Configuring SNTP Settings

TejNOS-EN software supports the Simple Network Time Protocol (SNTP). SNTP assures accurate network device clock time synchronization up to the millisecond. Time synchronization is performed by a network SNTP server. TejNOS-EN software operates only as an SNTP client and cannot provide time services to other systems.

Time sources are established by Stratums. Stratums define the accuracy of the reference clock. The higher the stratum (where zero is the highest), the more accurate the clock. The device receives time from stratum 1 and above since it is itself a stratum 2 device.

The following is an example of stratums:

Stratum 0: A real time clock is used as the time source.
Stratum 1: A server that is directly linked to a Stratum 0 time source is used. Stratum 1 time servers provide primary network time standards.
Stratum 2: The time source is distanced from the Stratum 1 server over a network path.

Information received from SNTP servers is evaluated based on the time level and server type.

SNTP time definitions are assessed and determined by the following time levels:

T1: Time at which the original request was sent by the client.
T2: Time at which the original request was received by the server.
T3: Time at which the server sent a reply.
T4: Time at which the client received the server's reply.

The device can poll Unicast and Broadcast server types for the server time.

Polling for Unicast information is used for polling a server for which the IP address is known. SNTP servers that have been configured on the device are the only ones that are polled for synchronization information. T1 through T4 are used to determine server time. This is the preferred method for synchronizing device time because it is the most secure method. If this method is selected, SNTP information is accepted only from SNTP servers defined on the device using the SNTP Server Configuration page.

Broadcast information is used when the server IP address is unknown. When a Broadcast message is sent from an SNTP server, the SNTP client listens to the message. If Broadcast polling is enabled, any synchronization information is accepted, even if it has not been requested by the device. This is the least secure method.

The device retrieves synchronization information, either by actively requesting information or at every poll interval. If Unicast and Broadcast polling are enabled, the information is retrieved in this order:

Information from servers defined on the device is preferred. If Unicast polling is not enabled or if no servers are defined on the device, the device accepts time information from any SNTP server that responds.
If more than one Unicast device responds, synchronization information is preferred from the device with the lowest stratum.
If the servers have the same stratum, synchronization information is accepted from the SNTP server that responded first.

MD5 (Message Digest 5) Authentication safeguards device synchronization paths to SNTP servers. MD5 is an algorithm that produces a 128‐bit hash. MD5 is a variation of MD4, and increases MD4 security. MD5 verifies the integrity of the communication, authenticates the origin of the communication.

SNTP Global Configuration

Use the SNTP Global Configuration page to view and adjust SNTP parameters.

To display the SNTP Global Configuration page, click System > SNTP > Global Configuration in the navigation menu.

sntp_global

SNTP Global Configuration Fields

Field	Description
Client Mode	Use drop‐down list specify the SNTP client mode, which is one of the following modes: Disable: SNTP is not operational. No SNTP requests are sent from the client nor are any received SNTP messages processed. Unicast: SNTP operates in a point to point fashion. A unicast client sends a request to a designated server at its unicast address and expects a reply from which it can determine the time and, optionally the round‐trip delay and local clock offset relative to the server. Broadcast: SNTP operates in the same manner as multicast mode but uses a local broadcast address instead of a multicast address. The broadcast address has a single subnet scope while a multicast address has Internet wide scope.
Port	Specifies the local UDP port to listen for responses/broadcasts. Allowed range is (1 to 65535). Default value is 0.
Unicast Poll Interval	Specifies the number of seconds between unicast poll requests expressed as a power of two when configured in unicast mode. Allowed range is (6 to 10). Default value is 6.
Broadcast Poll Interval	Specifies the number of seconds between broadcast poll requests expressed as a power of two when configured in broadcast mode. Broadcasts received prior to the expiry of this interval are discarded. Allowed range is (6 to 10). Default value is 6.
Unicast Poll Timeout	Specifies the number of seconds to wait for an SNTP response when configured in unicast mode. Allowed range is (1 to 30). Default value is 5.
Unicast Poll Retry	Specifies the number of times to retry a request to an SNTP server after the first time‐out before attempting to use the next configured server when configured in unicast mode. Allowed range is (0 to 10). Default value is 1.

If you change any of the settings on the page, click Submit to apply the changes to system.

