Due to continued product development this information may change without notice. If you
find any errors in the documentation, please report them to us in writing. Microsemi doesnot
warrant that this document is error-free.
LimitedProductWarranty
Hardware and embedded software – Depending on the product, for a period of one, or two
years from date of shipment by Microsemi, Microsemi warrants that all Products shall be free
from defects in design, material, and workmanship; shall conform to and perform in accordance with Microsemi's published specifications, if any; shall be free and clear of any liens and
encumbrances; and shall have good and valid title. This warranty will survive inspection,
acceptance, and payment by Buyer. Microsemi does not warrant that the operation of such
Products will be uninterrupted or error free. This warranty does not cover failurescaused by
acts of God, electrical or environmental conditions; abuse, negligence, accident, loss or damage in transit; or improper site preparation.
This warranty shall be null and void in the event (i) Buyer or any third party attemptsrepair of
the goods without Microsemi’s advance written authorization, or (ii) defects are the result of
improper or inadequate maintenanceby Buyer or third party; (iii) of damage to said goods by
Buyer or third party-supplied software, interfacing or supplies; (iv) of improper use (including
termination of non-certified third party equipment on Microsemi’s proprietary interfaces and
operation outside of the product's specifications) by Buyer or third party; or (v) the goods are
shipped to any country other than that originallyspecifiedin the Buyer's purchase order.
Goodsnot meeting the foregoing warranty will be repaired or replaced, at Microsemi’s
option, upon return to Microsemi’s factory freight prepaid; provided, however that Buyer has
first obtained a return materials authorization number ("RMA Number") from Microsemi
authorizing such return. The RMA Number shall be placed on the exterior packaging of all
returns. Microsemi will pay shippingcosts to return repaired or replacement goods to Buyer.
Microsemi reservesthe right to disallow a warranty claim following an inspection of returned
product. When a warranty claim is questioned or disallowed, Microsemi will contact Buyer by
telephone or in writing to resolve the problem.
LimitationofLiability
The remedies provided herein are the Buyer’s sole and exclusive remedies. In no event or circumstanceswill Microsemi be liable to Buyer for indirect, special, incidental or consequential
damages, including without limitation, loss of revenues or profits, business interruption costs,
lossof data or software restoration, or damages relating to Buyer’s procurement of substitute products or services. Except for liability for personal injury or property damage arising
from Microsemi’s negligence or willful misconduct, in no event will Microsemi’s total
3
cumulative liability in connection with any order hereunder or Microsemi’s Goods, from all
causes of action of any kind, including tort, contract, negligence, strict liability and breach of
warranty, exceed the total amount paid by Buyer hereunder. SOME JURISDICTIONS DO
NOT ALLOW CERTAIN LIMITATIONS OR EXCLUSIONS OF LIABILITY, SO THE
ABOVE LIMITATIONS OR EXCLUSIONS MAY NOT APPLY TO ALL BUYERS.
ContactInformation
Microsemi
Frequency and Time Division
3870 N. 1st Street
San Jose, CA 95134
Telephone: +1 (408) 428-7907
For Sales, Technical Support, and Return MaterialsAuthorization, please See "Microsemi
Customer Assistance" on page 5
RevisionHistory
Revision DateDescription
BAugust 2007made corrections, moved and consolidated topics.
COctober 2010Added VDC Power and Telecommunications topics.
DAugust 2011Added models 1520R-350i and 1520R-350i-RB.
D1March 2013Added TACACS+ user authentication, and support for extended
character set in Radius andTACACS+ login.
ENot released.
FNovember 2013Added IPv6 content.
F1May 2015Changed description of downloads for software updates.
4
MicrosemiCustomerAssistance
To find the Microsemi representative closest to your location, please visit Microsemi Worldwide Saleshttp://www.microsemi.com/sales-contacts/0online.
