From: R. Benjamin Kessler (ben@xxxxxxxxxxxxxxxxxxxxx)
Date: Wed Nov 07 2001 - 12:01:08 GMT-3
Here's a CCO link that talks about the NTP association and the polling
interval.
http://www.cisco.com/warp/public/620/ntpassoc.html
It appears that this is an auto-magic setting. I can't find a way to
manually manipulate the polling interval. I do know that when I initiate a
new router with NTP it will start at a 64-second interval; according to the
CCO doc it will gradually increase over time (given some pattern of
successful synchronizations). I have a bunch of routers that have their
polling interval running at the maximum of 1024.
Regarding the broadcast and broadcast client configuration parameters.
These are interface-specific parameters. The broadcast command tell the
router to broadcast ntp messages to other clients on the segment; adding the
"client" parameter tells the router to listen for broadcasts from an NTP
server on the segment. If you configure the router as a broadcast client
you'll see the IP address of the NTP server show up in the "sh ntp assoc"
display.
I have done this a couple of different ways in the past. At one client, I
set a backbone router to be the NTP master server and then synchronized from
there on out to the edge of the network. This works pretty well but you
have to manually ensure that the time on the master is accurate - the clock
on 7513's do tend to drift over time.
At another client, accurate time was a bit more critical and we had a pair
of GPS receivers that would get time from the satellites and act as stratum
1 NTP servers. All of the routers ( <50) were configured to get their time
directly from the NTP servers. To take it a step further, the workstations
were configured with NTP clients that would listen for multicast time
advertisements. The routers connecting to the end-user segments were
configured to source the multicast packets for the appropriate subnets.
Hope this helps.
Ben
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Kevin
Sent: Wednesday, November 07, 2001 1:00 AM
To: ccielab@groupstudy.com
Subject: Does ntp broadcast is needed for Lan&Wan interface ?
Hello all, I setup ntp master and server.
I found ntp can work properly, but the clock to be sync too late.
How can I speed up time sync ?
The second question is the clock can be sync even if I can't setup
ntp broadcast and ntp client broadcast command on LAN interface. What
funtion do these
two command do ? I don't still test it on WAN interface.
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