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Table Of Contents
NTP Commands on Cisco IOS XR Software
NTP Commands on Cisco IOS XR Software
This chapter describes the Cisco IOS XR Network Time Protocol (NTP) commands used to perform basic network time management tasks, including synchronizing time settings and coordinating time distribution over the network.
When an NTP server or client is configured, NTP features are available on all router interfaces. NTP features can be disabled for any specified interface, local or remote, to the route processor (RP).
For detailed information about NTP concepts, configuration tasks, and examples, see the Implementing NTP on Cisco IOS XR Software module in Cisco IOS XR System Management Configuration Guide.
access-group (NTP)
To control access to Network Time Protocol (NTP) services for a networking device, use the access-group command in NTP configuration mode. To remove the access-group command from the configuration file and restore the system to its default condition with respect to this command, use the no form of this command.
access-group {peer | query-only | serve | serve-only} access-list-name
no access-group {peer | query-only | serve | serve-only}
Syntax Description
Defaults
No NTP access control is configured.
Command Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The access group options are scanned in the following order from least restrictive to most restrictive:
1.
peer
2.
3.
4.
Access is granted for the first match that is found. If no access groups are specified, all access is granted to all sources. If any access groups are specified, only the specified access is granted. This facility provides minimal security for the time services of the system. However, it can be circumvented by a determined programmer. If tighter security is desired, use the NTP authentication facility.
Task ID
Examples
The following example shows how to configure the system to allow itself to be synchronized by a peer from an access list named access1 and to restrict access to allow only time requests from an access list named access2:
RP/0/RP0/CPU0:router(config-ntp)# access-group peer access1RP/0/RP0/CPU0:router(config-ntp)# access-group serve-only access2Related Commands
authenticate (NTP)
To enable Network Time Protocol (NTP) authentication, use the authenticate command in NTP configuration mode. To restore the system to its default condition, use the no form of this command.
authenticate
no authenticate
Syntax Description
This command has no arguments or keywords.
Defaults
No NTP authentication is configured.
Command Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the authenticate command to enable NTP authentication. When NTP authentication is enabled, the system does not synchronize to a time source unless it carries one of the authentication keys specified by the trusted-key command. Packets failing the authentication check are dropped.
Task ID
Examples
The following example shows how to configure the system to synchronize only to a system that provides an authentication key 42 in its NTP packets:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# authenticateRP/0/RP0/CPU0:router(config-ntp)# authentication-key 42 md5 clear key1RP/0/RP0/CPU0:router(config-ntp)# trusted-key 42Related Commands
Defines an authentication key for NTP.
Designates the key or keys to be trusted.
authentication-key (NTP)
To define an authentication key for a trusted Network Time Protocol (NTP) time source, use the authentication-key command in NTP configuration mode. To restore the system to its default condition, use the no form of this command.
authentication-key key-number md5 [clear | encrypted] key-name
no authentication-key key-number
Syntax Description
Defaults
No authentication key is defined for NTP.
Command Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the authentication-key command to define authentication keys for use with trusted NTP time sources.
Note
Task ID
Examples
The following example shows how to configure the system to synchronize only to systems providing authentication key 42 in their NTP packets:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# authenticateRP/0/RP0/CPU0:router(config-ntp)# authentication-key 42 md5 clear key1RP/0/RP0/CPU0:router(config-ntp)# trusted-key 42Related Commands
broadcast
To create a Network Time Protocol (NTP) broadcast server on a specified NTP interface, use the broadcast command in NTP interface configuration mode. To remove the broadcast command from the configuration file and restore the system to its default condition, use the no form of this command.
broadcast [destination ip-address] [key key-id] [version number]
no broadcast [destination ip-address] [key key-id] [version number]
Syntax Description
Defaults
No NTP broadcast servers are configured.
Command Modes
NTP interface configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the broadcast command to create an NTP broadcast server on an NTP interface to send NTP broadcast packets.
Use the broadcast client command to set a specific interface to receive NTP broadcast packets.
Task ID
Examples
The following example shows how to configure Packet-over-SONET/SDH (POS) interface 0/0/0/1 to send NTP packets to destination host IP address 10.0.0.0:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# interface POS 0/0/0/1RP/0/RP0/CPU0:router(config-ntp-int)# broadcast destination 10.0.0.0Related Commands
Allows a networking device to receive NTP broadcast packets on an interface.
Sets the estimated round-trip delay between the software and an NTP broadcast server.
broadcast client
To allow a networking device to receive Network Time Protocol (NTP) broadcast packets on an interface, use the broadcast client command in NTP interface configuration mode. To remove the configuration and restore the system to its default condition, use the no form of this command.
broadcast client
no broadcast client
Syntax Description
This command has no arguments or keywords.
Defaults
No NTP broadcast clients are configured.
