Warning message

  • Cisco Support Forums is in Read Only mode while the site is being migrated.
  • Cisco Support Forums is in Read Only mode while the site is being migrated.

Problem with NTPv4 over IPv6

Unanswered Question
Jun 29th, 2012
User Badges:

Dear All,

When I was doing PoC for IPv6 transition, I had to work with NTPv4 for native IPv6. I am using 3825 running 12.4(24)T  adv enterprise.

As per Cisco documents NTPv4 is supported in 2 modes.

1. Client - Server.

2. Multicast.

I am presently interested in Client Server Mode

In this mode I configured Server with command. 'ntp master 2'

And on the client I configured:


ntp update-calendar

ntp server FD00:0:0:60::1 source Loopback0


Loopbacks of both server and client are reachable using OSPF.

But NTP remains unsynchronised forever.

Are there any known issues with NTPv4 over native IPv6 ?

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
fabios Fri, 08/24/2012 - 13:52
User Badges:

Hello Maulik,

I am running a 1921 in a production environment and the NTP config includes:

ntp update-calendar

ntp peer

ntp peer

ntp peer

ntp server

ntp server 2001:67C:288::128

(the router is running dual stack)

sh ntp associations


  address         ref clock       st   when   poll reach  delay  offset   disp

+~    2    710   1024   377  2.047   0.721 15.742

~   .STEP.          16      -   1024     0  0.000   0.000 15937.

~    4    862   1024   377  2.006  -1.532 19.759

~  .STEP.          16      -   1024     0  0.000   0.000 15937.


           2    703   1024   377 97.275   5.325 14.800

* sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured

So apparently NTP works over native IPv6. I suppose connectivity (including access lists) is verified between the two devices .... try debug ntp packet and events.



maulik.parekh Fri, 08/24/2012 - 22:36
User Badges:

HI fabios,

Thanks for your reply.

I was able to synchronize NTP when running dual stack. It was just that when i used native IPv6, it didn't work.

Not a single ACL configured.

Strange thing is that when i use IPv6 on server, (i.e. Master) it gets reference clock as some public IPv4 address and says synchronised, whereas I never configured that.

Unfortunaltely we have dismanteled tht setup. If i get a chance again, I will surely post the configs.




This Discussion

Related Content