Synchronization
The “Heartbeat” of the Office
Presented by Lisa Carlisle
© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Agenda
• Sync Standards
• Two Aspects of Synchronization
– Components of the Building Integrated Supply (BITS) systems
– Intraoffice Timing Distribution to the receiving Network Elements
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Why are we doing so many BITS clock installations
Engineering Considerations
Installations Considerations
Waivers
Record Keeping
Summary
Questions
© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
AT&T Sync Standards
• AT&T Sync Standards originated from various Telcordia standards
– GR-436-CORE Digital Network Synchronization Plan (documents the
Building Integrated Timing Supply (BITS) concept)
– GR-1244-CORE Clocks for the Synchronized Network: Common
Generic Requirements (covers generic network element interfaces)
– GR-378-CORE Generic Requirements for Timing Signal Generators
(covers TSG’s, aka “BITS Clocks”)
– GR-2830-CORE Primary Reference Source: Generic Criteria (covers
Stratum 1 sources: GPS and Cesium)
• SBC, AT&T Core, BellSouth and AT&T Mobility practices were
consolidated into the current sync sections of TP-76300 and TP76400
• The sync sections of these TPs are subject to continued
refinement as technologies evolve and clarification is needed
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Two Aspects of Synchronization
The Synchronization installations in an office include the BITS ensemble
itself and providing timing references to elements in the office that require
an external timing source
• Components of the BITS system (sometimes called the “clock”)
– Primary Reference Source (PRS) – not necessarily at every office and connected
to the Timing Signal Generator (TSG) via twisted pair (DS1 connection)
• GPS PRS requires the installation of an antenna either on the roof top or “through
the wall” – gets its Stratum 1 traceability from the GPS satellite constellation
• Cesium PRS – stand alone unit installed in the same relay rack as the Timing Signal
Generator
– Timing Signal Generator (TSG) provides the timing outputs used as references
for all the Network Elements that require an external timing source
• Output generation signal type is driven by the card type installed in the TSG or via
software options set up when the output card is placed in the shelf
• Most common output signals are DS1 or Composite Clock – used for traditional TDM
Network Elements
• Packet based timing is beginning to be deployed in the form of Precision Time
Protocol (PTP) or Network Time Protocol (NTP)
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Two Aspects of Synchronization continued
• Intraoffice Distribution of the timing signals to the receiving
Network Elements
– All Network Elements capable of External Timing shall be timed from
the office BITS system
– Most Network Elements require a Primary and Secondary timing lead
that originates from diverse cards in the BITS shelf and routes diversely
to the receiving NE
– Next Generation TSG’s can provide:
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DS1 timing reference
Composite Clock (64 kbps) timing reference
PTP Packet based reference via an electrical or optical SFP on the PTP card
NTP Packet based reference via an electrical or optical SFP on the NTP card
Some TSG’s can provide a 2.048kHz (E1) references
© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Why are We Doing so Many Clock
Installations
• There are approximately 5400 locations (L-S, L-B, L-T wireline
locations) equipped with a BITS clock system and nearly all are or
were equipped with MD’d sync equipment
• A Business Case was approved in mid 2005 and updated as
additional companies were merged into the new AT&T to replace
all the MD’d sync equipment (PRS sources as well as TSG’s)
– Yearly Business Case funding has allowed for the cutover of the MD’d
sync equipment to the currently approved Next Generation sync
equipment in about 150-200 locations per year with the larger locations
being cutover first
– If yearly funding remains at the current rate, the number of office
conversions will increase due to the replacement configurations being
smaller – same money covers more locations
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Why are We Doing so Many Clock
Installations - continued
• The MD’d Sync equipment can include equipment labeled as
Symmetricom, Telecom Solutions, Austron-Datum or HP:
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DCD-ST2 (Telecom Solutions now known as Symmetricom) TSG
DCD-400 (TSG)
DCD-523 (TSG)
TSG3800 (originally labeled DATUM now owned by Symmetricom) TSG
DCD-CIM (Telecom Solutions) TSG
NDSU/SDE (clock distributor)
DCD-LPR (Telecom Solutions/Symmetricom) GPS PRS
PRS-45 (Telecom Solutions/Symmetricom) Cesium PRS
HP 553310A (now Symmetricom) GPS PRS
TS2500 (Symmetricom) GPS PRS
© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Why are We Doing so Many Clock
Installations - continued
• To avoid re-cabling every network element that is receiving a
timing reference from the MD’d clock equipment, the MD’d
equipment wire wrap panel is maintained after the office
conversion
• Maintaining the diversity to the network elements is a must after
the conversion and the next generation clock port capacity is
more dense (20 ports vs. 10 ports) so not only is physical diverse
cable routing necessary but output card diversity in the new clock
needs to be maintained.
