From: kang lee (kanghlee@gmail.com)
Date: Fri Nov 02 2007 - 17:45:51 ART
Chris,
This is from cisco site command reference.
"ntp disable
To prevent an interface from receiving Network Time Protocol (NTP) packets,
use the *ntp disable* interface configuration command. To enable receipt of
NTP packets on an interface, use the *no* form of this command.
*ntp disable
no ntp disable* "
This command just prevents to receiving NTP packets on that interface.
On 11/1/07, Chris Riling <criling@gmail.com> wrote:
>
> I'm sorry, I should have clarified. You are correct, It's a L3 "routed"
> port
> - customer facing. I have the switch configured to sync time via NTP, so
> it
> is running globally. My question was this: if I put "NTP disable" on the
> L3
> port, does it just disable the global NTP services from ever using the
> port,
> or does it block all NTP traffic flowing *through* the port? I'm inclined
> to
> say the logical answer is only number one. Which leads me to my *next*
> question. If you only have the switch configured to use an NTP server, and
> not to act as a master, why would it listen for NTP on every port? (Other
> than the obvious "it's a global command" respone...) One would think it
> should only ever do any sort of NTP activity on the interface that's
> facing
> the server that's configured (unless of course you configure the switch to
> provide the time itself to other NTP peers)...
>
> Thanks!
> Chris
>
>
> On 11/1/07, Usankin, Andrew <Andrew.Usankin@twtelecom.com> wrote:
> >
> >
> > NTP is an IP suite protocol. So you should not be able to put this
> > command on switching port in the switch, in fact switch won't let you.
> > But if you program "no switch" on the port, it will be L3 port and if it
> > has IP it will listen for UDP:123 port (if NTP is globally enabled). So
> > here comes handy command to disable NTP on this port.
> >
> > Andrew
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > Chris Riling
> > Sent: Thursday, November 01, 2007 7:42 AM
> > To: groupstudy
> > Subject: "NTP disable" interface configuration command
> >
> > Anyone know exactly how "ntp disable" works under itnerface config mode?
> > According to the DocCD: " Disabling NTP Services on a Specific Interface
> >
> > NTP services are disabled on all interfaces by default.
> > NTP is enabled globally when any NTP commands are entered. you can
> > selectively prevent NTP packets from being received through a specific
> > interface by using the following command in interface configuration mode
> > to turn off NTP on a given interface"
> >
> > If I do that on a switch for example, does it block ALL NTP traffic on
> > that interface? Or just the traffic of anything coming in on that port
> > trying to sync with the switch itself?
> >
> > Thanks,
> > Chris
> >
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