Dialogic 6.2 Manuale Utente

Q.921/Q.931 Timers

November 2009

332

An application can change the default behavior in Instant ISDN 

Software Level 2 and Level 3 parameters by issuing ENABLE_

PROTOCOL.

L4L3mENABLE_PROTOCOL contains an IISDN_L2_CONST 

structure that defines Level 2 parameters and an IISDN_Q931_

TIMERS structure that configure Level 3 timers. The IISDN_Q931_

TIMERS structure is only valid when the Level 3 mode (l3_mode) 

value in the message is IISDNl3modQ931. 

 and 

 list 

the parameters for both structures.

When altering these values, refer to the system specification for the 

switching system to which you are connecting the Brooktrout 

Controller for valid timer and window values. Level 2 timers are 

specified in 1 millisecond “ticks;” Level 3 timers in 100 millisecond 

“ticks.”

Dialogic strongly recommends that you use the default values 

for Level 2 and Level 3 parameters and internal buffers. 

Failure to do so might result in a system irregularity. If you do 

need to change the configurations and buffer sizes, call 

Dialogic Technical Services and Support first and seek 

consultation. Internal buffer sizes for different Brooktrout 

Controller configurations are found in IISDN.h.

IISDN_L2_

LAP_

CONSTS

12

Setting a field to 0 causes the default value to be 

used. Some timers have two possible default values 

depending on whether or not the line is a BRI (set 

by the q931_cnfg.basic_rate flag.

unsigned 

short

t200

Maximum retransmission time. Default value is 

1000 (1 second).

unsigned 

short

t201

Minimum retransmission TEI Identity check. 

Default value is 1000 (1 second).

unsigned 

short

t202

Minimum TEI Identity request. Default value is 

2000 (2 seconds).

unsigned 

short

t203

Maximum link inactivity. Default value is 30 

seconds. For NET-5 signaling, this timer should be 

set to 10 seconds. BRI default is 10000 (10 

seconds).