[ntp:questions] Routers and NTP Timing loops

Jacobs, Kevin J. kjacobs at mitre.org
Wed Jun 16 02:31:00 UTC 2010

I  had an interesting experience with a Cisco router as "ntp master 9" using itself as an NTP source and it's neighboring switch as the only other  NTP source.
The switch had the exact same configuration right back at the router!. So what happens? Is NTP smart enough to know that this is a bad idea? If not, what goofy things happen if you establish an NTP timing loop? I know that if this were frequency references and stratum 3 clocks,  they would ultimately peg at the end of their frequency range (not good) but I don't know what happens from a time perspective. I had some interesting date-time issues and this is a potential root cause. Just looking to see if anyone has had similar experience and have done some in-depth research in this area.

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