Command Modes
NTP interface configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the broadcast client command to configure and create an NTP broadcast client and to associate the client with an interface to receive and handle NTP broadcast packets. If no NTP client has been created for an interface, the received NTP broadcast packets are dropped. Use this command to allow the system to listen to broadcast packets on an interface-by-interface basis.
Task ID
Examples
The following example shows how to configure Packet-over-SONET/SDH (POS) interface 0/0/0/1 to send NTP packets:
RP/0/RP0/CPU0:router(config)# ntp interface POS 0/0/0/1RP/0/RP0/CPU0:router(config-ntp-int)# broadcast clientRelated Commands
Creates an NTP broadcast server on a specified NTP interface.
Sets the estimated round-trip delay between the software and an NTP broadcast server.
broadcastdelay
To set the estimated round-trip delay between a Network Time Protocol (NTP) client and an NTP broadcast server, use the broadcastdelay command in global configuration mode. To restore the system to its default condition, use the no form of this command.
broadcastdelay microseconds
no broadcast microseconds
Syntax Description
microseconds
Estimated round-trip time (in microseconds) for NTP broadcasts. The range is from 1 to 999999. The default is 3000 microseconds.
Defaults
microseconds: 3000 microseconds
Command Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the broadcastdelay command to change the default round-trip delay time on a networking device that is configured as a broadcast client.
Task ID
Examples
The following example shows how to set the estimated round-trip delay between a networking device and the broadcast client to 5000 microseconds:
RP/0/RP0/CPU0:router(config-ntp)# broadcastdelay 5000interface (NTP)
To configure a Network Time Protocol (NTP) interface, use the interface command in NTP configuration mode. To disable an NTP interface, use the no form of this command.
interface type interface-id [disable]
Syntax Description.
Defaults
No NTP interfaces are configured.
Command Modes
NTP interface configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the interface (NTP) command to place the router in NTP interface configuration mode, from which NTP broadcast servers and broadcast clients can be configured. By default, after the NTP process is started, NTP features become available for all interfaces. To exit NTP interface configuration mode, use the exit command.
Task ID
Examples
The following example shows how to enter NTP configuration mode, specify an NTP interface to be configured, and enter NTP interface configuration mode:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# interface POS 0/1/0/0RP/0/RP0/CPU0:router(config-ntp-int)master
To configure the router to use its own Network Time Protocol (NTP) master clock to synchronize with peers when an external NTP source becomes unavailable, use the master command in NTP configuration mode. To restore the system to its default condition, use the no form of this command.
master [stratum]
no master [stratum]
Syntax Description
stratum
(Optional) NTP stratum number that the system claims. Range is from 1 to 15. The default is 8.
Defaults
By default, the master clock function is disabled. When the function is enabled, the default stratum is 8.
Command Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
NTP uses the concept of a "stratum" to describe how many NTP "hops" away a machine is from an authoritative time source. A stratum 1 time server has a radio or atomic clock attached directly. A stratum 2 time server receives its time through NTP from a stratum 1 time server, a stratum 3 from a stratum 2, and so on.
Caution
The networking device is normally synchronized, directly or indirectly, with an external system that has a clock. The Cisco IOS XR software does not support directly attached radio or atomic clocks. The master command should be used only when there is a temporary disruption in a reliable time service. It should not be employed as an alternative source by itself in the absence of a real-time service.
If the system has the master command configured and it cannot reach any clock that has a lower stratum number, the system claims to be synchronized at the configured stratum number. Other systems synchronize with it through NTP.
Note
Task ID
Examples
The following example shows how to configure a networking device as an NTP master clock to which peers may synchronize:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# master 9max-associations
To set the maximum number of Network Time Protocol (NTP) associations, use the max-associations command in NTP configuration mode. To restore the default setting, use the no form of this command.
max-associations number
no max-associations number
Syntax Description
Defaults
The default setting for the maximum number of NTP associations is 100.
Command Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the max-associations command to specify the maximum number of associations for an NTP server.
Task ID
Examples
The following example shows how to set the maximum number of associations to 200:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# max-associations 200Related Commands
ntp
To enter Network Time Protocol (NTP) configuration mode and run NTP configuration commands, use the ntp command in global configuration mode
ntp
Syntax Description
This command has no arguments or keywords.