To reach a Microsemi Customer Assistance Center, call one of the following numbers:
n Worldwide Main Number: 1-408-428-7907
n US Toll-free Number: 1-888-367-7966
n Europe, Middle East & Africa: 49 700 32886435
USB Ports112
Console RS-232 Port112
Status LEDs113
Keypad/Display113
Rear Panel114
Radio (LF Radio Module)114
Modem114
Power and Alarm Relays114
Network Ports115
Sysplex Out116
10MHz In117
10MHz Out117
1PPS In117
1PPS Out118
IRIG In (Timecode In)118
IRIG Out (Timecode Out)119
IRIG Control Function Bits120
GPS Receiver121
Chassis Grounding Screw122
WARNING: Grounding122
VDC Power Supply122
WARNING: VDC Power123
VAC Power Supply123
CAUTION: VAC Power123
Power Switch123
Physical124
Environmental124
9
Shock and Vibration124
Accuracy & Stability - Timing Performance124
GPS Antenna125
Timing Holdover126
Network Protocols126
NTP127
CE/WEEE/RoHS Conformance127
Safety Standards128
EMC Standards129
VCCI Compliance Information129
Listing of Memory Devices129
Reliability130
Maintainability130
Web Interface131
Software131
Failure Detection and Reporting131
Warnings and Cautions131
WARNING: Grounding131
WARNING: VDC Power132
WARNING: GPS Antenna132
WARNING: GPS Position and Altitude133
WARNING: Removing Power133
CAUTION: VAC Power133
CAUTION: DHCP Not Available134
CAUTION: Stopping the SyncServer134
CAUTION: Lithium Battery134
Tasks135
Installation Guide136
Unpacking136
Rack Mounting137
Grounding the SyncServer137
WARNING: Grounding137
Connecting VAC Power137
CAUTION: VAC Power138
Electrical Installations in Norway and Sweden138
Connecting VDC Power138
WARNING: VDC Power139
Telecommunications (Modem) Interfaces139
Using GPS140
WARNING: GPS Antenna140
Selecting a Site for the Antenna141
Installing the GPS Antenna142
Operating in "Window Mode"143
Verifyingthe GPS Installation145
GPS Cable Configurations/Options145
10
Configuring LAN1148
CAUTION: DHCP Not Available149
Logging in to the Web Interface149
Using the 1st Setup Wizard149
Configuring the Network Ports149
Adding Server Associations150
Using the Other Input References150
Troubleshooting151
Passwords151
Alarms and Notification151
NTP Clients151
Upgrading System Software152
Web Interface154
Using NTP154
Adding Server Associations154
Adding Peer Associations155
Verifying Server and Peer Associations155
Adding Broadcast Associations156
Adding Multicast Associations157
Configuring NTP Clients158
Using the Modem for Dial-up Time Service159
Working with Generic NTP Devices160
Using NTP Authentication160
Using MD5 Keys on a SyncServer161
Using MD5 Keys on a Generic NTP device162
Using Autokey163
Enabling Secure Login164
Recovering a Password164
Halting the SyncServer165
CAUTION: Stopping the SyncServer165
Backing Up/Restoring Configurations165
Creating a Backup File166
Restoring from a Backup File167
Transferring Configurations167
Restoring the Factory Default Configuration167
WARNING: Removing Power169
Removing the Top Cover169
Replacing the Battery169
Changing the Password175
Enabling Password Recovery175
Creating a New User176
Deleting a Current User176
Estimating Worst Case Time Error when GPS is Unavailable176
Setting the Time Manually177
Distributing GPS Time178
Distributing Non-UTC Time180
Configuring SNMP181
Configuring the SyncServer13
Status LEDs15
Halting the SyncServer15
This topic guides the user on how to:
n Configure a SyncServer that stillhas its original factory configuration.
n Read the status LEDs on the front panel.
n Shut the SyncServer down correctly.
For more information about the featuresand tasksdescribed here, consult the following sections in the main User Guide:
n Web Interface (on page 21)
n Keypad/Display Interface (on page 101)
n Specifications (on page 111)
n Tasks (on page 135)
For your convenience, cross referencesin this QuickStart Guide provide the page numbers
of topics in the main User Guide.
Configuring the SyncServer
Recommended Tasks
GPS antennas not rated for 12 VDC power may be damaged if connected to the SyncServer.
1. Mount the standard L1 GPS antenna (supplied) in a locationthat offers good visibilityof
GPS satellites, such as a rooftop or outdoor antenna mast with wide open views of the
skyand horizon. Avoidobstructions and sources of Radio FrequencyInterference.
Observe building codes and regulations. Also see Using GPS (on page 140) and
WARNING: GPS Antenna (on page 132).
a. Note: For the SyncServer 350i, which doesn't have a GPS receiver, connect an
IRIG signal to the IRIG In connector on the rear panel and skip references to GPS and
antennas in the rest of this procedure.
