Description                                                    Configure Network Time Protocol (NTP) parameters.

Syntax                                                                  [no] ntp allow-data-ports

Syntax                                                                  [no] ntp auth-key {M | SHA | SHA1} [hex] string

Syntax                                                                  [no] ntp trusted-key ID-num 

Syntax                                                                  [no] ntp server {hostname | ipaddr}

The ntp server command changes the CLI to the configuration level for the server, where the following commands are available.




Allow connections to NTP servers from data ports.


Disables synchronization with the NTP server.


Enables synchronization with the NTP server.

key ID-num

Creates an authentication key. For ID-num, enter a value between 1-65535.


Directs ACOS to use this NTP server by default. Additional NTP servers are used as backup servers if the preferred NTP server is unavailable.

{M | SHA | SHA1}
ascii | hex} string

Specifies the type of authentication key you want to create for authenticating the NTP servers.

  M - encryption using MD5

  SHA - encryption using SHA

  SHA1 - encryption using SHA1

Specify the authentication key string (1-20 characters. Use the hex parameter to specify the string in hex format (21-40 characters), or ascii to specify it in text.

trusted-key ID-num

Adds an authentication key to the list of trusted keys. For num, enter the identification number of a configured authentication key to add the key to the trusted key list. You can enter more than one number, separated by whitespace, to simultaneously add multiple authentication keys to the trusted key list.

Default                                                                NTP synchronization is disabled by default. If you enable it, DST is enabled by default, if appli­cable to the specified timezone.

Mode                                                                   Configuration mode

Usage                                                                  You can configure a maximum of 4 NTP servers.

If the system clock is adjusted while OSPF or IS-IS is enabled, the routing protocols may stop working properly. To work around this issue, disable OSPF and IS-IS before adjusting the system clock.

Example                                                            The following commands configure an NTP server and enable NTP:

ACOS(config)#ntp server

ACOS(config)#ntp server enable


Example                                                            The following example creates 3 authentication keys (1337 using MD5 encryption, 1001 using SHA encryption, and 1012 using SHA1 encryption) and adds these keys to the list of trusted keys. The NTP server located at is configured to use a trusted key (1337) for authentication:

ACOS(config)#ntp auth-key 1337 M XxEnc192

ACOS(config)#ntp auth-key 1001 SHA Vke1324as

ACOS(config)#ntp auth-key 1012 SHA1 28fj039

ACOS(config)#ntp trusted-key 1337 1001 1012

ACOS(config)#ntp server key 1337


You can verify the NTP server and authentication key configuration with the show run command. The following example includes an output modifier to display only NTP-related configuration:

ACOS(config)#show run | include ntp

ntp auth-key 1001 SHA encrypted FSNiuf10Dtzc4aY0tk2J4DwQjLjV2wDnPBCMuNXbAOc8EIy41dsA5zwQjLjV2wDn

ntp auth-key 1012 SHA1 encrypted NEMuh8GgapM8EIy41dsA5zwQjLjV2wDnPBCMuNXbAOc8EIy41dsA5zwQjLjV2wDn

ntp auth-key 1337 M encrypted zIJptJHuaQaw/5o10esBTDwQjLjV2wDnPBC­MuNXbAOc8EIy41dsA5zwQjLjV2wDn

ntp trusted-key 1001 1012 1337

ntp server key 1337

ntp server enable

Table of Contents