NTP sync for Cisco routers through a VPN tunnel

[rob.wright]

I have a 3002 tunnel to a 3015. Behind the 3002 is a Cisco router with NTP setup on it. No NTP traffic appears to be traversing the tunnel, there are no filters on the tunnel prevent NTP (123) traffic.

Is there something in the 3015 that has to be set to allow NTP traffic to go through?

NTP working on all other non-tunnelled connections.

[gfullage]

Make sure the 3002 is in NEM mode, and remember that the 3002 will only tunnel the directly-connected subnet's traffic. Unless that router has an interface in the 3002 private interface's subnet, and it is using that as the source address in its NTP requests, it won't work. Can you ping from that router to the NTP server across the tunnel?