Protocol Overview - Dell C9000 Series Networking Configuration Manual

also definitive maximum error bounds, so that the user interface can determine not only the time, but the
quality of the time as well.
In what may be the most common client/server model, a client sends an NTP message to one or more
servers and processes the replies as received. The server interchanges addresses and ports, overwrites certain
fields in the message, recalculates the checksum and returns the message immediately. Information included
in the NTP message allows the client to determine the server time regarding local 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,
System Time and Date 1103