ng_sscfu(4)

NAME

ng_sscfu - netgraph SSCF at the UNI node type

SYNOPSIS

#include <netnatm/saal/sscopdef.h>
#include <netnatm/saal/sscfudef.h>
#include <netgraph/atm/ng_sscfu.h>

DESCRIPTION

The sscfu netgraph node type implements ITU-T recommendation

Q.2130.

This recommendation specifies the Service Specific Coordina

tion Function

at the UNI. This is a thin sub-layer between the SSCOP (see

ng_sscop(4))

and the UNI signalling. This node does not really implement

a protocol

but provides a mapping between the signals at the upper lay

er of the

SSCOP and the signals the UNI expects at its lower layer.

It also provides default values for the parameters of the SSCOP.

After creation of the node, the SSCF instance must be creat

ed by sending

an ``enable'' message to the node. If the node is enabled,

default SSCOP

parameters can be retrieved and set in the corresponding SS

COP instance.

The node is shut down either by a NGM_SHUTDOWN message, or

when all hooks

are disconnected.

HOOKS

Each sscfu node has two hooks with fixed names:

lower This hook is the interface to the SSCOP. The in

terface

expected here is exactly that which is exported

by the

ng_sscop(4) node type.

upper This is the interface to the UNI. It uses the

following mes

sage format:

struct sscfu_arg {

uint32_t sig;

u_char data[];

};

The sig field is one of the following signals:

enum saal_sig {

SAAL_ESTABLISH_request, /* U -> SAAL:

(UU) */

SAAL_ESTABLISH_indication, /* SAAL -> U:

(UU) */

SAAL_ESTABLISH_confirm, /* SAAL -> U:

(UU) */

SAAL_RELEASE_request, /* U -> SAAL:

(UU) */

SAAL_RELEASE_confirm, /* SAAL -> U: */

SAAL_RELEASE_indication, /* SAAL -> U:

(UU) */

SAAL_DATA_request, /* U -> SAAL:

(DATA) */

SAAL_DATA_indication, /* SAAL -> U:

(DATA) */

SAAL_UDATA_request, /* U -> SAAL:

(UDATA) */

SAAL_UDATA_indication, /* SAAL -> U:

(UDATA) */

};

The arrows in the comment show the direction of

the signal,

whether it is a signal that comes out of the node

(`->'), or

is sent by the node user to the node (`<-'). The

type of the

data expected for the signal is specified in

parentheses.

This data starts at the data field of the message

structure.

If the lower hook is disconnected and the node is enabled,

the protocol

state is reset.

CONTROL MESSAGES

The sscfu node understands the generic messages plus the

following:

NGM_SSCFU_GETDEFPARAM

This message returns a sscop_param structure, which

contains the

default parameters for the SSCOP at the UNI. This

structure

should be used for a NGM_SSCOP_SETPARAM message to

the SSCOP node

below the SSCF.

NGM_SSCFU_ENABLE

This message creates the actual SSCF instance and

initializes it.

Until this is done, parameters may neither be re

trieved nor set,

and all messages received on any hook are discarded.

NGM_SSCFU_DISABLE

Destroy the SSCF instance. After this, all messages

on any hooks

are discarded.

NGM_SSCFU_GETDEBUG

Retrieve the debugging flags in a uint32_t.

NGM_SSCFU_SETDEBUG

Set debugging flags. The argument must be a

uint32_t.

NGM_SSCFU_GETSTATE

Retrieve the current state of the SSCFU instance in

a uint32_t.

If the node has not been enabled, 0 is returned.

SEE ALSO

netgraph(4), ng_atm(4), ng_sscop(4), ngctl(8)

AUTHORS

Harti Brandt <harti@FreeBSD.org>

BSD October 24, 2003

BSD