2. On the rear panel:
n
Connect the GPS antenna cable (supplied) to the GPS Ant connector.
n
Connect LAN1 and any of the other network ports to the network.
n Consult Warnings and Cautions (on page 131) for safety informationregarding
grounding and power.
n Connect the power and turn the power switch on.
3. Using the front panel keypad:
n
Configure LAN1 with a staticIP address using the MENU button and 1) LAN1.
n
View the LAN1 IP address by pressing the STATUS button repeatedly until the
LAN1 STATUS screen is shown.
4.
Go to the SyncServer Login page by entering the LAN1 IP addressas the URL in Internet
Explorer.
5. Log in. The user name is "admin". The password is "symmetricom".
6.
Configure the SyncServer using WIZARDS - 1st Setup. Select the following options:
n "Configure Password Recovery" (Ask the IT department for the IP address of the
SMTP server).
n "Send test mail when finished"
n "Set Local Time Zone"
7.
Configure the remaining network ports using NETWORK - Ethernet.
n Assignstatic IP addresses.
n Protect LAN1 and the other ports from unauthorized IP addresses or address
ranges using the Allowed Access feature.
8. Configure the NTP clients on your network with the IP address(es) of the SyncServer's
network ports.
The SyncServer is providing synchronized time to the network when the SYNC LED (front
panel) is orange or green.
Optional Tasks
In the web interface:
n Connect any other Input References to the rear panel and configure them usingthe
pages under the REFERENCES section.
n
Use the NTP – Config page to synchronize the SyncServer with any other NTP servers.
n
Use WIZARDS - SNMP to set up alarm notification by SNMP.
n
Use SERVICES - Email to set up alarm notification by email.
n
When the SyncServer is completelyconfigured, use WIZARDS - Backup to save a backup
file of the configuration to a safe location. Write the location of the backup file on this printed document and store it in a location that is easy to find.
Page 14..........................................................................997-01520-02 Rev. F1
Status LEDs
The four tricolor LEDs provide the following status information:
RedOrangeGreenDark
Sync
Network
NTP
Alarm
SyncServer is
not synchronized
to a
reference.
NTP Stratum 16.
Link failure on the
LAN1.
>7000 NTP packets persecond.
Major Alarm.Minor Alarm.No Current/Enabled Alarms.Power off.
Also see Stratum (on page 202).
SyncServer is synchronized to a remote
NTP server.
NTP Stratum 2-15.
Link failure on the LAN2,
LAN3, or LANGBE.
> 5000 packets per
second.
SyncServer is synchronized to
an Input Reference or the
modem1.
NTP Stratum 1.
All configured ports operational. Power off.
NTP activity within the last
second.
Status LEDs
Power off.
No NTP
activity in
the last
second.
Halting the SyncServer
Microsemi recommends shutting the operating systemdown before removing the power.
Using the keypad/display interface:
1.
Press the MENU button.
2.
Select 3) Sys Control.
3.
Select 2) Shutdown.
4.
Press the ENTER button.
5. When the displayshows "SystemStopped - OK to Turn Power Off Now!" turn the power
off.
Or, using the web interface:
1.
Go to the SERVICES - Startup page.
2.
Select Halt and clickthe APPLY button.
3. Wait approximately30 seconds before removing power.
The SyncServer Network Time Server offers the following protocolsfor synchronizing equipment over a network:
n NTP
n PTP Grand Master (option)
n SNTP
n Time (TCP and UDP versions)
n Daytime (TCP and UDP versions)
n Sysplex Output (dedicated port)
These protocols are capable of synchronizing computers, servers, and networking equipment on an enterprise-scale network to within milliseconds of officialUTC time. This degree
of synchronization is desirable for precise time-stamping of events and data correlation.
Key Features
n Ultra High-Bandwidth NTP Time Server
n Stratum 1 Operation via GPS* Satellites
n Gigabit Ethernet port plus 3 additionalIndependent 10BASE-T/100BASE-TX Ports
n Internal Dial-up Modem* for Time Reference Redundancy
n Independent Time References: GPS, Timecodes, 1PPS, 10MHz
n VersatileTiming Outputs: IRIG A/B/E/G/NASA36/XR3/2137 AM or DCLS, 1PPS,
10MHz, Sysplex
n Stratum 2 Operation via NTP Servers
n RADIUS, NTPv4 Autokey, MD5 Authentication
n TACACS+Authentication
n Secure Web-Based Management
n SSH, SSL, SCP, SNMP, Custom MIB, HTTPS, Telnet, and More
n IPv6 and IPv4 Compatible
n Nanosecond Time Accuracy to UTC
n Alarm Relays
n Rubidium & OCXO Oscillator Upgrades
n Upgrade to Radio Broadcast Time Sync
n IEEE 1588 / PTP Grandmaster Option
n Time Interval Measurement Option
* Note, the S350i SyncServer does not feature a GPS receiver, or modem.