• Cutover Y-cables (20 port to two 10 ports) are used to connect
the new clock to the old clock wire wrap panels
• The Cut-over plans (maintaining diversity) are provided in the
Sync Planners ER documents which should be provided in the
Detail Specs and installation requirement and should be followed
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Engineering Considerations
• For the MD’d sync cutover projects the ER document provided by
the Sync Planner is KEY and it needs to be followed during the
engineering phase as well as the installation phase of the project
and should be included in the Detail Spec
• Diversity, Diversity, Diversity
– The BITS clock provides the timing reference to every critical element in
the office and as much diversity that can be obtained should be
obtained
• BDFB powering to the TSG fuse panel should be from diverse BDFB’s if available
or from separate A and B loads if diverse BDFB’s are not available or feasible to
use
• Cabling from the BDFB to the sync bay fuse panel should be diverse
• Output card selection within the TSG should be diverse (even/odd – old DCD
products, separate mated output groups – next gen TSG’s)
• Cabling from the next gen TSG to the old TSG wire wrap panel
• Cabling to network elements receiving timing references
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Engineering Considerations - continued
• Exceptions to Diversity
– Allowable exceptions identified in the TP documents include but not
limited to:
• Use of a single BDFB to provide power, but separate A & B loads should be
used
• Cable runs on the same cable rack when diverse racking is not available
(minimum opposite sides of the cable rack) and the length of commonality
should be minimized
• Use of a common cable hole between floors or rooms to run timing leads
• Use of odd and even cards in old DCD TSG clocks – some regions assigned
output cards in a manner that will not allow for old/even diversity – in this
situation separate cards must be used to provide primary/secondary
timing leads to a network element
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Engineering Considerations - continued
• Cabling from the BITS clock to the network elements is defined in
the TP documents as “Red” jacketed type 1175A single pair
shielded cable. There are two exceptions to this requirement
– Gray jacketed 1175A cable may be used in Legacy AT&T sites (due to
the red color designation being used for power leads)
– Red jacketed 735C coaxial cable is used to connect 2048 MHz analog
sync references to Ericsson 3810 and 3820 RNC’s
• “Red Books” used to display the sync assignments on site are
required at all locations that have on-site records maintained (L-S
and some L-B). If records were maintained locally in some
fashion, a “Red Book” will be required for new clock installations.
The “Red Books” can be filled with computer print outs of the
Tab/DB records and this is the standard for all sites that maintain
on-site sync assignment records. The only sites that do not
require “Red Books” are those sites where on-site records of sync
assignments have never been kept. Examples; Mobility MTSO’s
and some legacy BellSouth sites.
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Engineering Considerations - continued
• Deployment of NTP or PTP in an already existing Symmetricom
TH5500 TSG will require the addition of a horizontal fiber tray
under the front of the shelf to support the front fiber
connection to the NTP or PTP SFP
• Sync output assignments must be updated in the mechanized
record keeping systems (Tab/DB, SyncTrac, GEOLink, etc.) for
new additions as well as the cutover projects
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Installation Considerations
• Diversity, Diversity, Diversity
• Streaker tests
– The streaker tests will identify cabling continuity and polarity
between the output module slots and the wire wrap panels
– Streaker cards have been designed for the Symmetricom TH5500,
SSU-2000 and FEI-Zyfer US5G TSG products and are available from
TAG.
– Streaker tests are required for all new installations of the above
noted TSG products and the results should be included with the job
folder
• Correct labeling on the sync cabling showing to and from
information
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Installation Considerations - continued
• Symmetricom has established some “kits” that include the TSG
shelves, panels, mounting hardware as well as some plug-in
units. These kits are ordered by the MEI and shipped to the
OTV who is responsible for the plug-in units shipped with the
kit. The OTV will be required to provide the plug-ins shipped
with the kits for shelf turn up.
