KB.15.15

• In unicast mode: The trusted key is associated with a specific NTP/SNTP server, and configured

on the switch so that the SNTP client communicates with the server to get the date and time.

The key is used for authenticating the SNTP packet.

• In broadcast mode: The SNTP client switch checks the size of the received packet to determine

if it is authenticated. If the broadcast packet is authenticated, the key-id value is checked to

see if the same key-id value is configured on the SNTP client switch. If the switch is configured

with the same key-id value, and the key-id value is configured as "trusted," the authentication

succeeds. Only trusted key-id value information is used for SNTP authentication.

Syntax

sntp authentication key-id <key-id> trusted

Syntax

no sntp authentication key-id <key-id> trusted

Trusted keys are used during the authentication process. You can configure the switch with up to

eight sets of key-id/key-value pairs. One specific set must selected for authentication; this is done

by configuring the set as trusted.

The key-id itself must already be configured on the switch. To enable authentication, at least one

key-id must be configured as trusted.

The no version of the command indicates the key is unreliable (not trusted).

Default: No key is trusted by default.

Associating a key with an SNTP server

Syntax

[no] sntp server priority 1-3 [<ip-address> | <ipv6-address>]

<version-num> [ key-id <1-4,294,967,295> ]

Configures a to be associated with a specific server. The key itself must already be

configured on the switch.

The no version of the command disassociates the key from the server. This does

not remove the authentication key.

Default: No key is associated with any server by default.

• priority

Specifies the order in which the configured servers are polled for getting the

time.

• version-num

Specifies the SNTP software version to use and is assigned on a per-server

basis. The version setting is backwards-compatible. For example, using version

3 means that the switch accepts versions 1 through 3. Default: 3; range: 1 -

• key-id

Optional command. The key identifier sent in the SNTP packet. This key-id

is associated with the SNTP server specified in the command.

Configuring the key-identifier, authentication mode, and key-value 51