Key Benefits
n Synchronize Hundreds of Thousands of Client, Server & WorkstationClocks
n Very Reliable and Secure Source of Time for Your Network
n Multiple NTP Ports for Easy Network Configuration and Adaptation
n ExtremelyAccurateTime Source for Network Synchronization
n EnhancedNetwork & SecurityFeatures
n User Prioritized Reference Selection between, GPS, Timecode, 1PPS and 10MHz
n Access MultipleTime Sources for Reliable and Secure Time
n Intuitive Web Interface for Easy Control & Maintenance
Page 22..........................................................................997-01520-02 Rev. F1
Login
Login
Use the Login page to:
n Log in to the Sync Server's web interface.
n Recover lost passwords.
n View system status.
The Login page includes the following elements:
n
Username: Enter the username here. (Factorydefault: "admin")
n
Password: Enter the corresponding password here. (Factory default: "symmetricom")
n
Secure: Opens an encrypted web session (HTTPS, port 443). For this feature to be available, the user must enable it by usingthe SERVICES - HTTP page.
n
Recover Password: Prompts the user to answer a password recovery question. If the user
answers correctly, the Sync Server resets the password to a random string and emailsit
to the user's email address. For this feature to be available, the user must enable it using
the ADMIN - Users or WIZARDS - 1st Setup pages.
Use the ADMIN - Web (on page 82) page to configure the status information on the Login page.
Also see Logging in to the Web Interface (on page 149) and Recovering a Password
(on page 164).
PropertiesofUserNames andPasswords
Usernames
Quantity & Length
There is an upper limit of 32 individual users, each username has a maximum of 32 characters in length.
Character set (Charset)
Each username is limited to the following printable ASCII characters:
n Upper case letters {A-Z}
n Lower case letters {a-z}
n Numbers {0-9}
n Period {.}
n Dash {-}
n Underscore {_}
n Plus {+}
Usernamesmay NOT contain any of the following:
n Standard ASCII keyboard characters not described above, i.e. ! @ # $% ^ & * () = {} [] |
n Grave accent {`}
n Tilde {~}
n Whitespace characters (space, tab, linefeed, carriage-return, formfeed, vertical-tab etc.)
n Non-ASCII characters
n Non-printablecharacters
Passwords
Length
The password can have a maximum of 64 characters in length.
Character set (Charset)
Passwords must contain, at minimum, either a mix of upper and lowercase letters, or a mix of
letters and numbers.
Passwords are limited to the followingprintable ASCII characters:
n Upper case letters {A-Z}
n Lower case letters {a-z}
n Numbers {0-9}
n Tilde {~}
n Most standard ASCII keyboard symbols, i.e. ! @ # $% ^ & * () _ - = {} [] | : ; " < > , . ? /
Passwords may NOT be all-lowercase, all-uppercase, all-numeric, or match the username.
They additionallymay NOT containany of the following:
n Single-quote / apostrophe {'}
n Grave accent {`}
n Plus {+}
n Backslash {\}
n Whitespace characters (space, tab, linefeed, carriage-return, formfeed, vertical-tab etc.)
n Non-ASCII characters
n Non-printablecharacters
STATUS - General
Overall System Information
n
Hostname: The network hostname of the SyncServer, which can be configured on the
SYSTEM - General web page.
n
Model: The model number of the SyncServer.
n
Serial Number: The unique serial number of the SyncServer.
n
Local Time: The local time, determined by the time zone setting on the TIMING - Time Zone
web page.
n
Release Version: The system release version.
