NTP Questions

[Rick Tweedy]

Hi all,
I have gone through the FAQ's and as much info here as I could find and after doing a design doc I am left with a couple of questions I thought you guys may be able to help with:

1. With a broadcastclient = yes if the machine has multiple NICS how do you define which subnet to listen on or will it use all?

2. If using LCL set to 127.127.1.1 the last number represent the stratus level of the clock. If I intend to eventually connect to a real strat1 machine should I set this number to 2 or 3? How does this strat level affect the configuration other than in design or concept?

3. Can I setup a peer definition on a broadcast client? If so when will the system use the peer as a polling thing? I hope only if the broadcast fails?

4. Can two servers setup as LCL strat 1 cfgs be configured as each others peer?

Thanks!!!!!

[Stefan Farrelly]

I will give this a shot....

1. I think it will listen to requests on all NIC's.I think you can use the restrict option (see /etc/ntp.conf) to allows/disallow certain servers/subnets though. If not you can always block ntp broadcasts from certain servers/subnets using /var/adm/inetd.sec

2. Are you sure the last number indicates the stratum level ? There are lots of stratum1 servers out there with numbers other than 1 as their last field. See the /etc/ntp.conf file for a list of other stratum1 servers on the internet.

3. Theres not much point having clients as peers unless those peers are also broadcasting time. Our ntp servers are setup to be peers (to each other) and broadcast only, so they stay in sync with each other and broadcast to all our other servers.

4. I would say yes. Dont see why 2 strat1 servers cant be peers of each other also.

[Rick Tweedy]

Hi Stefan

Thanks for the reply!

In the XNTP man page under primary clock support there is a section describing the use of a psuedo clock or local clock for syncing. here is says to define the server as 127.127.1.u where u is the strat level of the clock. I guess this is if you wanted multiple clock sources. My concern is that I eventually want the source to be an external clock which change the strat level. I am getting the idea this is mainly for design purposes and not really relevent in reality??

for question 3: I have two servers which will be recieving ntp broadcasts on two different subnets. One of the servers is on both subnets. By making them peers I figured if either of the source servers died then the redundancy would be there. I dont want it however polling the other as a peer if there is no problem with the broadcast. Not sure if I am explaining right or not.

Question 4: the only thing I thought wierd is that if a server is configured for LCL source for ntp server then when would the peer server be used? If the clock dies? Or again is this conceptual so that if i change the LCL source to an external time server they will continue to back each other up as peers?