cc_SetDLinkState( )

Description | Cautions | Example | Errors | See Also

Name:	int cc_SetDLinkState(bdev, dlinkptr, state_buf)
Inputs:	LINEDEV bdev	device handle
	DLINK *dlinkptr	pointer to data link information block
	int *state_buf	pointer to location of D channel state
Returns:	0 on success < 0 on failure
Includes:	cclib.h
Category:	System tools
Mode:	synchronous
Technology:	BRI/SC; PRI (all protocols)

Description

The cc_SetDLinkState( ) function asks the firmware to set the logical data link state to support specific events in the application.

Upon successful completion of the cc_SetDLinkState( ) function, the request to change the state of the logical link is accepted by the firmware. Subsequently, when the logical data link state changes, the unsolicited event CCEV_D_CHAN_STATUS will be received, indicating that the state has changed.

Parameter	Description
bdev:	Board device handle for PRI, station device handle for BRI.
dlinkptr:	Pointer to the data link information block. See Section 6.4. DLINK for a description of the elements of this data structure.
state_buf:	Pointer to the buffer containing the requested data link state value. Possible data link states are:   DATA_LINK_UP - the firmware attempts to activate the logical link if it is not already activated, and allows the Network side to establish the logical link if requested.   DATA_LINK_DOWN - the firmware attempts to release the logical link if it is currently established, and allows the Network side to establish the logical link if requested.   DATA_LINK_DISABLED - the firmware attempts to release the logical link if it is currently established. The firmware does not allow the Network side to establish the logical link if requested.

Cautions

• There needs to be a sufficient amount of time between bring down the data link layer and bringing it up. This is necessary to allow time for the network side to release its resources and declare the data link down before the network side tries to reestablish the connection.
• Although the cc_SetDLinkState( ) function can be used for PRI, it is somewhat limited in scope. In PRI, after layer 2 is brought down (DATA_LINK_DOWN state), the firmware will try to reestablish the link after the timer expires.

Example

#include <windows.h>   /* For Windows applications only */  
#include <stdio.h>  
#include <errno.h>  
#include "srllib.h"  
#include "dtilib.h"  
#include "cclib.h"  
/* Global variables */  
LINEDEV          ldev;  
main()  
{  
DLINK dlink;  
int state;  
.  
.  
.  
        /* Establish the data link on SAPI 0, CES 1 */  
       dlink.sapi = 0;  
       dlink.ces  = 0;  
       state = DATA_LINK_UP;  
       if(cc_SetDLinkState(ldev, &dlink, &state) < 0) {  
               printf("error");  
       } else {  
              .  
              .  
              .  
       }  
}

Errors

If the function returns < 0 to indicate failure, use the cc_CauseValue( ) function to retrieve the reason code for the failure. The cc_ResultMsg( ) function can be used to interpret the reason code. Error codes are defined in the files ccerr.h, isdnerr.h, and isdncmd.h.

Error codes from the cc_SetDLinkState( ) function include the following:

Error Code	Description
E_BADDEV | ERR_ISDN_LIB	Bad Device Descriptor
E_INVNDIINTERFACE | ERR_ISDN_LIB	Invalid NDI Interface
E_INVNRB | ERR_ISDN_LIB	Invalid NRB

See Also

• cc_GetDLinkState( )

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