Page 24..........................................................................997-01520-02 Rev. F1
STATUS - Network
n
Software Version: The software version.
n
Hardware Clock Version: The version of the software on the Hardware Clock.
n
Up Time: The time elapsed since the operating system started.
n
Load Average: A figure of merit for the operating system “load” for the previous 1, 5, and
15 minutes (left to right).
n
Memory Used (Mbyte): The amount of memory occupied by the system.
n
Memory Free (Mbyte): The amount of free memory remaining.
n
Flash: The type of compact flash card installed.
n
CPU Vendor: The CPU vendor/manufacturer.
n
Model: The CPU model.
n
Number: The CPU number.
STATUS - Network
Network Status for each of the SyncServer's network ports:
n
The name of the Port.
n
The following Address information for each network port:
n
mac: The MAC Address.
n
v4: The IPv4 Address, if used.
n
v6 link: The IPv6 Address, if used.
n
The State of the physical network port device (not of the connection). An "Up Arrow"
meansit is "running". A "Down Arrow" means it is "not running".
Management Port DNS Servers: Both user-entered and DHCP-assignedDNS Server
addresses that are available from the LAN1 port.
The SyncServer requires at least one valid DNS server to resolve domain names, which
may be used in NTP associations, and SMTP gateways (email). Without a DNS server, any
function that uses a DNS name instead of an IP address may be affected. These can include
NTP, password recovery, and email notification of alarms.
Current Sync Source: The Input Reference currently used by the Hardware Clock. Consult the
TIMING - HW Clock topic for more information.
Hardware Clock Time: The time according to the Hardware Clock.
Hardware Clock Status: "Locked" means the Hardware Clockis synchronized to one of its ref-
erences, or to the internal oscillator in "Holdover". "Unlocked" means the Hardware Clock
doesn't have an Input Referenceand the Holdover period has expired. Also see TIMING -HW Clock (on page 61) and TIMING - Holdover (on page 63).
Oscillator Type: The type of the oscillator installed in the Hardware Clockfor operation and holdover.
For each of the following Input Status lines, "Locked"means that the reference is valid and
can be selected by the Hardware Clock. "Unlocked" meansthe reference is not valid, and is
therefore not available for use by the Hardware Clock. Also see TIMING - HW Clock (on
page 61) to arrange the priorityof the Input References.
Some of these references are optionsor are only available in specific SyncServer models.
(Consult Product Overview (on page 17) for more information about featuresand models):
n *GPS Input Status (note, the 350i SyncServer does not have a GPS receiver)
n Timecode Input Status
n 1PPS Input Status
n 10MHz Input Status
n LFR Input Status
* The SyncServer S350i does not have a GPS receiver.
Leap Warning: The state of the Leap Indicator (on page 197) as reported by the current input
reference.
STATUS - GPS
GPS Receiver Operation
This page displays the status of the GPS Receiver.
n Receiver Down: The Hardware Clock can't communicate with the receiver.
n Unknown Mode: An undefined mode of the GPS receiver.
n Acquiring Signal: The receiver is attempting to track a GPS signal.
1
The SyncServer S350i does not include a GPS receiver.
Page 26..........................................................................997-01520-02 Rev. F1
STATUS - GPS
n Bad Geometry: The geometry of the tracked satellitesis unsatisfactory for a position solu-
tion.
n Propagate Mode: A position estimation mode used in highly dynamic environments.
n 2d Solution: The receiver is able to perform position fixes for latitude and longitude but
does not have enough satellites for altitude.
n 3d Solution: The receiver is now able to perform position fixes for latitude, longitude and
altitude.
n Position Hold: Positionfixes are no longer attempted, and the surveyed or user-entered
position is used.
n Time Valid: The receiver has valid timinginformation from GPS satellites (including GPS-
UTC Offset and Leap Indicator). If the GPS receiver and antenna are set up correctly, the
receiver status should eventuallyreach and remain in this state.
Mode:
n Survey: The receiver is surveying and averaging its position. When it has finished sur-
veying, the receiver switches to Position Hold mode. Survey mode and PositionHold
mode are appropriate for static applications, such as a typicalserver room environment.
This is the default mode when the SyncServer starts.
n Dynamic: The GPS receiver surveys continuously to determine its position and doesn't
switch to another mode. This mode must be initiated by a user, and is appropriatefor
mobile applications such as ships, land vehicles, and aircraft. The degree of accuracy this
mode offers is fine for NTP time over networks, but is less than optimal for the timing outputs available on some SyncServer models.
n Position Hold: The GPS receiver has completed Survey mode and switched to this
mode, or the user has manuallyentered a positionand "forced"it into this mode. The
accuracy and stability of the SyncServer's timing outputs are optimalwhen the receiver
has its exact position and is in this mode.
