CMMmicro as an NTP Server

I know that the CMMmicro can be used as an NTP Server, but my question is: HOW does the CMMmicro get the correct time?

I’ve seen no place to input the time and date or an IP address to another NTP server in the CMMmicro (version 2.2). I was told over and over again during Canopy training that the GPS and the CMMmicro do NOT provide date and time ONLY synchronization. Can someone clarify how I can use the CMMmicro as an NTP server?

In my testing environment, I can’t get the darn thing to work. :frowning:

I am 100% certain that the CMM Micro does not answer requests on TCP port 123. The only place the GPS time and date show up is on the GPS page of the APs and backhauls.


Aaron

Pg. 12 on the CMMmicro User Guide:

"Beginning with CMMmicro software release 2.1, the CMMmicro serves as an NTP server. A coordinated feature first in Canopy Release 4.2 allows the BHMs and APs to be set with the IP address of an NTP Server - the IP address of the CMMmicro. (With a CMM2, BHMs and APs directly connected to the CMM2 receive time and date information over the serial interface terminating in an RJ-11 connector.)"


HOW
does the CMMmicro get the correct time? :?

From what I understand, it gets the time from the GPS sync, however I believe it’s always the Greenwich time so you’ll always have to subtract/add whatever time zone you are in.

Has anyone here successfully been able to set up their canopy network with the correct time and date with a public NTP server IP address?

Has anyone here successfully been able to set up their canopy network with the correct time and date with a public NTP server IP address?

Yup I have. Although the time servers I use are Greenwich Mean Time so I end up with time being off, but I am used to it now. I would like to host my own server for my network though.


Aaron

we configure our CISCO’s to pull time from the CMM’s

works fine

Hmmm… I’m running v2.1.1 on 4 CMM Micros, and I can’t get any of them to answer requests on port 123. Am I missing something like the other guys? :?


Aaron

acherman wrote:
Hmmm..... I'm running v2.1.1 on 4 CMM Micros, and I can't get any of them to answer requests on port 123. Am I missing something like the other guys? :?


Aaron


Here's what I did to confirm:

on a Linux box:

~]# /etc/rc.d/init.d/ntpd stop
~]# ntpdate -u <<ipaddress>>


If you are running NTPd on the box you are using, stop it first; if not you can skip the first command.

And it worked like a charm.

Be sure to start NTPd back up when you are done:

~]# /etc/rc.d/init.d/ntpd start


My best guess would be to check network connectivity. Are there any firewalls, NAT, and the like between you and the CMM?
My best guess would be to check network connectivity. Are there any firewalls, NAT, and the like between you and the CMM?

All of my network connectivity is fine - routing is in place and everything works properly. Even on the same subnet and VLAN I don't get any NTP response (port 123).
And unfortunatly I do not have any Linux boxes to test with.


Aaron

Does anyone know if Mikrotik does NTP?

yes both as a server or as a client

GPS works on basis of transmitting the current time from multiple orbiting satellites. A position on ground will receive those signals slightly off-time from each other, and now you can calculate your position based on orbits and time skew. A side effect is you also know the current time, which you can then +/- your time zone to have local time. Nifty eh?

My CMM with the newer firmware does have an NTP, and it does answer requests. However my NTPd do not like to use it as a time source for some reason. I’ve recently read elsewhere that the CMM’s NTP rounds time to the nearest second, and so the network perceives a high jitter from the NTP’s responses. Found a post to the ISC mailing list via Google:

http://www.webservertalk.com/message1685758.html

jbaland wrote:
However my NTPd do not like to use it as a time source for some reason. I've recently read elsewhere that the CMM's NTP rounds time to the nearest second, and so the network perceives a high jitter from the NTP's responses.


I am experiencing the same thing. I've not gone so far as to fire up tcpdump to confirm, but my symptoms are the same:

NTPd quickly disregards the CMMs as valid time sources and syncs to the stratum 2 servers I also have in the config.

I find this quite unfortuinate. I would love to use the CMMs and the time source for my entire network. If Moto's implementation does inface round time to the nearest second though, then that just plain won't work.

Had a brainstorm… CMM-micro uses a linux kernel, which allows them to provide the GUI and NTP functions easily (see the copyright page on the GUI).

Perhaps due to the embedded design, it doesn’t have access to a proper real-time-clock in hardware (on the CPU), and so the NTPD suffers. All the GPS-to-PPS for the Canopy is done by “dumb” circuitry, and the CPU is just there to initialize things and give you the management interface.