National Standards Institute.