Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 1009

time and adjust the local clock accordingly. In addition, the message includes information to calculate the expected timekeeping accuracy and reliability, as well as select the best from possibly several servers. Following conventions established by the telephone industry [BEL86], the accuracy of each server is defined by a number called the stratum, with the topmost level (primary servers) assigned as one and each level downwards (secondary servers) in the hierarchy assigned as one greater than the preceding level. Dell Networking OS synchronizes with a time-serving host to get the correct time. You can set Dell Networking OS to poll specific NTP time-serving hosts for the current time. From those time-serving hosts, the system chooses one NTP host with which to synchronize and serve as a client to the NTP host. As soon as a host-client relationship is established, the networking device propagates the time information throughout its local network. Protocol Overview The NTP messages to one or more servers and processes the replies as received. The server interchanges addresses and ports, fills in or overwrites certain fields in the message, recalculates the checksum, and returns it immediately. Information included in the NTP message allows each client/server peer to determine the timekeeping characteristics of its other peers, including the expected accuracies of their clocks. Using this information, each peer is able to select the best time from possibly several other clocks, update the local clock, and estimate its accuracy. Figure 130. NTP Fields Implementation Information Dell Networking systems can only be an NTP client. System Time and Date 1009