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