![]() Time servers on the same stratum level can be configured to act as a peer with other time servers on the same stratum level for backup or verification of time. Stratum 16, the lowest stratum level, indicates that a device is unsynchronized. The larger the stratum number, the lower the stratum level. Smaller stratum numbers indicate that the server is closer to the authorized time source than larger stratum numbers. They could also act as servers for stratum 3 devices. Stratum 2 devices, such as NTP clients, synchronize their time by using the NTP packets from stratum 1 servers. The stratum 2 servers are connected to stratum 1 devices through network connections. They function as the primary network time standard to stratum 2 devices using NTP. The stratum 1 devices are network devices that are directly connected to the authoritative time sources. In the figure, they are represented by the clock icon. Specifically, stratum 0 devices are non-network high-precision timekeeping devices assumed to be accurate and with little or no delay associated with them. Stratum 0 devices such as atomic and GPS clocks are the most accurate authoritative time sources. NTP Operation CCNAĪn NTP network gets the time from authoritative time sources. Stratum 1 is connected to Stratum 0 clocks. NTP servers are arranged in three levels showing the three strata. The figure displays a sample NTP network. The synchronized time is distributed across the network by using NTP. The stratum level is defined as the number of hop counts from the authoritative source. Each level in this hierarchical system is called a stratum. NTP networks use a hierarchical system of time sources. NTP uses UDP port 123 and is documented in RFC 1305. When NTP is implemented in the network, it can be set up to synchronize to a private master clock, or it can synchronize to a publicly available NTP server on the internet. ![]() ![]() A group of NTP clients that obtain time and date information from a single source have more consistent time settings. ![]() This protocol allows routers on the network to synchronize their time settings with an NTP server. If a router reboots, how will it get an accurate date and timestamp?Ī better solution is to configure the NTP on the network. Even in a smaller network environment, the manual method is not ideal. Updated from 21:32:31 UTC Fri to 20:36:00 UTC Fri Nov 15Ģ019, configured from console by console.Īs a network grows, it becomes difficult to ensure that all infrastructure devices are operating with synchronized time. Typically, the date and time settings on a router or switch can be set by using one of two methods You can manually configure the date and time, as shown in the example, or configure the Network Time Protocol (NTP). When the time is not synchronized between devices, it will be impossible to determine the order of the events and the cause of an event. It is important to synchronize the time across all devices on the network because all aspects of managing, securing, troubleshooting, and planning networks require accurate timestamping. It is the primary source of time for the system. The software clock on a router or switch starts when the system boots. Packet Tracer – Configure and Verify NTPīefore you get really deep into network management, the one thing that will help keep you on track is ensuring that all of your components are set to the same time and date. ![]()
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