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DDNS update not working unless interface is restarted (ISR - IOS15.9)

dfhgghf
Beginner
Beginner

Hi All,

I am trying to configure an event that moves the DDNS update source between two interfaces via an IP SLA. I am trying to configure this as there are instances where the primary and backup interfaces are both online and with the command on both interfaces the DDNS update then appears to randomly update the DDNS record with either IP... So when it runs it will sometimes update the DDNS record with the IP for the backup adapter, which is not the current default route, so incoming traffic fails

The issue is that if I remove and then add the 'ip ddns update' command to an interface the update will not run until I reset the interface... The only time DDNS updates resume is when I subsequently shut/no shut the interface or reload the ISR

eg:

 

 

 

event manager applet ISP_PRIMARY_DOWN
 event track 10 state down
 action 01.0 cli command "enable"
 action 02.0 cli command "conf t"
 action 03.0 cli command "interface Cellular0"
 action 04.0 cli command "ip ddns update ddnsupdate"
 action 05.0 cli command "interface GigabitEthernet0"
 action 06.0 cli command "no ip ddns update ddnsupdate"
 action 07.0 cli command "end"
 action 08.0 cli command "wr mem"
event manager applet ISP_PRIMARY_UP
 event track 10 state up
 action 01.0 cli command "enable"
 action 02.0 cli command "conf t"
 action 03.0 cli command "interface GigabitEthernet0"
 action 04.0 cli command "ip ddns update ddnsupdate"
 action 05.0 cli command "interface Cellular0"
 action 06.0 cli command "no ip ddns update ddnsupdate"
 action 07.0 cli command "end"
 action 08.0 cli command "wr mem"

 

 

 

The problem with shutting the interface is it creates a loop with the SLA, so it just keeps bouncing the interfaces back and forth..

Is there a way to refresh an interfaces configuration without issuing the shutdown command?

It seems like a bug as other interface commands work instantly after being configured, but 'ip ddns' commands don't seem to take effect until an interface is restarted.

I'm also open to ideas about other ways to achieve this. I basically want the DDNS record to only update for the interface that is the default route, and don't even run on the other one

Cheers, Nick.

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