HP AP775A Cisco MDS 9000 Family Fabric Manager Configuration Guide - Release 4 - Page 288

NTP Configuration Chapter 12 Initial Configuration Send documentation comments to [email protected] Note If you do not enter a time zone, GMT is used as the default. Step 5 Click the Apply Changes icon. . Note The date and time changes are saved across system resets. Note CFS does not support daylight savings time because a single fabric can span multiple time zones; every switch must be configured individually. If you want to configure daylight savings time on multiple switches simultaneously, see the RUN CLI command feature in the Cisco MDS 9000 Family Fabric Manager Configuration Guide. NTP Configuration A Network Time Protocol (NTP) server provides a precise time source (radio clock or atomic clock) to synchronize the system clocks of network devices. NTP is transported over User Datagram Protocol UDP/IP. All NTP communications use Universal Time Coordinated (UTC). An NTP server receives its time from a reference time source, such as a radio clock or atomic clock, attached to the time. NTP distributes this time across the network. This section includes the following sections: • About NTP, page 12-4 • NTP Configuration Guidelines, page 12-5 • Configuring NTP, page 12-6 • Editing an NTP Server or Peer Configuration, page 12-6 • Deleting an NTP Server or Peer, page 12-7 • NTP CFS Distribution, page 12-8 About NTP In a large enterprise network, having one time standard for all network devices is critical for management reporting and event logging functions when trying to correlate interacting events logged across multiple devices. Many enterprise customers with extremely mission-critical networks maintain their own stratum-1 NTP source. Time synchronization happens when several frames are exchanged between clients and servers. The switches in client mode know the address of one or more NTP servers. The servers act as the time source and receive client synchronization requests. By configuring an IP address as a peer, the switch will obtain and provide time as required. The peer is capable of providing time on its own and is capable of having a server configured. If both these instances point to different time servers, your NTP service is more reliable. Thus, even if the active server link is lost, you can still maintain the right time due to the presence of the peer. 12-4 Cisco MDS 9000 Family Fabric Manager Configuration Guide OL-17256-03, Cisco MDS NX-OS Release 4.x