NAME    [Toc]    [Back]

     ng_sscfu -- netgraph SSCF at the UNI node type

SYNOPSIS    [Toc]    [Back]

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

DESCIPTION    [Toc]    [Back]

     The ng_sscfu netgraph node implements ITU-T recommendation Q.2130.  This
     recommendation specifies the Service Specific Coordination 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 layer of the
     SSCOP and the signals, the UNI expectes 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 created by sending
     an enable message to the node.  If the node is enabled, default SSCOP
     parameters can be retrieved and and set in the corresponding SSCOP
     instance.

     The node is shutdown either by a NGM_SHUTDOWN message or when all hooks
     are disconnected.

HOOKS    [Toc]    [Back]

     Each ng_sscfu node has two hooks with fixed names:

     lower  This hook is the interface to the SSCOP.  The interface 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 message
	    format:

	    struct sscfu_arg {
		    uint32_t sig;
		    u_char   data[];
	    };

	    sig 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 data expected for the
	    signal is specified in parantheses.  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    [Toc]    [Back]

     The ng_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 not be retrieved not set and all
	  message 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 an uint32_t.

     NGM_SSCFU_SETDEBUG
	  Set debugging flags.	The argument must be an uint32_t.

     NGM_SSCFU_GETSTATE
	  Retrieve the current state of the SSCFU instance in an uint32_t.  If
	  the node has not been enabled, 0 is returned.

SEE ALSO    [Toc]    [Back]

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

AUTHORS    [Toc]    [Back]

     Harti Brandt <[email protected]>

FreeBSD 		       October 24, 2003 		       FreeBSD