NTP Server on a Cisco Router

Mar 19, 2008 7 Replies
NTP Server on a Cisco Router open original image

HI All,



Which is the smallest Cisco router that can be configured as an NTP Server? Can i configure an 1800 or worse an 871 as an NTP server.



Regards,



Kiran


I am sure that an 871 or 1800 will be able to be an NTP server

I have just checked and a 877 *with* Advanced IP Services Feature Set can be an NTP Server. I have an active association with it now.

I have the idea that the basic 870 Feature Set can not be an NTP client - SNTP only. No idea about server but my guess is not.

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you need to register and maybe need a commercial relationship with Cisco too.

In general all features work across all platforms

83x upwards.

Of course - an 870 has no battery backed clock of its own and I would expect it to be a pretty terrible time reference. Perhaps drifting by hours a year.

No idea about an 1800 - Iwould guess no clock there either but I am not at all sure.

But you could sync it to an external source - there seem to be plenty of public ntp sources out there.

Sam

Have been using the NTP Server on an 806 for years.

Currently using c806-k9o3sy6-mz.123-8.T11.bin, but the server function existed in much earlier releases of the IOS as well.

It's sync'd with an external time source (Internet), and is used to sync the hosts on the internal network.

No issues.

Best regards, News Reader

Of course you can sync the router to an external source, but if you are running time based services (as acl's) you can have unpredictable behaviours without a hardware calendar after a reboot. Bye, Tosh.

Not really, just include a time-based ACL that allows only NTP through if the date is before some time well in the past. Last time I checked, routers without a clock were very consistent about setting the time to their concept of "the dawn of creation" whenever rebooting. Once NTP sets the time correctly (and to the present era) your ACLs will have the correct time and work correctly.

Good luck and have fun!

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