for BSNL internal circulation only
E4E4--E5 (E&WS) E5 (E&WS)
Synchronization Synchronization of of
Telecom NetworkTelecom Network
for BSNL internal circulation only
AGENDA
Network Synchronization
Synchronization Planning
BSNL Synchronization Plan
for BSNL internal circulation only
SYNCRONIZATION
Need of Synchronization
Synchronization of the traffic in the networks
is becoming increasingly important due to:
Telecom Traffic in the network is constantly
increasing .
More and more information is being transported
at higher and higher data speeds
Telecommunications’ reliability is based on the
data signals being synchronized.
for BSNL internal circulation only
SYNCRONIZATION
Clocks for Synchronization:
The basic clock in the SDH networks is
called E1, and it must be exactly 2.048 MHz
In a synchronized SDH network, there is a
very stable and accurate atomic (cesium)
clock of 2.048 MHz, functions as a "master
clock" or primary reference clock (PRC).
for BSNL internal circulation only
SYNCHRONIZATION CLOCKS
Accuracy levels of Sync.clocks
PRC
SSU
SEC
Primaryreferenceclock
Synchronizationsupplyunit
SDHequipmentclock
PDH
10-11
10-9 (TNC)10-8 (LNC)
4.6 x 10-6
A c
c u
r a
c y
for BSNL internal circulation only
PRIMARY REFERENCE CLOCKPRIMARY REFERENCE CLOCK
Primary Resource Clock (PRC)Primary Resource Clock (PRC)
The PRC is distributed throughout the network
using the transmission backbone ( DWDM and
SDH network. )
Very stable and accurate atomic (cesium) clock
of 2.048 MHz that functions as a "master clock"
or primary reference clock (PRC).
Accuracy better than 10exp-12
for BSNL internal circulation only
SLAVE CLOCKS
SSUs (Synchronization Supply Unit):
The clock is regenerated in the network’s nodes in
“slave clocks” called as synchronization supply units .
The SSUs are clock of the accuracy better than
10exp-11.
SSUs can also temporarily (up to hold over time) be
used as PRCs, if the input connection from the master
clock is interrupted
for BSNL internal circulation only
SLAVE CLOCKS
SECs (SDH Equip. Clock)
The SECs are the clocks in the network elements.
The SSUs regenerate and distribute the clock thus
received from PRC through a chain of SECs (SDH
Equipment Clocks).
for BSNL internal circulation only
REGENERATION OF PRC CLOCK
PRC: Primary Resource Clock
SEC: SDH Equipment Clock
for BSNL internal circulation only
SYNCHRONIZATION PLANNING
SSU
K=1
PRS
SSU
SSU
Rule 1K < 10 SSUsN < 60 SECs
SEC (NE with SONET/SDH Equipment Clock)
Rule 2N < 20 SECs
K=2
K=3
SSUCo-located PRS & TSG
SSUK=1
1
201 20
PRS
1
20
SSU K=1
1
20
1
20
201
201
1
20
SSU K=2
for BSNL internal circulation only
Clock quality keeps on getting deteriorated as
and when it crosses different nodes.
While extending PRC clock from one node to
other node through transmission network of SDH
and DWDM few planning guidelines are required
to be kept in mind.
SYNCHRONIZATION PLANNING
for BSNL internal circulation only
SYNC. PLANNING
Following is the salient planning rules :
From one PRC maximum 10 numbers of SSUs
can be supported
Between two SSUs maximum 20 NE can be
placed.
In total maximum 60 numbers of NEs can be
supported in one PRC chain .
for BSNL internal circulation only
BSNL SYNCHRONIZATION PLAN
It is decided to have 21 numbers of PRCs with two
cesium tubes (mostly at all Level-1 TAX locations) for
geographical diversity and for ensuring the minimum
nodes slippage.
However, in view of the requirement for the orderly
distribution of the PRC clock throughout the transmission
network, the SSUs may be located at the convergent
nodes of the existing DWDM backbone rings.
for BSNL internal circulation only
� DWDM network enables to transport the clock on a
number of SDH rings to the district head quarters, where
SSUs are proposed to be located.
� Most of these nodes are co-located with the Level –I
TAX stations.
� Thus these 21 PRCs are expected to supply clock for all
the Transmission, Switching and Access elements in the
transmission geographic area.
BSNL SYNCHRONIZATION PLAN
for BSNL internal circulation only
The SSU at the PRC Location.
The SSU at the PRC location depends on the
PRC itself for the first master clock input.
In case of failure or deterioration of the PRC, the
SSU fall back on the other three PRC clock
inputs received from the nearest three PRCs
BSNL SYNCHRONIZATION PLAN
for BSNL internal circulation only
The GPS CLOCK FOR SSU.
SSU draws the clock from the GPS, In the event
of complete failure of the PRC inputs or in the
event of the deterioration of clock quality of all the
PRCs below the GPS standard.
GPS Clock shall be in-built in with SSU
BSNL SYNCHRONIZATION PLAN
for BSNL internal circulation only
BSNL SYNC. PLAN
The provision of SSUs:
• It is proposed to place at least one SSU at each of the
SSA Headquarter ( 322 SSUs).
• In the cities, where more than 3 lakh DELs are available,
there will be at least 3 SSUs in the same city for
distributing the clock across the city network
• Similarly in all the cities with more than one Lakh DELs but
less than 3 Lakh DELs, two SSUs are proposed in the
same city for distributing the clock.
for BSNL internal circulation only
QUESTIONS ?QUESTIONS ?
Introspection:
Why Synchronization is needed in Telecom n/w ?
What are the different types of Synchronization clocks ?
Define PRC ?
Give full name: SSU,SEC,GPS .
Give a brief note on BSNL Synchronization Plan.