• The OTV needs to inventory received materials against the
material list included in the ER document – some items are not
accounted for or are not what was requested and discrepancies
need to be corrected before the equipment is tested and
turned up for service
• Timing cable shielding should be grounded at one end only –
usually the BITS clock end
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Sync Related Waivers
• Waivers must be submitted for all deviations from the AT&T
Standard Drawings, regardless of who requested the deviation
– If the deviation is at the request of the Sync Planner and the
variance is not covered in the drawing notes that refer to the ER
document, please note the name of the Sync Planner in the text of
the waiver request to help facilitate expedient approval of the
waiver request
• Make sure the most current version of the TP document is
used when determining a waiver request is needed. Read the
TP completely as many exceptions are already identified as
acceptable (i.e. the use of the “Red Books”, odd/even card
assignment in old DCD BITS clocks, etc.)
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Sync Related Waivers - continued
• Be as explicit as possible when submitting a waiver request.
Provide pictures of the situation if possible
• Contact Dave Overdorf, Sync Standards SME, at
do3863@att.com, or 770-232-9183 if there are questions
about the sync sections of the TPs, or an opinion is sought on
the need for a waiver request.
• Don’t submit a waiver request for a violation or deviation that
is found for a situation that is already in service or in place.
Waiver requests are for new installations/work only
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Sync Assignment Recordkeeping
• Depending on the region, the sync assignments are
maintained in different systems
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Legacy SBC uses Tab/DB
Legacy BellSouth uses SyncTrac
Legacy AT&T uses GEOLink
Mobility uses a shared drive that requires permission to update
• OTV responsibilities
– Tab/DB – The OTV is to update the assignments in Tab/DB for all
new assignments and for all cutover projects shall transfer data
from the on-site records or the DCD Tab/DB records. Network
element assignments requiring primary and secondary assignments
must be made in diverse cards in the TSG. All notes identified in
the ER document regarding Tab/DB should be followed.
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Sync Assignment Recordkeeping - continued
• OTV responsibilities - continued
– SyncTrac – a web based system that uses a simple GUI to retrieve and
add data. Records are stored by State and CO. Permissions are
assigned dependent on the level needed, OTV’s are able to make
assignments and add new systems. The OTV reviews the records for
available spare ports and makes assignments in SyncTrac as required
maintaining diversity of card assignments when required.
– GEOLink – Legacy AT&T sync assignments are made by AT&T
personnel currently. The OTV must request the assignment ports via
CSMHotline. The OTV will provide the Name, email address, Phone #,
FIC location, Eq Type and Unit/Shelf # in the request. Once the
assignment is made by AT&T personnel in GEOlink, an email will be
sent to the OTV with the assignment information
– Mobility – The OTV requests any assignment through the MEI who
issues an IWOS request to the NP&E Sync Planner. The assignments
are maintained in the shared drive by the AT&T Sync Planner so the
OTV has no responsibility in maintaining the Mobility sync assignments
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Summary
• AT&T Sync standards are derived from Telcordia standards
documents
• An Office Sync system includes the components of the BITS
system (PRS and TSG) as well as the connection of the timing
references to the network elements in the office
• Sync BITS clock installations will not be slowing for the
foreseeable future due to the extremely high number of MD’d
sync elements currently working in the AT&T network
• Engineering and Installation considerations for sync jobs
– Use the ER documents prepared by the Sync Planner
– Diversity is the KEY
– Avoid some common errors by using the streaker cards, labeling the
cable properly, maintaining diversity identified in the ER document
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Summary - continued
• Know when to submit a waiver request – when in doubt
contact Dave Overdorf for assistance. Provide as much detail
as possible when a waiver request is needed
• Some exceptions are already identified in the TP documents so
a waiver request may not be required
• Sync assignment records vary by region – know your
responsibilities for the installation work being done
• Sync provides the heartbeat to every critical element in an
office, so do your part to keep it healthy
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.
Questions?
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© 2010 AT&T Intellectual Property. All rights reserved. AT&T, the AT&T logo and all other AT&T marks contained herein
are trademarks of AT&T Intellectual Property and/or AT&T affiliated companies. All other marks contained herein are
the property of their respective owners.