Quick Notes - NTP Update-Calendar

There are some platforms that have a hardware clock that is powered by a battery. This is in addition to the software based clock. The software clock is synchronized to an external time source via NTP. At times the hardware clock may drift if it is not periodically updated by the software clock. It is best practice to update the hardware clock periodically with the software clock.

"ntp update-calendar" updates the hardware clock

Troubleshooting 5

NTP needs to be authenticated between R5 and R6. All clocks need to be synchronized. Good Luck and by the way time is ticking.

R5
__
hostname R5
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
!
!
ip cef
!
interface FastEthernet0/0
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial1/0
 ip address 192.168.56.5 255.255.255.0
 serial restart-delay 0
 no fair-queue
!
interface Serial1/1
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial1/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial1/3
 no ip address
 shutdown
 serial restart-delay 0
!
!
router ospf 1
 router-id 5.5.5.5
 log-adjacency-changes
 network 192.168.56.5 0.0.0.0 area 0
!
ip http server
no ip http secure-server
ip forward-protocol nd
!
control-plane
!
mgcp behavior g729-variants static-pt
!
line con 0
 exec-timeout 0 0
line aux 0
line vty 0 4
 login
!
ntp authentication-key 1 md5 060506324F41 7
ntp authenticate
ntp master 3
!
end





R6
__
hostname R6
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 5
!
ip cef
!
class-map match-all CMAP
 match access-group name NTPAllowed
!
!
policy-map PMAP
 class CMAP
   drop
!
interface Serial1/0
 ip address 192.168.56.6 255.255.255.0
 serial restart-delay 0
 no fair-queue
!
interface Serial1/2
 ip address 192.168.67.6 255.255.255.0
 serial restart-delay 0
!
router ospf 1
 router-id 6.6.6.6
 log-adjacency-changes
 network 192.168.56.6 0.0.0.0 area 0
 network 192.168.67.6 0.0.0.0 area 0
!
ip http server
no ip http secure-server
ip forward-protocol nd
!
ip access-list extended NTPAllowed
 permit udp any any eq ntp
 deny   ip any any
!
control-plane
 service-policy input PMAP
!

line con 0
 exec-timeout 0 0
line aux 0
line vty 0 4
 login
!
ntp authentication-key 1 md5 060506324E41 7
ntp authenticate
ntp trusted-key 1
ntp clock-period 17179839
ntp source Serial1/0
ntp server 192.168.56.5
!
end

R7
__

hostname R7
!
boot-start-marker
boot-end-marker
!
no aaa new-model
memory-size iomem 5
!
ip cef
!
interface Serial1/0
 ip address 192.168.67.7 255.255.255.0
 ip access-group 100 in
 serial restart-delay 0
 no fair-queue
!
interface Serial1/1
 no ip address
 shutdown
 serial restart-delay 0
!
router ospf 1
 router-id 7.7.7.7
 log-adjacency-changes
 network 192.168.67.7 0.0.0.0 area 0
!
ip http server
no ip http secure-server
ip forward-protocol nd
!
access-list 100 deny   udp any any eq ntp
access-list 100 permit ip any any
!
control-plane
!
mgcp behavior g729-variants static-pt
!
line con 0
 exec-timeout 0 0
line aux 0
line vty 0 4
 login
!
ntp clock-period 17179811
ntp peer 192.168.67.6
!
end