Antenna Cable Delay (nS):
The user-configured value (on the REFERENCES - GPS page) to compensate for GPS signal
propagation from the antenna along the length of the cable to the receiver.
Antenna Status:
The GPS receiver supplies power to the GPS antenna through the antenna cable. It also
monitors the current to that circuit to detect open or short circuits.
n Good: The current to the GPS antenna and cable is normal.
n Open:The current is too low. The GPS antenna or cableis probably disconnected or
broken. Some splitters may cause this condition as well.
n Short: The current is too high. The GPS antenna or cable probably has a short circuit.
Position: The latitude and longitude of the GPS antenna in degrees, minutes, and fractional
seconds. Referenced to WGS-84.
Altitude: The altitude of the antenna in meters. Referenced to WGS-84.
Satellites: The list of GPS satellites visible to the receiver:
n Sat Number: The GPS satellite's Satellite Vehicle (SV) number, a unique identification
number
n Signal: The relative strengthof the GPS signal (dBW = decibels relative to 1 Watt).
n Status: "Current" means that the receiver is usingthe GPS signal in its timing solution.
"Tracked" means the receiver is trackingthe signal, but isn't using it in the timingsolution.
WARNING:GPSPositionandAltitude
GPS position and altitude are for timingpurposes only. They are not intendedfor navigation
or other critical applications.
AVERTISSEMENT : La position et l'altitude de GPS sont seulement pour la synchronization. Ellesne sont pas prévues pour la navigation ou d'autres situations critiques
(situations de la vie-ou-mort).
STATUS - NTP
NTPDaemonStatus
This page displays the status of the NTP daemon. Many of the fieldsbelow are based on the
NTP Packet (on page 198). Also see http://www.ntp.org.
system peer: The IP address of the clocksource. The sourceis selected by the NTP daemon that is most likely to provide the best timing information based on: stratum, distance, dispersion and confidence interval. The system peer identified as "SYMM_TE(0)" is the local
SyncServer Hardware Clock. Also see Hardware Clock (on page 196).
system peer mode: The relationship of the SyncServer to a system peer, usually a "client".
Depending the configuration, the mode can be:
n Client: A host operating in this mode sends periodic messages regardlessof the reach-
ability state or stratum of its peer. By operating in this mode the host, usually a LAN workstation, announcesits willingnessto be synchronized by, but not to synchronize the peer.
n Symmetric Active: A host operating in this mode sends periodic messages regardless
of the reachabilitystate or stratum of its peer. By operating in this mode the host
announces its willingness to synchronize and be synchronized by the peer.
n Symmetric Passive: This type of association is ordinarilycreated upon arrivalof a mes-
sage from a peer operating in the symmetricactive mode and persists onlyas long as the
peer is reachable and operating at a stratum level less than or equal to the host; otherwise, the association is dissolved. However, the association will always persist until at
least one message has been sent in reply. By operating in this mode the host announces
its willingness to synchronize and be synchronized by the peer.
A host operatingin client mode (a workstation, for example) occasionally sendsan NTP message to a host operating in server mode (the SyncServer), perhaps right after rebooting and
at periodic intervals thereafter. The server responds by simply interchanging addresses and
ports, filling in the required time information and returningthe message to the client. Servers
need retain no state information between client requests, while clientsare free to manage
the intervalsbetween sending NTP messages to suit local conditions.
In the symmetric modes, the client/server distinction (almost) disappears. Symmetric passive
mode is intendedfor use by time servers operating near the root nodes (lowest stratum) of
the synchronization subnet and with a relativelylarge number of peers on an intermittent
Page 28..........................................................................997-01520-02 Rev. F1
STATUS - NTP
basis. In this mode the identity of the peer need not be known in advance, since the association with its state variables is created only when an NTP message arrives. Furthermore,
the state storage can be reused when the peer becomes unreachable or is operating at a
higher stratum level and thus ineligible as a synchronization source.
