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Cisco Mobility Express - Controller AP sending out 0.0.0.0 as IP address

jerrysafetynet
Level 1
Level 1

The AP that’s designated as the controller keeps going offline in our monitoring system because the IP address of the AP keeps reverting to 0.0.0.0 in the Nomadix (Nomadix is our Gateway/Firewall onsite).

The AP has 2 interfaces, the mobility express interface (which will transfer to another AP in the event that this one goes down) and the actual AP interface.  Both are configured with static IP addresses, but for some reason the IP for the AP interface keeps reverting to 0.0.0.0 in the Nomadix.

 

The AP itself never loses its IP.  When onsite and consoled into a switch on the same network/VLAN, I can maintain a constant ping to the AP interface and the ME controller is showing the AP as online.  It's just at some points during the day the AP interface sending a broadcast message with a 0.0.0.0 IP address and our gateway (Nomadix) is seeing this packet and registering it's MAC address as 0.0.0.0 (we run a layer 2 network).  We monitor the APs on the ME deployment from our Nomadix Gateway and when we see this 0.0.0.0 our monitoring system says the AP is down. 

 

ME Firmware is 8.5.120.  I do have a packet capture but I'm unable to upload it here.  In it you can see the 0.0.0.0 and broadcast address of 224.0.0.18, these are all coming from the AP interface MAC address of the controller AP.  Any help would be greatly appreciated.

 

Thank you

2 Replies 2

jerrysafetynet
Level 1
Level 1

Here is a screen shot of the packet capture.

patoberli
VIP Alumni
VIP Alumni
That's a multicast packet. As this is layer 2, an IP address is not needed (in some cases) in the header. I think this is what you're seeing here.
Some information for what VRRP (that's the multicast protocol which is running): https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-2/b_Mobility_Express_Deployment_guide/b_Mobility_Express_Deployment_guide_chapter_01011.html
My suggestion, filter the multicast packets on the firewall/monitoring, or ignore them if possible.
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