Defaults
No defaults behavior or values
Command Modes
Global configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
NTP configuration commands can also be run from global configuration mode by preceding the command string with the ntp keyword. From NTP configuration mode, the following NTP configuration commands are available:
RP/0/RP0/CPU0:router(config-ntp)# ?access-group Control NTP accessauthenticate Authenticate time sourcesauthentication-key Authentication key for trusted time sourcesbroadcastdelay Estimated round-trip delaycommit Commit the configuration changes to runningdefault Set a command to its defaultsdescribe Describe a command without taking real actionsdo Run an exec commandexit Exit from this submodeinterface Configure NTP on an interfacemaster Act as NTP master clockmax-associations Set maximum number of associationsno Negate a command or set its defaultspeer Configure NTP peerport Enable NTP portserver Configure NTP servershow Show contents of configurationsource Configure interface for source addresstrusted-key Key numbers for trusted time sourcesupdate-calendar Periodically update calendar with NTP timeTask ID
Examples
The following example shows how to enter NTP configuration mode:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)#ntp clear
To clear all Network Time Protocol (NTP) peers or a specific NTP peer, use the ntp clear command in EXEC mode.
ntp clear {peer | *}
Syntax Description
Defaults
No defaults behavior or values
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Task ID
Examples
The following example shows how to clear all NTP peers:
RP/0/RP0/CPU0:router# ntp clear *peer (NTP)
To configure the system clock to synchronize a peer or to be synchronized by a peer, use the peer command in NTP configuration mode. To remove the peer command from the configuration file and restore the system to its default condition with respect to the command, use the no form of this command.
peer ip-address [version number] [key key-id] [minpoll interval] [maxpoll interval] [source interface-type interface-id] [prefer]
no peer ip-address
Syntax Description
Defaults
No peers are configured by default. If a peer is configured, the default NTP version number is 4, no authentication key is used, and the source IP address is taken from the outgoing interface.
minpoll interval: 6 seconds
maxpoll interval: 10 secondsCommand Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the peer (NTP) command to allow this machine to synchronize with the peer, or conversely.
Caution
The value for the minpoll keyword must be less than or equal to the value for the maxpoll keyword. If this is not the case, the system issues an error message.
To provide peer-level service (as opposed to client/server-level service), it may be necessary to explicitly specify the NTP version for the peer if it is not version 4.
Task ID
Examples
The following example shows how to configure a networking device to allow its system clock to be synchronized with the clock of the peer (or conversely) at IP address 10.0.0.0 using NTP. The source IP address is the address of Packet-over-SONET/SDH (POS) interface 0/0/0/1.
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# peer 10.0.0.0 minpoll 8 maxpoll 12 source POS 0/0/0/1Related Commands
Defines an authentication key for NTP.
Allows the system clock to be synchronized by a time server.
Uses a particular source address in NTP packets.
server (NTP)
To allow the system clock to be synchronized by a time server, use the server command in NTP configuration mode. To remove the server command from the configuration file and restore the system to its default condition with respect to this command, use the no form of this command.
server ip-address [version number] [key key-id] [minpoll interval] [maxpoll interval] [source interface-type interface-id] [prefer]
no server ip-address
Syntax Description
Defaults
No servers are configured by default. If a server is configured, the default NTP version number is 4, no authentication key is used, and the source IP address is taken from the outgoing interface.
minpoll interval: 6 seconds
maxpoll interval: 10 secondsCommand Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The value for the minpoll keyword must be less than or equal to the value for the maxpoll keyword. If this is not the case, the system issues an error message.
Using the prefer keyword reduces switching back and forth among servers.
Task ID
Examples
The following example shows how to configure a router to allow its system clock to be synchronized with the clock of the peer at IP address 209.165.201.1 using NTP:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# server 209.165.201.1 minpoll 8 maxpoll 12Related Commands
Defines an authentication key for NTP.
Configures the system clock to synchronize a peer or to be synchronized by a peer.
Uses a particular source address in NTP packets.
show calendar
To display the system time and date, use the show calendar command in EXEC mode.
show calendar
Syntax Description
This command has no keywords or arguments.
Defaults
No defaults behavior or values
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the show calendar command to display the time and date in Coordinated Universal Time (UTC) format.
Task ID
Examples
The following is sample output from the show calendar command:
RP/0/RP0/CPU0:router# show calendar01:29:28 UTC Thu Apr 01 2004Related Commands
show ntp associations
To display the status of Network Time Protocol (NTP) associations, use the show ntp associations command in privileged EXEC mode.
show ntp associations [detail] [location node-id]
Syntax Description
Defaults
No defaults behavior or values
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Task ID
Examples
The following is sample output from the show ntp associations command:
RP/0/RP0/CPU0:router# show ntp associationsaddress ref clock st when poll reach delay offset disp*~172.19.69.1 171.68.10.150 2 4 64 3 2.0 -3.79 0.0* master (synced), # master (unsynced), + selected, - candidate, ~configuredTable 62 describes the significant fields shown in the display.
