You can manually configure the time and daylight saving time on the switch, or you can
configure NTP so that the switch requests time updates from an NTP server or receives
updates automatically from an NTP broadcast server.
Note: If you are configuring system time using Cluster Management
software, your changes on this window are implemented for the entire cluster. If you are
configuring system time using Visual Switch Manager (even if the switch belongs to a
cluster), your change applies to the local switch only.
The Set Current Time tab of the System Time Management window automatically displays
the current time: hours (in 24-hour format), minutes, seconds, milliseconds, time zone,
week day name, month, day date, and year.
Generally, you do not need to set the system clock if the system is synchronized by a
valid outside timing mechanism such as NTP. If no other time source is available, you
should manually set the time. The time specified is relative to the configured time zone.
To manually set the system time:
Select the Set Current Time tab from the System Time Management window.
In the Set System Time Manually section, select the correct month, day, and year from
the drop-down lists.
Select the correct hour, minutes, and seconds from the drop-down lists.
Your hour selection must be based on 24-hour format. For example, for 9 A.M., enter 09;
for 1 P.M.., enter 13; for midnight, enter 24.
In the UTC Offset section, select the hours offset from the Hours Offset from UTC
drop-down list.
Universal Time Coordinated (UTC) is the same as Greenwich Mean time. The offset
(difference between UTC and the time zone of the switch) can be a negative or positive
number. For example, Pacific Standard Time has an offset of -8 hours, meaning it is 8
hours behind UTC.
Select the minutes offset from the Minutes Offset from UTC drop-down list. Note: If hours are negative, minutes are assumed to be negative.
In the Name of the Time Zone field, enter the name of the zone to be displayed when
standard time is in effect.
For example, enter PST for Pacific Standard Time.
Click Apply to put your changes on this tab in effect.
The Set Daylight Saving Time tab configures summertime or daylight saving time for
three conditions:
Daylight saving time does not apply to your area.
Daylight saving time starts and ends on a particular day of the week each year
(recurring pattern).
Daylight saving time starts and ends on an exact date and time.
By default, the switch does not adjust for daylight saving time. To configure
daylight saving time:
In the Name of the Summer Time Zone field, enter the name of the time zone to be
displayed when summer or daylight time is in effect.
For example, enter PDT for Pacific Daylight Time.
From the Minutes to Add During Summer Time drop-down list, select the number of
minutes to set the clock forward for summer or daylight time.
The default is 60 minutes.
Configure the switch as an NTP client if you want it to regularly send time-of-day
requests to an NTP server (or, see Configuring the Switch as an NTP
Broadcast Client). The NTP server then synchronizes the client system clock to the
clock on the server when the switch requests it. To enhance security, you can configure
NTP authentication (see Configuring NTP
Authentication).
To configure your switch to receive time updates from an NTP server:
Select the Network Time Protocol tab on the System Time Management
Window.
In the IP Address field of the NTP Server section, enter the IP address of the time
server.
You can configure up to 10 server addresses per client.
(Optional) In the Ver (version) field, enter the NTP version number.
You can enter a number from 1 to 3; the default is version 3. Note: If you are using the default version (3) and NTP synchronization
does not occur, try using NTP version 2. Many NTP servers on the Internet run version 2.
(Optional) In the Key ID field, enter the authentication key to use when sending packets
to the server (if authentication is enabled).
Enter a number from 0 to 4294967295. The default is 0, which means that authentication is
not in effect. If authentication is disabled, the system clock on the client switch is
updated.
(Optional) Select the Preferred Server checkbox if you want this server
to be the preferred server for synchronization.
Selecting a preferred server reduces the switching back and forth among servers if
multiple NTP servers are configured.
Click Add to add the server address to the list box.
(To remove an NTP server address from this list, select the address from the list box and
click Remove.)
Repeat this procedure to add more NTP servers.
Click Apply to put your changes on this tab in effect.
Click OK to close the System Time Management window.
Authentication enhances the security of a system running the NTP protocol. When NTP
authentication is set, the switch updates the time only from servers that provide the
correct authentication. By default, NTP authentication is disabled.
The authentication scheme designed for NTP uses the public-key cryptography with the
Message Digest (MD5) algorithm. With this scheme, every message must be individually
signed using an authentication key. The key consists of two parts: a public key number (a
32-bit integer) and a secret key value (an arbitrary string of up to 32 characters). To
authenticate a message, the client must have the authentication key (public/secret key
pair) matched with the one on the server. Therefore, the authentication key must be
securely distributed in advance; the client administrator must obtain the key pair from
the server administrator and configure it on the client. The public key is known as the
key identifier and key number. The secret key is known as the key value.
Note: For authentication to work properly, you must obtain the key
information from the server administrator in advance and enter it in the NTP
Authentication field.
To enable authentication:
Deselect Authentication Disabled above the NTP Authentication section.
In the Key Number field of the NTP Authentication section, enter a public key number.
Enter a number from 1 to 4294967295.
In the Key Value field, enter the secret key.
Enter up to 32 printable characters, including alphanumeric keys, plus spaces, including
!, ", #, $, }, |, ~, and so forth. No control or escape characters are allowed. Note: The switch can store a maximum of 10 authentication keys at a time.
(Optional) In the Encryption Type field, enter the number used to encrypt the key value.
Enter a number from 0 to 4294967295.
(Optional) Select the Trusted checkbox if you want the authentication
key to be trusted.
This setting defines one or more key numbers that an NTP server must provide in its
packets for the client system to synchronize its clock to the server clock. A trusted
server provides protection against accidentally synchronizing the client clock to a system
that does not have the correct authentication key.
Click Add to add the key to the list box.
Repeat this procedure to add more authentication keys.
Click Apply to put your changes on this tab in effect.
Click OK to close the System Time Management window.
To remove authentication information, select it in the list box and click Remove.
Configure the switch as an NTP broadcast client if an NTP broadcast server, such as a
router, regularly broadcasts time-of-day information over the network (also see Configuring the Switch as an NTP Client).
To compensate for any server-to-client packet latency, you can specify an estimated NTP
broadcast delay (a time adjustment factor for receiving broadcast packets from the
server). By default, the NTP broadcast client is disabled on the switch.
To configure your switch to receive NTP broadcast packets on an interface:
Select the Received NTP Broadcast Client checkbox.
(Optional) In the Estimated Round-Trip Delay field, enter a number from 1 to 999999
(microseconds).
The default is 3000 microseconds. This number is the estimated round-trip delay between
the client and the NTP broadcast server.
Click Apply to put your changes on this tab in effect.
Click OK to close the System Time Management window.