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Junos®OS Time Management Administration Guide for Routing Devices
The information in this document is current as of the date on the title page.
YEAR 2000 NOTICE
Juniper Networks hardware and software products are Year 2000 compliant. Junos OS has no known time-related limitations through the
year 2038. However, the NTP application is known to have some difficulty in the year 2036.
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Supported Platforms
For the features described in this document, the following platforms are supported:
Time Management Administration Guide for Routing Devices
Using the Examples in This Manual
If you want to use the examples in this manual, you can use the load merge or the load
merge relative command. These commands cause the software to merge the incoming
configuration into the current candidate configuration. The example does not become
active until you commit the candidate configuration.
If the example configuration contains the top level of the hierarchy (or multiple
hierarchies), the example is a full example. In this case, use the load merge command.
If the example configuration does not start at the top level of the hierarchy, the example
is a snippet. In this case, use the load merge relative command. These procedures are
described in the following sections.
Merging a Full Example
To merge a full example, follow these steps:
1. From the HTML or PDF version of the manual, copy a configuration example into a
text file, save the file with a name, and copy the file to a directory on your routing
platform.
For example, copy thefollowingconfigurationto a file and name the file ex-script.conf.
Copy the ex-script.conf file to the /var/tmp directory on your routing platform.
system {
scripts {
commit {
file ex-script.xsl;
}
}
}
interfaces {
fxp0 {
disable;
unit 0 {
family inet {
address 10.0.0.1/24;
}
}
}
}
2. Merge the contents of the file into your routing platform configuration by issuing the
Indicates a choice between the mutually
exclusivekeywords or variables on either
side of the symbol. The set of choices is
often enclosed in parentheses for clarity.
same lineas the configuration statement
to which it applies.
Encloses a variable for which you can
substitute one or more values.
Identifies a level in the configuration
hierarchy.
Identifies a leaf statement at a
configuration hierarchy level.
broadcast | multicast
(string1 | string2 | string3)
rsvp { # Required for dynamic MPLS onlyIndicates a comment specified on the
Representsgraphicaluser interface (GUI)
items you click or select.
About the Documentation
ExamplesDescriptionConvention
•
In the Logical Interfaces box, select
All Interfaces.
•
To cancel the configuration, click
Cancel.
> (bold right angle bracket)
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Requesting Technical Support
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or are covered under warranty, and need post-sales technical support, you can access
our tools and resources online or open a case with JTAC.
Separates levels in a hierarchy of menu
selections.
In the configuration editor hierarchy,
select Protocols>Ospf.
•
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review the JTAC User Guide located at
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Opening a Case with JTAC
You can open a case with JTAC on the Web or by telephone.
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Use the Case Management tool in the CSC at http://www.juniper.net/cm/.
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Call 1-888-314-JTAC (1-888-314-5822 toll-free in the USA, Canada, and Mexico).
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Network Time Protocol (NTP) is a widely used protocol used to synchronize the clocks
of routers and other hardware devices on the Internet. Primary NTP servers are
synchronizedto areferenceclock directlytraceableto Coordinated Universal Time(UTC).
Reference clocks include GPS receivers and telephone modem services, NTP accuracy
expectations depend on the environment application requirements, however, NTP can
generally maintain time to within tens of milliseconds over the public internet.
NTP isdefined inthe RFC5905: Network Time Protocol Version4: Protocol and Algorithms
Specification
Junos devices can be configured to act as an NTP client, a secondary NTP server, or a
primary NTP server. These variations are as follows:
•
Primary NTP Server—Primary NTP servers are synchronized to a reference clock that
is directly traceableto UTC. These servers then re-distribute thistime data downstream
to other Secondary NTP servers or NTP clients.
•
Secondary NTP Server—Secondary NTP servers are synchronized to a primary or
secondary NTP server. These servers then re-distribute this data downstream to other
Secondary NTP servers or NTP clients.
Time Management Administration Guide for Routing Devices
•
NTP Client—NTP clients aresynchronizedto aprimary or secondaryNTP server.Clients
do not re-distribute this time data to other devices.
NOTE: The NTP subnet includes a number of widely accessible public primary
time servers that can be used as a network’s primary NTP server. Juniper
Networks strongly recommends that you authenticate any primary servers
you use.
Each device on your network can be configured to run in one or more of the following
NTP modes:
•
Broadcast Mode—One or more devices is set up to transmit time information to a
specified broadcast or multicast address. Other devices listen time sync packets on
these addresses. This mode is less accurate than the client/server mode.
•
Client/Server Mode—Devices are organized hierarchically across the network in
client/server relationships.