The following is sample output from the show ntp associations detail command:
RP/0/RP0/CPU0:router# show ntp associations detail172.19.69.1 configured, our_master, sane, valid, stratum 2ref ID 171.68.10.150, time C4143AAE.00FCF396 (18:27:58.003 UTC Tue Mar 30 2004)our mode client, peer mode server, our poll intvl 64, peer poll intvl 64root delay 5.23 msec, root disp 4.07, reach 3, sync dist 0.0077delay 1.9829 msec, offset -3.7899 msec, dispersion 0.0358precision 2**18, version 4org time C4143B8D.7EBD5FEF (18:31:41.495 UTC Tue Mar 30 2004)rcv time C4143B8D.801DFA44 (18:31:41.500 UTC Tue Mar 30 2004)xmt time C4143B8D.7F595E44 (18:31:41.497 UTC Tue Mar 30 2004)filtdelay = 2.99 1.98 1.98 1.99 1.99 1.99 2.98 1.98filtoffset = -3.89 -3.74 -3.78 -3.81 -3.76 -3.73 -4.08 -3.64filterror = 0.00 0.02 0.03 0.05 0.06 0.08 0.09 0.32Table 63 describes the significant fields shown in the display.
Related Commands
show ntp status
To display the status of Network Time Protocol (NTP), use the show ntp status command in EXEC mode.
show ntp status [location node-id]
Syntax Description
location node-id
(Optional) Displays the status of NTP from the designated node. The node-id argument is entered in the rack/slot/module notation.
Defaults
No defaults behavior or values
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Task ID
Examples
The following is sample output from the show ntp status command:
RP/0/0/CPU0:router# show ntp status location 0/2/cpu0Clock is synchronized, stratum 4, reference is DLRSC nodenominal freq is 1000.0000 Hz, actual freq is 999.9801 Hz, precision is 2**26reference time is C4143841.3403218C (18:17:37.203 UTC Tue Mar 30 2004)clock offset is -11.9957 msec, root delay is 11.41 msecroot dispersion is 65.94 msec, peer dispersion is 0.00 msecTable 64 describes the significant fields shown in the display.
Related Commands
source (NTP)
To use a particular source address in Network Time Protocol (NTP) packets, use the source command in NTP configuration mode. To remove the source command from the configuration file and restore the system to its default condition, use the no form of this command.
source interface-type interface-id
no source
Syntax Description
Defaults
The source address is determined by the outgoing interface.
Command Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the source command to use a particular source IP address for all NTP packets. The address is taken from the named interface. This command is useful if the address on an interface cannot be used as the destination for reply packets. If the source keyword has been configured with the server (NTP) or peer (NTP) command, that value overrides the global value.
Task ID
Examples
The following example shows how to configure the router to use the IP address of Packet-over-SONET/SDH (POS) interface 0/0/0/1 as the source address of all outgoing NTP packets:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# source POS 0/0/0/1Related Commands
Configures the system clock to synchronize a peer or to be synchronized by a peer.
Allows the system clock to be synchronized by a time server.
trusted-key
To designate a Network Time Protocol (NTP) trusted key, use the trusted-key command in NTP configuration mode. To remove the trusted-key command from the configuration file and restore the system to its default condition with respect to this command, use the no form of this command.
trusted-key key-number
no trusted-key key-number
Syntax Description
Defaults
No NTP trusted key is designated.
Command Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
If authentication is enabled, use the trusted-key command to define one or more key numbers (corresponding to the keys defined with the authentication-key [NTP] command) that a NTP system must provide in its NTP packets for this system to synchronize to it. Because the other system must know the correct authentication key, this precaution provides protection against accidentally synchronizing the system to a system that is not trusted.
Task ID
Examples
The following example shows how to configure the system to synchronize only to systems providing authentication key 42 in its NTP packets:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# authenticateRP/0/RP0/CPU0:router(config-ntp)# authentication-key 42 md5 clear key1RP/0/RP0/CPU0:router(config-ntp)# trusted-key 42Related Commands
update-calendar
To update the calendar periodically from Network Time Protocol (NTP), use the update-calendar command in NTP configuration mode. To remove the update-calendar command from the configuration file and restore the system to its default condition with respect to the command, use the no form of this command.
update-calendar
no update-calendar
Syntax Description
This command has no arguments or keywords.
Defaults
This command is disabled.
Command Modes
NTP configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Some networking devices have a calendar that is separate from the system clock. This calendar runs continuously, even if the device is powered off or rebooted.
If a networking device is synchronized to an outside time source through NTP, it is a good idea to update the calendar with the time learned from NTP. Otherwise, the calendar may gradually lose or gain time.
After you configure the ntp update calendar command, NTP updates the calendar with the system clock every hour.
Task ID
Examples
The following example shows how to configure the system to update the calendar periodically from the system clock:
RP/0/RP0/CPU0:router(config)# ntpRP/0/RP0/CPU0:router(config-ntp)# update-calendarRelated Commands
clock read-calendar
Copies the hardware (calendar) clock settings into the software clock.
clock update-calendar
Sets the calendar from the software clock.
