MX64 cannot renew IP on WAN

[KimSkifter]

Our customer has a DHCP assigned fixed IP internet subscription.

We have assisted him in narrowing his packet loss every two hours down to the MX64 fails to get its IP renewed.

The poor MX64 is trying to renew its IP during the leasetime, but gets no offer back.

Not until it gives up, releases its IP, and do a DHCP discover (broadcast).

Then it gets its fixed IP straight away.

The ISP properly runs a setup with some Junipers invoilved.

The MX64 runs F/W 18.105 (Problem was detected running 17.10.2)

Is there a bug in Merakis implementation of the DHCP protocol? I.e. missing options etc.?

Or is it related to the ISPs configurations? (I know what MErsaki support will answer on this...)

[DarrenOC]

Morning @KimSkifter, little bit confused reading that one.  Are you saying the WAN interface has an IP assigned by the ISP by DHCP but it’s a fixed IP. If it’s fixed I.E static what happens if you simply statically assign that IP to the WAN interface of the MX?  2hrs also seems like a very short lease time.  Do you get the same issue if you connect a laptop to the ISPs router?

[KimSkifter]

Sorry, may be my Danish/English 🙂
The MX64 gets a DHCP assigned IP, not static configured IP. But the ISP aalocates the same (fixed) IP based on MAC address.

2 hours lease time is short, but the chpoice of the ISP.

We have not had the chance tp connect other equipment, to test for same problem. 
But I do acknowledge that different manufactors use different implementations of the DHCP protocol.
That's why I am looking into any known bugs with Meraki on this topic.

[DarrenOC]

Hi @KimSkifter , so if the ISP are assigning the same Fixed IP all the time why not just statically assign that IP to the MX?  If it works you’ll have a stable connection and a happy customer.  

[KimSkifter]

Static IP configuration is not an option due to choice of ISP (and no, another ISP is not an option either...)

I am looking for some technical insight in Merakis implementation of the DHCP protocol

[ww]

I dont think there is documentation about this. but you have the capture so you should be able to verify if all required info is send to the dhcp server.

To me, it looks more like a dhcp server problem. you can see the renewal/request from the client. but there is no response from the dhcp server. no ack or nak.  Does the dhcp server even get that packet?

"the DHCP server returns either a DHCP-ACK unicast confirming that the client's lease has been extended, or a DHCP-NAK unicast denying the request."