Symmetric active mode is intendedfor use by time servers operating near the end nodes
(highest stratum) of the synchronization subnet. Reliable time service can usuallybe maintained with two peers at the next lower stratum level and one peer at the same stratum level,
so the rate of ongoing polls is usually not significant, even when connectivity is lost and error
messages are being returned for every poll.
leap indicator (LI):
The Leap Indicator (LI) is a two-bit binary number in the NTP packet header that provides
the following information:
n Advance warning that a leap second adjustment will be made to the UTC timescale at the
end of the current day. Leap secondsare events mandated by the world time authority
(BIPM) in order to synchronize the UTC time scale with the earth's rotation.
n Whether the NTP daemon is synchronized to a timing reference. The settings on the
NTP - Prefs (on page 50) page affect LI behavior.
LI ValueMeaning
000No warning.
011Leapsecondinsertion: Last minute of the day has 61 seconds.
102Leapseconddeletion: Last minute of the day has 59 seconds.
113Alarm condition (Not synchronized)
When the SyncServer or NTP daemon is started or restarted, the leap indicator is set to "11",
the alarm condition. This alarm condition makes it possible for NTP clients to recognizethat
an NTP server (the SyncServer) is present, but that it has yet to validate its time from its time
sources. Once the SyncServer finds a valid source of time and sets its clock, it sets the leap
indicator to an appropriate value. The NTP Leap Change Alarm on the ADMIN - Alarms
page can be configured to generate an alarm and send notificationseach time the leap indicator changes state.
stratum:
This is an eight-bit integer that indicates the position of an NTP node within an NTP timing
hierarchy. It is calculated by adding 1 to the stratum of the NTP system peer.
For the SyncServer, the stratum valuesare defined as follows:
StratumDefinition
0Hardware Clock when locked.
1Primary server
2-15Secondary server
16-255Unsynchronized, unreachable.
n stratum 1 when the Hardware Clock (stratum0) is synchronized to an input reference, in
holdover mode, or in freerun mode.
n stratum 2 through 15 when it is synchronized to a remote NTP server.
n stratum 16 when it is unsynchronized, indicating that it is searchingfor a valid source of
timing information.
The settingson the NTP - Prefs (on page 50) page affect stratum behavior.
precision: This is a signed integer indicating the precision of the selected peer clock, in
seconds to the nearest power of two. A typicalvalue is -18 for a Hardware Clock where the
uppermost 18 bits of the time stamp fractional component have value, indicating a precision
in the microsecond range.
root distance (also root delay): This is a measure of the total round trip delay to the root of
the synchronization tree. A typical value for a SyncServer operatingat stratum 1 would be 0
since the SyncServer is a root of the synchronization tree For other stratum levels, an appropriate valueis displayed. Depending on clock skew and dispersion, this value could be positive or negative.
root dispersion: This is a signed fixed-point number indicating the maximum error relative
to the primary reference source at the root of the synchronization subnet, in seconds. Only
positive values greater than zero are possible.
reference ID: This is a four-byte field used to identifythe reference clock source. At initialization, while the stratum is 16, this field shows the progression of the NTP clock PLL. The
field will start with a value of INIT (may be displayed as 73.78.73.84, the ASCII decimalvalues). Once a peer has been selected, the clock may be stepped, in which case the reference
ID field will change to STEP (or 83.84.69.80). Once the PLL is locked, the stratum will be
updatedand the reference ID will identify the selected peer. In the case of a SyncServer
operating at stratum 1, the reference ID will displaythe sourcefor the local timing reference
(e.g., GPS1, IRIG, FREE). In the case where the selected peer is another NTP server, the
reference ID will display the IP addressof the server or a hash unique to the association
between the SyncServer and the remote server.
reference time (also reference timestamp): The time when the SyncServer last received
an update from the selected peer. Represented using time stamp format in local time. If the
local clock has never been synchronized, the valueis zero. A time stamp of zero corresponds
to a local time of Thu, Feb 7 2036 6:28:16.000. This value is typically updatedevery16
seconds for a locally attached hardware reference (e.g., GPS, IRIG) and in an interval of 641024 seconds for a readily accessible remote NTP server.
system flags: These flagsdefine the configured behavior NTP daemon running on the SyncServer. The definitionof the variablesis provided.
n kernel: The NTP daemon is enabled for the precision-time kernelsupport for the ntp_adj-
time() system call.
n monitor: The NTP daemon is enabled its monitoring facility.
n ntp: Enables the server to adjust its local clockby means of NTP.
n stats: The NTP daemon is enabled itsstatistics facility.
n auth: The NTP daemonis enabled itsauthentication facility.
1
The SyncServer S350i does not include a GPS receiver.
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