Setting up NTP on a Cisco router

[BobW333]

I'm trying to configure one of the routers on our network to sync its clock with a public NTP source.

I was told that "ALL" I had to do was to add:
ntp peer a.a.a.a
to the config and it would work.....
HA!

I've tried several NTP servers from the lists at

http://www.ntp.org

and nothing has worked.

Is there a specific type of NTP server that I need or am I missing something?

 

[tschouten]

Are you behind a firewall? If so make sure these ports are open.

ntp 123 tcp
ntp 123 udp

Also, make sure you don't have an access list blocking these ports as well. Most importantly, NTP PEER is incorrect that is for updating between multiple routers (i.e. to see ones peers) that are gathering from specific servers. NTP SERVER <xyz.com> is the appropriate command. For more complete information and design schema try this for a look see.

http://www.cisco.com/en/US/tech/tk869/tk769/technologies_white_paper09186a0080117070.shtml#ntpdeploy

 

[bebop1065]

This is what I have on my network. This allows my router to serve ntp requests from other routers on my network as well as sync to a remote server.

You need to add the 'ntp server' statement so that the router know where to sync. 'ntp peer' is used for &quot;peer&quot; machines on the local network.

ntp access-group peer 1
ntp max-associations 3
ntp peer 192.168.1.1
ntp peer 192.168.2.1
ntp server 65.211.109.11
ntp server 65.211.109.1

http://soulphoto.net

CCNA student

 

[tschouten]

bebop1065 has a correct setup for NTP. He has the main router pointing to two servers as well as allowing two peers to quire the timing and allow for timing to disseminated. He basically stated what I did in a different way without making sure you check for the ports. Only reason I say to check ports is because you never know these days who is blocking what and where they are blocking it at in the schema. So to avoid the whole ordeal of, &quot;Hey what you said didn't work either!&quot; I try to cover most of the missed or forgotten it's in place problems.

 

[BobW333]

Thanks guys I'll check this in the morning.
Any suggestions for a time server to feed a router?

 

[bebop1065]

The IP's I listed are fine for me. They are local. I'm in NJ.

http://soulphoto.net

CCNA student

 

[FANCYpete]

Sounds like a plan guys, Bob you may also want to add the following to your ntp setup:

ntp clock-period 17179938 <--- (Amount to add to the system clock for each clock hardware tick (in units of
2-32 seconds).
ntp source Loopback0 <--- (provided you have a Loopback address)
ntp update-calendar <--- (To periodically update the calendar from NTP)

I'm the Fanciest of the Fancy...INDEED

 

[lui3]

ntp peer won't work unless the server you are pointing at is configured to have you as a peer as well. use ntp server instead to get your router to sync with the time source. then use the

clock timezone EST -5
clock summertime EST recurring

commands to setup your timezone and daylight savings time
once that is completed you can turnoff the ntp server command with

no ntp server a.a.a.a

then type ntp master

which will make your router the master clock for your network. then you close off ntp outbound on your network and setup all hosts/routers to use you as a time source. that is what i did.

the last part with the master command is optional but i like it since i don't have to worry about bogus time from outside our network.