Networking Mode
SM
Single Module
CM
SM SM
SM
SM SM
Networking with SM as central
SM SM
Networking with CM as central
Note:
SM can be used independently. But CM can not.
SM carries RSU, but CM does not.
PSM (Peripheral Switching Module) : uses FBI
board as the uplink to the upper module
RSM (Remote Switching Module): uses DTI/ODT
board as the uplink to upper module
FBI DTI/ODT
DTI/ODTFBI
Networking Mode
•Single Module
–SM16, SM8, SM4C, SM4I
•SM as central
–SM16, SM8
•CM as central
–CM256, CM128, CM64, CM32
•PSM
–SM16, SM8
•RSM
–SM16, SM8, SM4C
Inter-module Trunks
–FBI board
•Used between PSM and its host module
•Inter-module trunks: 16 * 8M =16*128=2048DT, 8 of them for
inter-module communication
–ODT board
•Used between RSM and its host module
•Inter-module trunks : 4*8M=4*128=512DT
–E1
•Used between RSM and its host module
•DTI: 4 E1 ports; MDT: 16 E1 ports
•Inter-module trunks : n*2M= n* 30 DT
Agenda
•Networking Mode
•Traffic Calculation
Traffic Calculation (1)
SM
Single Module
Formula: N
L*T
1*x%<N
T*T
2
N
L
: Subscribers
T
1
: Traffic per subscriber
N
T
: Trunks
T
2
: Traffic per trunk
X: percentage of out-going calls
Example:
How many trunks are needed for
an office which has 5000 lines a
nd 80% calls are out-going calls?
In addition, the traffic is 0.1 Erl
per line, 0.8 Erl per trunk?
Answer:
Trunks = 5000*0.1*0.8/0.8=500
E1s= ceiling( 500/30,1) =17
Traffic Calculation (2)
2. For PSM/RSM at the bottom
N
L
*T
1
+N
T
*T
2
< N
B
*T
3
N
L
: Subscribers
T
1
: Traffic per subscriber
N
D
: Trunks
T
2: Traffic per trunk
N
B
: Inter-module trunks
T
3
: Traffic per inter-module trunk =1
3. For PSM/RSM in the middle
N
L
*T
1
+N
T
*T
2
+ ∑SM
i
< N
B
*T
3
N
L
: Subscribers
T
1
: Traffic per subscriber
N
D
: Trunks
T
2
: Traffic per trunk
N
B
: Inter-module trunks
T
3
: Traffic per inter-module trunk =1
SM: the traffic of the lower-level module, i=1,2,3…
CM
SM SM
SM
SM
DTI/ODTFBI
Multiple modules
SM
1. For office
N
L*T
1*X%<N
T*T
2
N
L
: Subscribers
T
1
: Traffic per subscriber
N
T
: Trunks
T
2
: Traffic per trunk
X: percentage of out-going calls
Example
A
C
E
B
D
Question:
There is a project including 5 sites. Accordi
ng to their geographical location, a 3-level n
etworking is proposed as shown in the pictu
re. The capacity of each sites are:
Site A: 5000L
Site B: 3000L plus 20 E1 trunks for inter-o
ffice connection
Site C, D: each having 2000L.
Site E: 800L
Traffic: 0.1Erl per line; 0.8Erl per inter-offic
e trunk; 1 Erl per inter-module trunks
70% calls are out-going calls
Plz, calculate how many inter-office trunks a
re increased in site A and how many inter-m
odule trunks are needed between modules.
Answer:
1. Total inter-office trunks = (5000+3000+2*2000+800)*0.1/0.8*70%/3
0 = 1120/30 =38 E1
So, another 38-20=18 E1 should be increased in site A for inter-office co
nnection.
2. Inter-module trunk between A and C, D and B
Trunks = 2000*0.1/1=200
So, 1 ODT or 7 E1 are used
3. Inter-module trunk between E and B
Trunks = 800*0.1/1=80
So, 1 ODT or 3 E1 are used
3. Inter-module trunk between B and A
Traffic of B = 3000*0.1+20*30*0.8= 780 Erl
Inter-module trunks = (780+200+80)/1 = 1060
So, 1 pairs of FBI are selected
SM4I
•Application
–Only used in single-module networking
•Typical configuration
•Subs. + trunks: 720L+720DT
SM4C
•Application
–Used in single-module networking
–Used as RSM in multi-module networking
•Typical configuration
–In single-module networking
•Single rack: 2400L+600DT
•Two racks: 5280L+600DT
–As RSM in multi-module networking
•Subs.+ trunks:
SM8
•Application
–Used in single-module networking
–Used as PSM/RSM in multi-module networking
•Typical configuration
–In single-module networking
•Subs.+ trunks: 12480L + 2760DT
•Only trunks: 6240DT
–As PSM/RSM in multi-module networking
•Subs.+ trunks:
•Only trunks:
SM16
•Application
–Used in single-module networking
–Used as PSM/RSM in multi-module networking
•Typical configuration
–In single-module networking
•Subs. + trunks: 15360L + 9600DT
•Only trunks: 14400 DT or 7 STM-1
–As PSM/RSM in multi-module networking
•Only trunks:
Model Selection
•The capacity of office: 12800 Lines + 1120DT
•Site B: 3K lines + 600DT(Inter-office) + 280DT (Inter-
module)
•Site C, D: 2K lines + 200DT (Inter-module)
•Site E: 800 lines + 80 DT (Inter-module)
If the future expansion is not considered in this project, the
equipment model for each site is:
Site A: SM8
Site B: SM8
Site C, D: SM4C
Site E: SU960/SU960N