Dynabrade Dynabug 57810, Руководство пользователя

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NOTE: NTP is required for Common Criteria compliance. For more information
on the Common Criteria certification, see Public Sector Certifications .
In Junos operating system (Junos OS) Release 11.2 or later, NTP supports IPv4 VPN 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 any NTP request packet coming from different 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
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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 Network Time Protocol (NTP) to synchronize the clocks of computer
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 use one 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 can never be synchronized with the local router
or switch.
• Symmetric active mode—In this mode, the local router or switch and the 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.
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.
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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.
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Server mode—In this mode, the local router or switch operates as an NTP server.
5 Copyright © 2014, Juniper Networks, Inc.
Chapter 1: Time Management Overview