MX - DHCP leases exhausted

[RaphaelL]

Hi ,

I'm always receiving DHCP leases exhausted alerts but when I take a deep look , the DHCP pool is far from exhausted.

10h52 MX came online ( was down for 24h )

10h54 alarm received

10h56 Validations were made on the MX ( see results below ) 

I don't get it... 

We are running 14.39

Thanks ! 

[NolanHerring]

I think your looking at the wrong DHCP Pool

Look at the one below the red boxes, the /20 is nearing its limit.

It's almost maxed out. I don't think it only emails when 100% are used. Its probably like 95% or something.

[RaphaelL]

Hi Nolan , 

This was the alert  :

The security appliance in the network XXXXXXX was unable to issue an IP address to new clients on subnet 192.168.1.0/24'192.168.1.1 because it has exhausted its pool of DHCP leases. New clients will not be able to connect to the network until this issue is resolved (e.g. by increasing the size of the subnet).

It is indeed the DHCP pool that is almost empty

[NolanHerring]

Ok that is strange

Can you provide a screenshot of the DHCP settings please

[RaphaelL]

Sure ! 

There it is : 

[NolanHerring]

Yeah I don't know now lol

Have you contacted support. It sounds like a bug because I don't see anything config wise that looks wrong. Maybe someone else will notice something I don't =(

[RaphaelL]

Yeah when I get back from vacation I will do that. 

I'm always asking here first 🙂 

Thanks for helping me !

[General-Zod]

I have seen this before on a MX using its dhcp mechanism. There was a rouge ip phone that kept changing the last part of its MAC address and it kept consuming IP’s until the pool was exhausted. The dashboard however showed plenty of available addresses. After a call to Meraki support they were able to dig deeper and they could see that the pool was indeed exhausted. It is my understanding that the dashboard only shows successfully accepted dhcp offers. The rogue IP phone in question just kept flipping the last part of its mac and exhausted the pool. Sadly whenever the event occurred I wasn’t available to perform a capture.

Hope this helps.

cheers