Brocade VDX 6710-54 Hardware Reference Manual - Manual (Page 35)

Brocade VDX 6710-54 Hardware Reference Manual 17
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Setting the date and time
3
Setting the date and time
The Brocade VDX 6710-54 maintains the current date and time inside a battery-backed real-time
clock (RTC) circuit. Date and time are used for logging events. Switch operation does not depend on
the date and time; a Brocade VDX 6710-54 with an incorrect date and time value functions
properly. Because the date and time are used for logging, error detection, and troubleshooting, you
should set them correctly.
Understanding time zones
You can set the time zone for a switch by using the clock TimeZone command. The time zone
setting has the following characteristics:
• The clock TimeZone setting automatically adjusts for Daylight Savings Time.
• Changing the time zone on a switch updates the local time zone setup and is reflected in local
time calculations.
• By default, all switches are in the Greenwich Mean Time (GMT) time zone (0,0). If all switches
in a fabric are in one time zone, it is possible for you to keep the time zone setup at the default
setting.
• System services that have already started will reflect the time zone changes only after the next
reboot.
• Time zone settings persist across failover for high availability.
• Time zone settings are not affected by Network Time Protocol (NTP) server synchronization.
The following regions are supported: Africa, America, Antarctica, Asia, Atlantic, Australia, Europe,
Indian, and Pacific. One of these, along with a city name, establishes the time zone.
Understanding time synchronization
To keep the time in your network current, it is recommended that the principal switch has its time
synchronized with at least one external NTP server. The other switches in the fabric will
automatically take their time from the principal switch.
All switches in the fabric maintain the current clock server value in nonvolatile memory. By default,
this value is the local clock server of the principal switch. Changes to the clock server value on the
principal switch are propagated to all switches in the fabric.
When a new switch enters the fabric, the time server daemon of the principal switch sends out the
addresses of all existing clock servers and the time to the new switch.
The ntp server command accepts multiple server addresses in IPv4 format. When multiple NTP
server addresses are passed, ntp server sets the first obtainable address as the active NTP server.
If there are no reachable time servers, then the local switch time is the default time.