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 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 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 created by sending an “enable” message to the node.
       If  the  node  is  enabled,  default SSCOP parameters can be retrieved and set in the corresponding SSCOP
       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 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[];
              };

              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 retrieved 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>

Debian                                          October 24, 2003                                     NG_SSCFU(4)