Network Time Protocol (NTP) is a service that can be used to synchronize\u00a0time on network connected devices. \u00a0 Before we dive into what NTP is, we need to understand why we need accurate time.<\/p>\n
The obvious thing is network devices need an accurate clock. \u00a0Things like log files with the proper time stamp are important in troubleshooting. \u00a0Accurate timing also helps with security\u00a0prevention measures. \u00a0Some attacks use vulnerabilities in time stamps to add in bad payloads or manipulate data. Some companies require accurate time stamps on files and transactions as well for compliance purposes.<\/p>\n
So what are these Stratum levels I hear about?<\/strong> Why are there levels?<\/strong> My Mikrotik has an NTP server built in? Is that good enough?<\/strong> Do you run a VOIP switch or need to be compliant when it comes to transactions on servers or need to be compliant with various things like Sox compliance you may need a more accurate time source.<\/p>\n What can I do for more accurate time?<\/strong> If you google NTP Appliance you will get a bunch of results. \u00a0If you want to setp\u00a0up from what you are doing currently you can look into these links:<\/p>\n http:\/\/www.satsignal.eu\/ntp\/Raspberry-Pi-NTP.html<\/a><\/p>\n How to Build a Stratum 1 NTP Server Using A Raspberry Pi<\/a><\/p><\/blockquote>\n
\nNTP has several levels divided into stratum. All this is the\u00a0distance from the reference clock\u00a0source. \u00a0A clock which relays UTC (Coordinated Universal Time) that has little to no delay (we are talking nanoseconds) are Stratum-0 servers. These are not used on the network. These are usually atomic and GPS clocks. \u00a0A Stratum-0 server is connected to time servers or stratum-1 via GPS or a national time and frequency transmission. \u00a0A Stratum 1 device is a very accurate device and is not connected to a Stratum-0 clock over a network. \u00a0A Stratum-2 clock receives NTP packets from a\u00a0Stratum-1 server, a Stratum-3 receives packets from a Stratum-2 server, and so on. \u00a0It’s all relative of where the NTP is in relationship to Stratum-1 servers.<\/p>\n
\nThe further you get away from Stratum-0 the more delay there is. \u00a0Things like jitter and network delays affect accuracy. \u00a0Most of us network engineers are concerned with milliseconds (ms) of latency. \u00a0Time servers are concerned with nanoseconds (ns). Even a server directly connected to a Stratum-0 reference will add 8-10 nanoseconds to UTC time.<\/p>\n
\nThis depends on what level of accuracy you want. Do you just need to make sure all of your routers have the same time? then synchronizing with an upstream time server is probably good enough. Having 5000 devices with the same time, AND not having to manually set them or keep them in sync manually is a huge deal.<\/p>\n
\nUsually, a dedicated appliance is what many networks\u00a0use. \u00a0These are purpose built hardware that receives a signal from GPS. the more accurate you need the time, the more expensive it will become. \u00a0Devices that need to be accurate to the nanosecond are usually more expensive than ones accurate to a microsecond.<\/p>\n