NG_SSCFU(4) BSD Kernel Interfaces Manual NG_SSCFU(4)NAMEng_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 pro‐
vides 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 ALSOnetgraph(4), ng_atm(4), ng_sscop(4), ngctl(8)AUTHORS
Harti Brandt ⟨harti@FreeBSD.org⟩
BSD October 24, 2003 BSD
