The following table provides a summary of the MTP3 messages included in this
page:
| Octet 1: |
field |
| bits 4-1 |
Service Indicator (bits DCBA) |
| bits 8-5 |
Sub-service field which contains the network indicator (bits
DC) and two spare bits (bits BA) |
| DCBA |
Service Indicator |
| 0 0 0 0 |
SNMM: Signalling Network Management Messages |
| 0 0 0 1 |
SNTM: Signalling Network Testing and Maintenance Messages |
| 0 0 1 0 |
Spare |
| 0 0 1 1 |
SCCP: Signalling Connection Control Part |
| 0 1 0 0 |
TUP: Telephone User Part |
| 0 1 0 1 |
ISUP: ISDN User Part |
| 0 1 1 0 |
DUPC: Data User Part (call and circuit related messages) |
| 0 1 1 1 |
DUPR: Data User Part (facility registration and cancellation
messages) |
| 1 0 0 0 |
Reserved for MTP Testing User Part |
| DC |
Sub-service field |
| 0 0 |
International Network |
| 0 1 |
Spare (Reserved for national use) |
| 1 0 |
National Network |
| 1 1 |
Reserved for national use |
The standard routing label has a length of 32 bits and is placed at the
beginning of the Signalling Information Field of a MSU:
The following timers have been defined. The ranges are given
below. The values, in brackets, are the minimum values for use when routes with
long propagation delays are used (e.g. routes including satellite sections).
|
Timer |
Value |
Designation |
| T1 |
500 (800) to 1200 ms. |
Delay to avoid message mis-sequencing
on changeover. |
| T2 |
700 (1400) to 2000 ms |
Waiting for changeover acknowledgement |
| T3 |
500 (800) to 1200 ms. |
Time controlled diversion-delay
to avoid mis-sequencing on changeback |
| T4 |
500 (800) to 1200 ms |
Waiting for changeback acknowledgement
(first attempt). |
| T5 |
500 (800) to 1200 ms |
Waiting for changeback acknowledgement
(second attempt). |
| T6 |
500 (800) to 1200 ms |
Delay to avoid message mis-sequencing
on controlled rerouting. |
| T7 |
1 to 2 seconds. |
Waiting for signalling data
link connection acknowledgement. |
| T8 |
800 to 1200 ms. |
Transfer prohibited inhibition
timer (transient solution). |
| T9 |
|
Not used. |
| T10 |
30 to 60 seconds. |
Waiting to repeat signalling
route set test message
The maximum value may be extended at the discretion of the management
function in certain situations, e.g. many signalling points being
unavailable or signalling point of known long term unavailability. |
| T11 |
30 to 90 seconds |
Transfer restricted timer.
(This is one way of implementing the function described in 13.4 and
mainly intended to simplify STPs.) |
| T12 |
800 to 1500 ms. |
Waiting for uninhibit acknowledgement. |
| T13 |
800 to 1500 ms |
Waiting for force uninhibit. |
| T14 |
2 to 3 seconds. |
Waiting for inhibition acknowledgement |
| T15 |
2 to 3 seconds. |
Waiting to start signalling
route set congestion test. |
| T16 |
1.4 to 2 seconds. |
Waiting for route set congestion
status update. |
| T17 |
800 to 1500 ms. |
Delay to avoid oscillation
of initial alignment failure and link restart. |
| T18 |
|
Timer within a signalling
point whose MTP restarts for supervising link and link set activation
as well as the receipt of routing information. The value is implementation
and network dependent.Criteria to choose T18 are given in 9.2 |
| T19 |
67 to 69 seconds |
Supervision timer during MTP
restart to avoid possible ping-pong of TFP, TFR and TRA messages. |
| T20 |
59 to 61 seconds. |
Overall MTP restart timer
at the signalling point whose MTP restarts. |
| T21 |
63 to 65 seconds. |
Overall MTP restart timer
at a signalling point adjacent to one whose MTP restarts. |
| T22 |
3 to 6 minutes (provisional
value) |
Local inhibit test timer. |
| T23 |
3 to 6 minutes (provisional
value). |
Remote inhibit test timer. |
| T24 |
500 ms (provisional value). |
Stabilising timer after removal
of local processor outage, used in LPO latching to RPO (national option) |
