MX100 Receiving IP conflict alerts despite there not being an IP conflict.

[Tony69]

Good morning,

I am receiving tons of IP conflict alerts for a backup repository I recently set up. I bonded the NICs and re-applied the IP, hence the IP conflict. How can I resolve this issue? 

Thanks.

[RWelch]

There is no mention of what Meraki equipment you are using however there are a few tips below if it helps.

The MS's LACP hashing algorithm uses traffic's source/destination IP, MAC, and port to determine which bonded link to utilize.

NOTE: When configuring LACP port-channels on uplinks between remote switches/stacks, always configure the remote/downstream side of the port-channel first. Once the config has been applied configure the LACP port-channel on the upstream switch. This insures you don't strand the downstream switch. 

Link Aggregation and Load Balancing 

You can try to acknowledge the dashboard IP conflict alert and give it time to clear itself up.  If it persists, you might consider taking a look to verify the backup device NIC settings are configured for link aggregation.

Another option to consider would be to Release and renew IP addresses.
To resolve the conflict, you can release and renew the IP addresses of the conflicting devices. Go to the network settings on each device and release the IP address. Then, renew the IP address to get a new one.

The MX (itself) does not run LACP or any link aggregation protocols. Connecting aggregated ports to the LAN of the MX is not supported; all connected ports should be un-aggregated.

MX Layer 2 Functionality 

[GIdenJoe]

You should investigate if multiple mac addresses are using the same IP address.  I have never found dashboard to be wrong about this.

If they see that a different mac address is using an IP address that has just been used by another mac it will throw that alert.  Maybe write the mac addresses involved down and perhaps do some pcaps to see if your device is not changing it's mac address.  You can easy apply filters on your capture to just limit between those mac addresses.

[BlakeRichardson]

I get a IP conflict every two or so weeks on my home network and when I look into it one of the MAC's that is conflicted the dashboard has no history on it. 

[PhilipDAth]

Are you using Windows NIC Teaming in Switch Independent mode?

If so, it sends from the same IP address using both NICs.

If you have a Meraki Switch, configure and change to LACP mode (it needs to be done on the server and the switch).

https://www.techtarget.com/searchnetworking/tip/Configure-NIC-teaming-in-Windows-Server

https://documentation.meraki.com/MS/Port_and_VLAN_Configuration/Switch_Ports#Link_Aggregation

[Tony69]

Hello,

I am using a MX100 firewall. I changed the subject line to reflect this. Sorry about that.

Thanks

[RWelch]

Do you have a switch connected to the MX100?

If not, the MX (itself) will not accommodate LACP or any link aggregation protocols. Connecting aggregated ports to the LAN of the MX is not supported; all connected ports should be un-aggregated.

[PhilipDAth]

Changing the NIC team to use active/standby (primary/backup) should resolve the issue.

[PhilipDAth]

Actually, depending on the backup platform, another solution would be to break the NIC team, and then just give each NIC its own IP address.