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Reply To: Nokia LAPD measurement

#40095
Jessy
Guest

Hi Guys,

Sorry I’d been away for sometime. In case those didn’t receive the doc, here’s the info.

LAPD measurement
LAPD traffic report (221/DDH)
The logical output file for the ASCII report is the LAPDFROCA and the LAPDFROCB for the binary report.
An example of a LAPD traffic report:
DX 200 MSCLAB 1998-08-01 19:31:34

D-CHANNEL MEASUREMENT REPORT PART 3, LAST PART

TRANSMITTED AND RECEIVED FRAMES AND OCTETS ON D-CHANNEL

MEASUREMENT PERIOD
START : 1998.08.01 18:00:00
END : 1998.08.01 19:30:00

D-CHANNEL : 28 TYPE : PRI

TRANSMITTED RECEIVED
I FRAMES : 162 162
UI FRAMES : 0 0
I FRAME OCTETS : 5022 5022
UI FRAME OCTETS : 0 0
TOTAL OCTET COUNT : 14742 14742

END OF LAST PART

END OF REPORT
The availability report on the signalling links includes the following measurement data on the D-channels that are measured:
Measurement data
·D-CHANNEL
The number of the D-channel.
·TYPE
The type of D-channel ( PRI = primary / SEC = secondary ).
·TRANSMITTED FRAMES / OCTETS
The number of sent frames and octets (0…4294967295). Every I-frame and UI frame is listed separately, as opposed to the total number of octets.
·RECEIVED FRAMES / OCTETS
The number of received frames and octets (0…4294967295). Every I-frame and UI frame is listed separately, as opposed to the total number of octets.

Signalling link load

There are statistical counters that collect information of MTP signalling link availability, performance and utilization. Utilization counters can be used for finding out signalling link loads. The used command are OLU and OLT.
With measurements 3.1 and 3.2 (transmitted SIF+SIO octets), 3.3 (transmitted MSUs), 3.4 (received SIF+SIO octets) and 3.5 (received MSUs) the average link occupancy can be calculated. Measurement periods are 5 and 30 minutes. Samples of 30 minutes periods should be read especially during the busy hour.
Measurement values can be read with the OLU command and signalling link load in Erlangs can be read with the OLT command.
Example 7: Displaying signalling link load
With the OLT command you can display the signalling link load during last measurement period (5 min or 30 min).

The following command displays the signalling link load of signalling links 1 to 5 in active unit during last 5 minutes period.
ZOLT:1&&5,A,P5;

The output could be the following:
DX 200 SP240 1999-05-19 09:59:50
SIGNALLING LINK LOAD
ACTIVE UNIT

METERS OF LAST PERIOD: 09:50:00 – 09:55:00 ( 5 MIN)

RECEIVED TRANSMITTED
LINK ERLANGS ERLANGS
==== ========== ===========
1 0.157 0.152
2 0.000 0.000
3 0.134 0.130
4 0.199 0.199
5 0.105 0.132

COMMAND EXECUTED
Example 8: Calculating the signalling link load
Table 64. “Formula for signalling link calculation (outgoing signalling).”
The sum of counters 3.1 and 3.2 during 30 minutes period is 2.880.000 octets. Counter 3.3 is 144.000 (number of transmitted MSUs). Link capacity is 8192 octets/sec. MTP level 2 overhead should be noted in calculations. Overhead is 6 octets per MSU (F+CK+LI+FSN+BSN).
Level 2 overhead:
6 octets * 144.000 = 864.000 octets
Sent info in link:
2.880.000 + 864.000 = 3.744.000 octets
3.744.000 / 30*60 = 2080 octets/sec.
Link occupancy:
2080 / 8000 = 0.26 Erl.
Table 65. “Formula for signalling link calculation (incoming signalling).”
Recommended link occupancy is 0.2 Erlangs (specified in the ETSI 300 008 specifications). If the occupancy is higher, it is time to consider adding a new link.