NOTE: QFX devices cannot be act as NTP servers, only clients.
•
Symmetric Active (peer) Mode—Two or more devices are configured as NTP server
peers to provide redundancy.
By default, if an NTP client time drifts so that the difference in time from the NTP server
exceeds 128 milliseconds, the NTP client is automatically stepped back into
synchronization. The NTP client will still synchronize with the server even if the offset
betweenthe NTP client and server exceeds the 1000-secondthreshold.You can manually
request that adevice synchronize with an NTP serverby using the set datentp operational
command on the router. On devices running Junos OS that have dual Routing Engines,
the backup Routing Engine synchronizes directly with the master Routing Engine.
For more details on the Network Time Protocol, go to the Network Time Foundation
website at http://www.ntp.org.
NOTE: NTP is required for Common Criteria compliance. For more information
on the Common Criteria certification, see Public Sector Certifications.
In Junosoperating system (Junos OS) Release 11.2or later, NTPsupports IPv4VPN routing
and forwarding (VRF) requests. This enables an NTP server running on a provider edge
(PE) router to respond to NTP requests from a customer edge (CE) router. As a result,
a PE router can process anyNTP request packet coming fromdifferent routing instances.
In Junos OS Release 11.4 and later, NTP also supports IPv6 VRF requests.
Related
Documentation
Synchronizing and Coordinating Time Distribution Using NTP on page 13•
• Example: Configuring NTP as a Single Time Source for Router and Switch Clock
Synchronization on page 17
Understanding NTP Time Servers
The IETF defined the NetworkTime Protocol(NTP) tosynchronize the clocks ofcomputer
systems connected to each other over a network. Most large networks have an NTP
server that ensures that time on all devices is synchronized, regardless of the device
location. If you useone or more NTP servers on your network, ensure you include the NTS
server addresses in your Junos OS configuration.
When configuring the NTP, you can specify which system on the network is the
authoritative time source, or time server, and how time is synchronized between systems
on the network. To do this, you configure the router, switch, or security device to operate
in one of the following modes:
•
Client mode—In this mode, the local router or switch can be synchronized with the
remote system, but the remote system cannever be synchronized with thelocal router
or switch.
•
Symmetricactive mode—Inthis mode,the local router orswitch andthe remote system
can synchronize with each other. You use this mode in a network in which either the
local router or switch or the remote system might be a better source of time.
•
Broadcast mode—In this mode, the local router or switch sends periodic broadcast
messages to a client population at the specified broadcast or multicast address.
Normally, you include this statement only when the local router or switch is operating
as a transmitter.
•
Server mode—In this mode, the local router or switch operates as an NTP server.
NOTE: Symmetric active mode can be initiated by either the local or the
remote system. Only one system needs to be configured to do so. This
means that the local system can synchronize with any system that offers
symmetric active mode without any configuration whatsoever. However,
we strongly encourage you to configure authentication to ensure that the
local system synchronizes only with known time servers.
Time Management Administration Guide for Routing Devices
NOTE: In NTP server mode, the Junos OS supports authentication as
follows:
•
If the NTP request from the client comes with an authentication key
(such as a key ID and message digest sent with the packet), the request
is processed and answered based on the authentication key match.
•
If the NTP request from the client comes without any authentication key,
the request is processed and answered without authentication.
Related
Documentation
• Configuring the NTP Time Server and Time Services
• Example: Configuring NTP as a Single Time Source for Router and Switch Clock
Modifying the Default Time Zone for a Router or Switch Running Junos OS on page 12
•
Synchronizing and Coordinating Time Distribution Using NTP on page 13
•
Configuring the NTP Time Server and Time Services on page 14
•
Example: Configuring NTP as a Single Time Source for Router and Switch Clock
Synchronization on page 17
•
Configuring NTP Authentication Keys on page 18
•
Configuring the Router or Switch to Listen for Broadcast Messages Using
NTP on page 19
•
Configuring the Router or Switch to Listen for MulticastMessagesUsing NTP on page 19
•
Updating the IANA Time Zone Database on Junos Devices on page 20
Setting the Date and Time Locally
You can set the device time on the command-line using the set date operational
command:
To set the time in your Junos OS device, you can either configure it manually, or your
device can take a system time from an Network Time Protocol (NTP) server. If you do
not have access to an NTP server, you can configure Junos OS to keep its own local time
using an onboard clock.
To set time locally:
1. From operational mode, manually set the date and time.
Because this is an operational-mode command, there is noneed to perform a commit
operation.
user@host> set date YYYYMMDDhhmm.ss
For example:
user@host> set date 201307251632
Thu Jul 25 16:32:00 PDT 2013