SNTP Global Status

Use the SNTP Global Status page to view information about the system’s SNTP client. To access the SNTP Global Status page, click System > SNTP > Global Status in the navigation menu.

sntp_global_status

Global Status Fields

Field	Description
Version	Specifies the SNTP Version the client supports.
Supported Mode	Specifies the SNTP modes the client supports. Multiple modes may be supported by a client.
Last Update Time	Specifies the local date and time (UTC) the SNTP client last updated the system clock.
Last Attempt Time	Specifies the local date and time (UTC) of the last SNTP request or receipt of an unsolicited message
Last Attempt Status	Specifies the status of the last SNTP request or unsolicited message for both unicast and broadcast modes. If no message has been received from a server, a status of Other is displayed. These values are appropriate for all operational modes: Other: None of the following enumeration values. Success: The SNTP operation was successful and the system time was updated. Request Timed Out: A directed SNTP request timed out without receiving a response from the SNTP server. Bad Date Encoded: The time provided by the SNTP server is not valid. Version Not Supported: The SNTP version supported by the server is not compatible with the version supported by the client. Server Unsynchronized: The SNTP server is not synchronized with its peers. This is indicated via the 'leap indicator' field on the SNTP message. Server Kiss Of Death: The SNTP server indicated that no further queries were to be sent to this server. This is indicated by a stratum field equal to 0 in a message received from a server.
Server IP Address	Specifies the IP address of the server for the last received valid packet. If no message has been received from any server, an empty string is shown.
Address Type	Specifies the address type of the SNTP Server address for the last received valid packet.
Server Stratum	Specifies the claimed stratum of the server for the last received valid packet.
Reference Clock Id	Specifies the reference clock identifier of the server for the last received valid packet.
Server Mode	Specifies the mode of the server for the last received valid packet.
Unicast Sever Max Entries	Specifies the maximum number of unicast server entries that can be configured on this client.
Unicast Server Current Entries	Specifies the number of current valid unicast server entries configured for this client.
Broadcast Count	Specifies the number of unsolicited broadcast SNTP messages that have been received and processed by the SNTP client since last reboot.

Click Refresh to display the latest information from the router.

SNTP Server Configuration

Use the SNTP Server Configuration page to view and modify information for adding and modifying Simple Network Time Protocol SNTP servers. To display the SNTP Server Configuration page, click System > SNTP > Server Configuration in the navigation menu.

sntp_server_config

SNTP Server Configuration Fields

Field	Description
Server	Select the IP address of a user‐defined SNTP server to view or modify information about an SNTP server, or select Create to configure a new SNTP server. You can define up to three SNTP servers.
Address / Hostname	Enter the IP address or the hostname of the SNTP server.
Address Type	Select IPv4 if you entered an IPv4 address, IPv6 if you entered an IPv6 address or DNS if you entered a hostname.
Port	Enter a port number from 1 to 65535. The default is 123.
Priority	Enter a priority from 1 to 3, with 1 being the highest priority. The switch will attempt to use the highest priority server and, if it is not available, will use the next highest server.
Version	Enter the protocol version number.

To add an SNTP server, select Create from the Server list, complete the remaining fields as desired, and click Submit. The SNTP server is added, and is now reflected in the Server list. You must perform a save to retain your changes over a power cycle.
To removing an SNTP server, select the IP address of the server to remove from the Server list, and then click Delete. The entry is removed, and the device is updated.

SNTP Server Status

The SNTP Server Status page displays status information about the SNTP servers configured on your switch. To access the SNTP Server Status page, click System > SNTP > Server Status in the navigation menu.

sntp_server_status

SNTP Server Status Fields

Field	Description
Address	Specifies all the existing Server Addresses. If no Server configuration exists, a message saying “No SNTP server exists” flashes on the screen.
Last Update Time	Specifies the local date and time (UTC) that the response from this server was used to update the system clock.
Last Attempt Time	Specifies the local date and time (UTC) that this SNTP server was last queried.
Last Attempt Status	Specifies the status of the last SNTP request to this server. If no packet has been received from this server, a status of Other is displayed: Other: None of the following enumeration values. Success: The SNTP operation was successful and the system time was updated. Request Timed Out: A directed SNTP request timed out without receiving a response from the SNTP server. Bad Date Encoded: The time provided by the SNTP server is not valid. Version Not Supported: The SNTP version supported by the server is not compatible with the version supported by the client. Server Unsynchronized: The SNTP server is not synchronized with its peers. This is indicated through the 'leap indicator' field on the SNTP message. Server Kiss Of Death: The SNTP server indicated that no further queries were to be sent to this server. This is indicated by a stratum field equal to 0 in a message received from a server.
Unicast Server Num Requests	Specifies the number of SNTP requests made to this server since last agent reboot.
Unicast Server Num Failed Requests	Specifies the number of failed SNTP requests made to this server since last reboot.

Click Refresh to display the latest information from the switch.